*@Uncle Tony* I know you know this, but you forgot to mention WHY there's a low pressure bypass in oil filters. For those who don't know though: that bypass system actually NEEDS to be there because above a certain PSI, the oil can't flow through the microscopic holes in the filter media fast enough, so they put a pre-determined PSI bypass in there to keep the oil pump's pressure from blowing out the filter media. It's not an ideal filter design, but without making the oil filter much, much larger to accommodate 40-60+ PSI of oil filtering capability, they put in an oil pressure bypass instead. Sadly, it's just a necessary byproduct of such a small screw-on filter design.
Youre missing one important factor, flow rate of specific viscoty oil through filter media at what it is rated for in microns. Say a 30wt at 10cst "centistokes" rated at 200 degrees. Oil thins out as the engine warms so the bypass can function during a severe cold start when the oil is essentially a soft mushy brick in your oil pan if its conventional oil.
@@rickpatterson7438 ive looked over so many brands and viscosities of oil and even some of the most top notch oils have a maximum permitted API viscosity of 6,600 at -30 degrees. They hit about 12 at 200 degrees. To go from 5k to just 10 thats how much oil thins out during warmup. Every day. Every trip. And that was an API rating for amsoil OE api certification.
The bypass works on differential pressure across the media and not just a static value. At 40 pounds pressure you may only exhibit 10 psi differential across that media, thus with a 20 psi setting for the bypass spring, the bypass remains closed. The bypass is open a lot on more or less any filter but its not based on the static pressure you read on your oil pressure gauge.
So if you don't mind can you answer a question or two. I own a 65 Mustang with a 302 that at cold start is at 82 psi. Once warm its around 40. It will drop below 30 at idle when good and warm. Am I filtering any oil at all? I know K&N sells two different filters. One I believe they advertise as ia high-flow, the other as a high filtration. I went with the high-flow because I didn't want to increase oil pressure. Any information you could give me would be appreciated thank you.
The differential also drops drastically as the engine warms up. Oil flow through the media increases as it thins out. At 200 degrees when the average 30wt oil is at its rated viscosity around like 10Cst. It goes through that media like water. And higher rpm shouldnt affect the filter flow unless the unload valve in the pump fails then it will likely blow the filter clean apart 😅.
I'll stick with my VW oem filters and not mind the cost , because the bypass is something nuts like close to 35-40psi. Or any of their own supplier like mahle Bosch or mann.
@@MrTheHillfolk theres a good reason too. VW rated and licensed oils such as vw502 and vw505 can go as high up as 50wt oils om the hot side. Vw understood this and added such bypass requirements
@@BPattB i may be able to help you, oil weight is a factor here the reduction of pressure is the increase of flow. So when cold the pressure behind your bearings is 80psi when oil heats up it becomes more and more fluid and flows much greater volume. Thus at idle you could see only 30psi but at the same time the oil is flowing much faster to its destination and in greater volume depending on oil pump. Now 80psi is the limit inside your oil pump relief. The spring is limited at around that psi or is now overcoming that spring all together when cold. Take that measurement hot at operating temp of your thermostat, at roughly above idle preferably higher at like 1500-2krpm. That is your spring limit. At that temp your oil is flowing the fastest and easiest it cam and that just shows your pumps pressure limit but NOT its volume.
I'm having a hard time believing that the oil filter is functional pretty much only at idle and not during 2000rpm cruising. Because that would make the oil filter pretty pointless, and something gives me the feeling that people haven't been using oil filters for the last 100 years for no reason.
And you are correct and Tony messed up on this one. That large spring only seats the cartridge to the top of the can. Any pressure pushing down on the filter media is also pushing up from the bottom. The bypass is built into the filter media and uses a separate and smaller spring.
@Jared Lancaster Right. Oil filter takes everything from the pump. If the filter gets clogged, there’s a bypass mechanism, but that only works on differential pressure across the filter. UT stepped in it pretty hard here.
@@ChrisPBacon-ok7ir almost correct its the differential pressure between the inside and the outside of the filter media is equal the bypass is close only when the pressure drop across the filter media exceeds the bypass spring pressure will the valve open like in a clog filter condition or a cold start in 32f and lower Bypass valve is closed 99% of the time the engine is running
Normally UT is spot on, but I think the spring reacting to the pressure differential before and after the filter versus the oil pressure of the engine is significant. It would seem that this would challenge UTs theory that no filtration is happening at highway speeds
I've been mistaken before, but I was reasonably sure the bypass rating on those valves is calibrated for the _differential pressure_ across the inlet and outlet, not the overall pressure in the system. I have several vehicles that never have oil pressure below the bypass rating of the filter, which generally is something like 8-22psi depending on the application. The implication of that would be that the filter _never_ filters any oil at all. I find that difficult to believe... The motor oil on my non-filtered power equipment looks like tar after 50 hours and my filtered automotive engine oil can look like new for hundreds.
Tony is wrong on this, the pressure differential is absolutely different than the engines oil pressure he is referring to. The pressure that builds in the filter increases as the filter clogs with time and its internal pressure increases, at a point it will open the bypass valve. The main engine pressure is on the other side of the valve 😂. The top valve he shows is the oil drain back valve that prevents dry starts. He's really spreading misinformation here.
No you are rigth he wrong this would make no sense if tony was rion this one it absolutely based on differential pressure and ther not 2 bypass valve this is just absurd
You are 100% corrrect ... was a long term 'filtration engineer' That 'valve' prevents turbulence (higher resistance to oil flow inside the filter material) during momentary extreme engine rpm episodes ..... and clogged / dirty filters.
Is this the same VW air cooled engine that is well known for only lasting 50-60k miles under normal use ? And a major reason is that they have no oil filter ? Me thinks yes.
@@joncrisler6001 Has nothing to do with filtration...airflow to cylinder #3 is partially blocked by the oil cooler so it runs hotter. The airflow issue was fixed in '72 or so with an offset oil cooler and can be retrofitted to older engines
The air cooled VW oil and air filters work on physics. The sieve part stops the large chunks and the way the oil\air is forced to do a very sharp right angle turn makes the metal or dust get caught due to centrifugal force. It's how the South Africans enriched their uranium to build their bombs and fuel their two power stations.
Wow. He is totally wrong. That cartridge has a pressure balance on the top and bottom. That’s not how the bypass works. It acts on a pressure differential across the filter not what your actual oil pressure is.
@@UncleTonysGarage right but you showed the whole cartridge moving up and down which is wrong. Also your statements about it being in bypass mode is also wrong. The filter maybe has a 5-10psi drop across it so you oil pressure could be 60psi at 5000 rpm and the oil is still going thru the media. You should fix this video.
Sorry but this is completly wrong , the vavle works on pressure differential from the inlet of the filter to the outlet of the filter , so only if the pressure going in to the filter is 20 PSI higher then coming out it will bypass to ensure the engine gets oil if the filter is clogged for some reason.
And it does so via a separate bypass valve and spring in the bottom of the media cartridge. The large spring is just there to hole things together tight. Tony screwed up on this one.
Yes! usually agree with Tony but he entirely off- it’s pressure differential. A 20lb bypass could kick on at a 30>10 split but not 30>20. or open at 60>40, yet not at 60>45
I thought these things operated on pressure differentials - i.e. the difference between the pressure going in and the pressure going out. The setting of 10 to 20 PSI (actually PSID) would make a bit more sense to me.
Yeah most people don't understand between differential and static pressure. If there is 40 pounds static but only 10 pounds differential across the media, with a 15 pound spring the bypass remains closed. So this entire video is incorrect lol
Yes what Bill said is correct its just unfortunate that this disinformation will reach a lot of uneducated people in a cult format. Lubrication engineers have spent decades designing these filters and engines. Its called "full flow lubrication" for a reason set apart from the 1950s bypass systems which i do have on old flatheads. Its an honest mistake and im sure as close as tony is to big brains like David vizard someone may be able to correct him and this video taken down.
Oh great one, I find I must disagree. The bypass operates on the differential pressure between the inlet (oil pump outlet) and the outlet (the rest of the engine). (If what you are saying was true, if an oil filter had no media, there would be no oil pressure developed.) So, if a filter has a 20 psi bypass valve, there must be 20 psi of backpressure developed by the media before the bypass will open. This will only happen if the media is getting pretty plugged. This is why they are called full flow oil filters, because they filter all oil after the oil pump and before the engine. The older cars 216 - 235 Chev six, for example) were built without an oil filter. If you ordered the oil filter option, they bled off a little oil after the pump, which was filtered, then sent back to the oil pan. This reduced the oil pressure, but not by much. Only a little of the oil was thus filtered, but of course eventually it all got filtered.
The pressure is determined largely by how tight the engine's tolerance are - hence Bottle Rocket having practically none. If the filter were causing that much back pressure it would be severely limiting the oil supply to the engine.
@@DuckyHunter812 Please forgive my ignorance - I never was the brightest bulb on the tree. I didn't make my point clearly, which is a common problem with the written word. What I was trying to say was: the oil pressure generated by the engine (bearing clearances, etc) doesn't matter. If the oil filter media generates > 20 psi backpressure (due to high viscosity oil, plugged media, etc), the bypass will start to open, assuring adequate flow of oil to the engine, although obviously unfiltered, the thought being that adequate flow of even unfiltered oil is better than inadequate flow of filtered oil. (I suppose on reading this later I will find it inadequate too, but it 's the best I can do right now.)
Wouldn't that internal filter spring only act on the internal back pressure produced by the filter media itself? The overall system oil pressure would act on both sides of the oil filter. That way if the media plugs, it won't starve the motor.
The spring at the bottom is not the "bypass". That spring is there only to hold the filter cartridge tightly against the top of the filter can. The actual bypass valve is inside the filter cartridge at the bottom.
I would say it's a second bypass as a product of design. It's not that it pushes the filter media down compressing the spring, but oil could get forced between where the two surfaces meet at the top of the pressure was high enough. How much that is relative to the main bypass IDK.
15 years as a BMW Motorcycle tech/service/parts manager I have had to explain this a thousand times. Mostly to the people that spin a fram from a toyota onto a BMW motorcycle to save money because "it spins right on" not realizing that there is a 60psi difference between them. Many engines died, to bring them this information...
If the filter is full of oil that same amount of pressure is also acting on the bottom of the filter media assembly, pushing it upward in the same direction as the spring. Just a thought. Not as simple as just the incoming oil pushing down against the bypass spring.
A high velocity, the oil will push down some. There's 3 things going on here. But sometimes that big spring is a leaf instead. I like oversize filters. Probably a waste but I'm thinking about cold flow rates. My Penny's worth. I'm just a nerd.
Tempted to dent the cap and boost the spring pressure now, turn it from an outtie to an innie lol. The flap by the threads is an anti drain back. Heard it prevents it all from going to the bottom end by just gravity.
First the spring he talk about is not the bypass valve it's the center button he point at the end of the video Denting the filter will do nothing And it work on differential pressure(pressure drop)what he said make no sense
@@legros731 He put up a new one correcting things. The spring is the pressure differential bypass, it allows the media cartridge to move out of the way above 20 psi.
The oil pressure flow that comes inside the oil filter applys equally at the top surface and at the bottom surface of the filter cartridge, so the bottom spring always overcome and maintain the cartridge against the top, made with a steel wire the bottom spring is the cheapest solution used to get top cartridge sealing as it force the cartridge against the top rubber seal (also called anti-drain back seal). This avoid oil from going directly to the exit of the cartridge without filtration. The cartridge never move inside . The bypass when it exists acts when differential pressure due to media clogging allows oil flow to go through it because it is less restrictive than going through the média. When there is not bypass in the oil filter the bypass is located in the oil filter mount.
that big lower spring it's just to keep the filtering element snugly sealed against the top plate... have in mind that oil pressure once passing through the rubber anti-return membrane acts in all filter element surfaces (top + lower plates + filtering media). The only bypass is that small hole - at lower side of the filtering element.
Bingo, someone finally stated the true job of what tony mistakenly called a bypass valve. That springs job is to hold the element up. Any oil pressure pushing The element down against that spring will also be pushing up on the element with the same amount of force. That’s why there’s an actual bypass valve in the bottom of the element that will open when the media becomes restricted. I was taught when attending a very expensive seminar given by a filter manufacturer.
@@kellismith4329 the spring is a very inexpensive way to hold the element up. Not only does the same spring work for multiple different filters it requires no special installation or tooling as it is simply dropped in during assembly. It also will automatically compensate for thermal expansion and contraction. So in essence the spring is simply the best way to do the job.
My 1974 VW Bettle, which I purchase new in 1974, never used an oil filter. All it had was a screen. When I changed the valve cover gaskets at 95K the insides were spotless. Take that for what its worth.
My father said his '53 Pontiac Chieftain had a "built-in" oil filter. While I remember that car from when I was a kid, I certainly don't remember seeing any sort of oil filter. My father did start using detergent oil as soon as it came out.
First off i enjoy your videos... The function of the coil spring in the bottom is to keep the entire assembly inside pushed together... The bypass is the hole in the bottom of the end cap that is spring loaded with a predetermined pressure spec'ed for the application... Some filters don't have bypasses at all due to it being internal to the engine!! The full oil pressure of your engine is not rushing through the filter bypass, it is the static difference or the left over pressure that could not make it's way through the filtering element because of either restriction, cold start or high viscosity oil..!! Bottom line is use a nonrestrictive filter, change your oil and filter regularly, use the correct viscosity of oil and the oil filter will rarely be in bypass mode!! Love your channel btw!!
Wish you could do a talk on the old Frantz filter system. Some called it the 'toilet paper' system. One roll and one quart of oil! We also went to a dry-sump system on anything that drove to the strip, then ran, then drove home.
So I might as well use the cheapest filter and continue to change my oil every 3 thousand miles like I have been doing since I bought it new. Thanks for this. I had no idea.
so I did a ton of research on this, using a larger filter allows more oil to pass through the media without opening the bypass. for instance, my 94 supra has a tiny oil filter, the upgrade that people use is to a first gen tundra filter, the upgrade tundra owners upgrade to lexus lx470 filters lol. so my supra has a 6 inch long oil filter from a lx470, and the only upgrade from there would be a 8-10 inch wix commercial truck filter without a bypass. YOU can literally figure out the filter specifications (thread pitch, length, diameter, bypass psi) your oem filter is, cross-reference this info from frame to wix or other companies filter databases and just size up to wherever. you don't necessarily need the filter bypass if you live in a hot climate or you only drive the specific vehicle during good times of the year. also having more filter media allows more paths for the oil to flow without building up pressure and triggering the bypass valve!
Hi T, hate to step on your turf, however, with great respect, that internal bypass is in case the filter/paper/media, gets plugged. The oil will then "bypass" the filter/paper/media, and flow directly to the engine and not blowup the filter can or starve the engine for oil, thereby causing a catastrophic (really bad) loss/lack of oil. Oil is always flowing through the filter, it does not matter how much oil pressure there is. It depends on the pressure difference between both sides of the filter (inlet vs outlet) or backpressure, when the difference gets to great, the spring is pushed down. Also there is the oil pump bypass valve in the oil pump, it is not a pressure relief valve, if there is too much backpressure in the filter the valve will bypass the oil directly to the engine. Of course on newer engines they also control the oil pressure electronically, but there is always the mechanical bypass, just in case. Blue Mule PS shout out to LS, just expanding on his/her thoughts
Different part number filters are supposed to have different bypass psi ratings per oem specs. That said you would have to test each out to see. The race specific filters normally have a bypass that is much higher.
Question: Does not the oil pressure act on the bottom of the filter element (pushing up) as well as pushing down onto the top of the element? If true, then the spring would make a percentage of the oil go through the element. Assuming that the element is not clogged.
Correct. The pressure pushing down on the top of the filter canister also pushes down on the oil under the filter canister, so the pressures on the top and bottom are always equal. That's why the actual bypass valve is inside the filter canister.
They bypass but it is not a binary on-off. If the pressure is too high, some of the oil bypasses the filter. You don't need 100 percent filtering anyway.
You are mistaken. This is why. If the filter element has 50 psi on the pump side, that is pressing against the element, sure, but if there is 49 psi after the element, this is pushing back against it so the bypass only sees that 1 psi difference, not the whole 50 psi. John Cardogan was big enough to publish a retraction the other day. Let's see if you do too. ruclips.net/video/djuy1KFOTLY/видео.html
From Leo: Good report Tony. Filters are a good thing and they help. (I had an old Dodge that had a canister filter on the fender and it only filtered a little oil on return). If you keep the oil changed, a filter is not even needed. I drove over 90,000 miles on an XS 650 Yamaha that does not even have a filter, just a bronze screen in the sump to strain out the big pieces. The guy I sold it to rode it all the way to Seattle from Chicago that week and was still riding it a year later. CB series Honda's just had a centrifugal cup on the end of a shaft that trapped any metal chips behind a little lip in the spinning cup.
UTG you're a great guy with a ton of useful knowledge, but I think you are wrong on this one. The inflow oil pressure actually helps the spring (adds pressure ) keep the element tight against the end plate. The push valve at the bottom allows bypass if the filter is clogged. The pressure relief valve in the oil pump is in place to dump excessive pressure on cold startup when viscosity is high. Its' called full flow filtration for a reason.
Tony, I’ve never thought about this and it makes perfect sense. That’s why you see exploded/shredded parts in valleys and pans. Wow. As an old shade tree guy ((76) I’ve never thought of this. And of course there’s no mention on oil filter specs noting the psi rating on the by pass valves. Good one Tony.
You been fooled or tony is dumb on this one The valve work on differential pressure ie pressure drop across the filter media System pressure is irrelevant
I change my filter about halfway through my oil change. Been doing it for about 30 years. It doesnt cost much when you buy them by the case on sale. And you never have to worry about your filter being very dirty. Cheap insurance
The Broken Life is correct "... those valves is calibrated for the differential pressure across the inlet and outlet, not the overall pressure in the system." As a retired Aerospace Engineer with over 35 years of oil system designs on jet engines, reciprocating radial piston engines and helicopter gearboxes including the JSF Lift-Fan gearbox, the oil filter can be a "full flow" design which filters 100% of the oil flow (when the oil is not as thick as molasses) or a non-full flow design. All good filters should have a "by-pass" valve to by-pass the filter when the "pressure drop across the filter" exceeds the set point of the valve. This will happen when the filter media catches too much contaminates (in service too long or a catastrophic failure) or the oil flow rate and /or oil viscosity exceeds the filter medias surface area to permit adequate flow without restricting the flow. I would guess most modern cars (since the 1960") have an OEM oil filter similar to that show on the Fram website - having an "anti-drain back "valve" and filter media "by-pass" valve or a "keep oil pressure in the engine" provision. www.fram.com/products/oil-filters/titanium Then again, I'm assuming all the OEM engine designers know how critical, clean and pressurized oil is to the successful operation of their engines are. I like your videos Uncle Tony but felt I needed to put my wooden Nickle into this video. My apologies if I'm wrong. OBTW, my wife says I'm never right - does that mean I'm never wrong? LoL
I like the metal reusable filters for this reason. Oil flow is faster over a metalic mesh. Because the media is stiffer the bypass is also higher pressure. They do have a larger micron rating however. So you win some you lose some. I am not talking about the screen type, but the catrige style which fits into a typical looking screw on filter
My dad worked at one of the major filter manufacturers for over 30 years. He said the engineers told him that after about 500 miles the media is clogged to the point that its in full bypass all the time anyway.
There's a good discussion about this on bob is the oil guy. The bypass happens when the pressure differential between the input and output sides are greater than 15-20 psi. What this translates into exactly on your oil pressure itself, I don't know, but the filter works to pressures quite a bit higher than 20 psi. It's when the filter media can't flow enough oil that essentially it stops filtering and bypasses. This can occur for several reasons like, 1. the filter media can't flow as much as the pump is pumping (like at high RPM operation), 2. the filter media is partially clogged or 3. the oil is cold and thick, causing a temporary condition 1. Edit: Okay, I see what you're talking about now. That spring on the bottom that holds the filter media up is just that, something to hold the filter media in place. This is a way to seal the filter cartridge to the top of the housing without having to build everything to exact tolerances. Notice that the top metal end cap on the filter media assembly has a tapered opening so it can seal better. This spring is not intended as a bypass, it's just there because it lowers the cost of manufacturing over say making a machined filter housing to exact tolerances. Think like bearing preload. This also will work better for that application because the filter media will probably grow a little as it warms up and shrink as it cools. The spring will ensure it stays put in all conditions, kind of like the spring clamps on radiator hoses. There is only one bypass valve in there, and it's the little flap on the bottom.
Yes the big spring is just to seal the element to the cartridge some dont even have spring but just a bent sheet metal to take up the slack and put a constant pressure on the cartridge Tony is completely wrong here
@@legros731 Haha, he just released a correction video a few minutes ago. He's still making the claim that this spring can still behave as a bypass. I guess it's conceivable that it could, but I don't think it's intended for that purpose. At least he clarified when the bypass happens, which is only when there's a pressure differential on either side of the filter element.
@@randr10 on some filter there no spring there just a bend piece of sheets metal Filter are not meant to catch big chunk of metal or protect against bearing failure anyway and will rapidly clog opening the bypass and send all the shaving everywhere that why you find debris everywhere in the engine after spun bearing or oil related failure
I did a bit of work on filtering for big diesels years ago. I agree a spin on is very much part time. There are better ways of doing it. Full flow centrifigal filters were considered and in practice worked well but were expensive and never caught on. A seperate filter system was often installed, sometimes with its own pump to circulate oil through a number of filters simultaniously but this runs in bypass mode as well.
A co worker at a previous shop I worked at said back in the day Fram use to make their filters able to accept a toilet paper roll. I don't know the truth behind that but I thought it was interesting.
@@michaelshannon5051 that may have been the name. Fram was just the first name that popped into my head. That's pretty interesting haha single ply for the win
Way back when, Sears, Montgomery Wards and lots of auto parts sold conversion kits that “saved you money” by switching from a screw-on filter to a system that used a permanent canister that was built to fit a standard roll of toilet paper. Unscrew the top, pull out that nasty roll of TP and replace it with a fresh roll. Many of these stores had working display where you could watch nasty sludgy oil pumped into the “filter” and watch clean oil being pumped out. Snake oil salesman…
Hey Tony I know your not a dumb guy and you have a hell of a lot my experience than I do and I have a lot of respect for you but I believe you are mistaken. I asked about this when I was building my 327 chevy. I had read that it was a good idea to block Chevy's built in bypass valve. What my instructor told me the same thing that you comment section is telling you. The valve doesn't bypass whenever oil pressure is over 20lbs but it bypasses when there is a 20lbs difference in pressure between the two side of the valve. If you have 50lbs on both sides of the valve plus spring pressure that valve is staying shut. I believe it is the same with the spring in the oil filter. If the whole can has 50lbs of oil pressure the spring is holding the bypass shut. The valve is there to prevent loss of oil pressure to the bearings in the event of a clogged filter. Dirty oil is better than no oil after all. lots of older engines were never equipped with oil filters or if they where they only filtered 1/3 to 1/2 of the total oil flow but they did filter out some contaminants that could contribute to increased wear.
40 years ago, my worst oil filter story. I was working on a '72 Valiant (225/6; auto; still running bias-ply tires) and decided to change the oil and filter that afternoon. I had recently read that "prepping" your filter by pouring oil into it prior to screwing it on would provide maximum protection upon startup, as the filter element would be properly soaked in oil and would minize the time to become effective. I had drained the oil and removed the filter, but didn't really think about that procedure and how to reverse it. /6 owners know where this is going. I carefully poured some oil into the new filter element, and then headed over to the engine bay, whereupon I reached down - and recalled the oil filter is mounted vertically. Realizing my screwup, I tried pouring excess oil out of the filter into the engine before attempting to remount the new filter, but the damage had already been done: what a mess!
@@cromBumny A fun, quick tale from the Columbo/Colombo V12 days: throughout the late 70s-80s, it wasn't uncommon to come across a 300/330 for sale at a paltry $10-15K, simply because it required extensive servicing, and accessing the transmission required removal of much of the interior in order to remove the powertrain, which the owner wasn't prepared to pay for. And yes, it still doesn't make sense to me.
Volkswagen didn't deem filters necessary for their air cooled engines. There was a large screen to capture big pieces of engine assembly on their way thru, tho.
So when a person does an engine flush such as BG, most of them have directions as to not drive the vehicle. They don’t want the oil pressure to build to high as to not letting the oil filter, filter all the bad stuff, and not recirculating the bad stuff that got cleaned off. Hope I explained this right. I get what he said and I believe him because he’s got years of experience. Thanks for teaching me something today.
Hey tony. April fools already came and went. It's not an either or on the oil being filtered based on that bypass rating. Not an On/off deal. Even if it's against the spring, some oil is flowing through the filter media.
Right off the bat, you got a key fact wrong. The bypass valve (the one that sends unfiltered oil to the engine oil galleries) opens when there is 5-10 PSI ACROSS THE FILTER. Not total oil pressure. In other words (just for example) if the pressure going into the filter is 60 PSI, there’s a 2 psi drop across the media, and the output pressure is 58 psi… the bypass is CLOSED and the oil is being filtered! It only opens if the the oil pressure input is 60 psi and the output is 50 psi. There will be no indication on the pressure gauge when the bypass is open (usually when the oil is cold and thick and can’t get through the media easily.) The pressure relief valve (which limits max oil pressure) is in the pump and when it opens at 80 psi or whatever, it just sends oil back to the inlet of the pump, it doesn’t bypass the filter.
If they worked, back in the 1970s, the old dude in my hometown who worked for Ashland Oil wouldn't have been paid an "undisclosed amount" to retire early, to take their offer and run, and never mention the revolutionary filter he designed that cleaned up high-mileage oil and brought it back to like-new status. Even paid him extra to never tell a soul the chief component in his system was a roll of toilet paper.
The oil filter is designed for average person use, such as taking the kid's to school, shopping, not rally, drag, or track racing, thanks for sharing, all the best to yous and your loved ones
I would have NEVER known that while at the same time I knew it because I was aware oil filters had a bypass in them but I thought they only did a bypass if the filter was clogged. Thank you so much for sharing this.
Because that exactly how it work tony is wrong They work on differential pressure ie pressure drop across the filter element It could be 1000 psi and the bybass will stay close if both inlet and outlets pressure are the same The system pressure is irrelevant
A bypass oil filter works pretty good. 5 to 10 percent of the oil might drip through the filter. The oil that the so-called full-flow filter bypasses, is plumbed to the 2nd filter. It's kind of like a thick multilayer coffee maker filter. Some might also use layers of fine mesh screen. The kidney in a human body is a low pressure filter - when you have healthy BP. Low pressure gravity filtering is very effective. In a minute or so all of the oil in a motor will be cleaned at normal cruising speed. The problem is the Amsoil and similar bypass filters are kind of expensive - and pretty big. I change oil at 3,000 to 4,000 miles. If I were considering a 10,000 mile schedule, I'd look into a bypass filter. My '40s Mopars have smallish bypass filters, the Chrysler flatties in the '50s have full-flow filters. Another type of oil filter is the centrifugal type. There used to be an aftermarket bypass filter that used a roll of toilet paper. I'm doubtful, but these were used years ago. In those days the oil pan might be deep with six quart capacity so the sludge in non detergent oil would settle to the bottom.and hopefully stay there. Some oil pans had a removable plug that you could open and manually scrape away the sludge - maybe after kerosene was poured into the still warm engine.
i have been a professional transmission rebuilder for 40 years, and a mechanic longer than that. i just retired, and i have never thought about that. thank you, Tony!
New info for me, always thought the bypass was only for "plugged up media". Ok so the ultimate system would be a non bypassing metal screen type filter for the big stuff. But on top of that you would need "full by pass"(very tight filtering media) type of oil filter to filter out all the small stuff during normal driving.
Thanks for making us think about this. You have some good points but, engine oil pressure is normally determined by bearing clearances. Having back pressure at the bearings will minimize the differential pressure across the filter element. Even at 60 psi oil pressure the filter element may only have 0-10 psi differential. The large spring would not be compressed in most situations due to the pressure being equal within the oil filter shell. The small bypass on the bottom of the cartridge would open due to excessive differential pressure from a plugged oil filter. Also, don’t forget the oil filter adapter may also have an integral differential pressure bypass. SBC adapters do. Many plug them off to avoid unfiltered oil when cold. …Not sure that works as well as some would assume either.
This is why as a mechanic I always tell customers change your oil , don't listen to the factory 10 mi changes if you change at 3to 5 k your good if you ever had an engine apart , any kind. That someone's not changed the oil ,for way after due ,you would see why when you look in sump
I've looked through several comments and have yet to find anyone talking about the resistance to oil flow presented by the destination of the oil. That, so far as I know, would be the oil gallery. Wouldn't that cause the pressure on the output side of the filter to build up to a point nearly equal to the output pressure of the oil pump? (of course it would) I've seen several comments posted referring to "differential" pressure verses "static" pressure. (static being what you seem to be referring to, Uncle Tony) If the pressure going into the filter is, let's say, 40psi and the output going to the gallery has sufficient resistance (I sure hope so), then the output from the filter will build up to be nearly the same as the input from the pump. The only pressure drop across the media will be a direct result of the 1. flow of the oil and 2. the resistance of the media. The only time the bypass should be activated is when the engine is cold and first started up (no pressure in the gallery). Or, when the filter is clogged. Any other time, the oil is going to flow through the filter w/o activating the bypass. This scenario seems to be consistent with all of the technical articles I've read and totally consistent with my knowledge of fluid dynamics. I could be wrong.
I personally think the oil filter is flowing oil at all times. It’s just a matter of how much. when the oil is very cold and the filter is very dirty then yes most of the oil is going through the bypass so it won’t blow the filter media apart. However when the oil is 220 degrees and the oil filter is clean and the correct size for the flow of the particular oil pump then there won’t be enough resistance to activate the bypass in the first place . Let’s say you have a 55 gallon drum oil filter, built exactly the same way the bypass would never open at all.
Love your channel, Tony, but sorry to say this vid isn't up to your usual standards. There's a big difference between absolute pressure and differential pressure. Others have explained it succinctly in the comments here. Might want to re-think this one. COnsider too where the oil pressure sensor is located in the oiling system. On most engines, it's AFTER the oil filter. Consider what that means re gauge reading versus unknown(!) pump output pressure versus delta-P across the filter versus the delta-P needed to engage the filter bypass systems.
👍I’ve always changed my own oil w/ filter and I’ve never had an engine fail whatsoever. Since owning any brand of auto since 1983. Replaced oil every 3500-4500 miles. Top off if low between changes.
This was true of oil tech filters There are a lot of new filters that the spring tension does not allow this to happen also you can get a spec sheet from every mfg which will tell you the pressure that it will bypass I'm a diesel guy and there are cat, donaldson, royal purple and more where it has very high spring tensions and bypass is almost eliminated in high demand operation
I don’t agree with all your points but as for the intentional bypass: when oil is cold, especially conventional and or oil with high viscosity rating, the differential within the filter causes the bypass to open. This is good as it allows oil to flow to lubricate but bad as it’s not filtered. Low viscosity oil or synthetic oil will reduce the time the bypass is open. It also reduces the amount of oil loss through the pump relief valve meaning greater flow to lubricate. The filter media also plays a big part. The less restrictive, the less the bypass is required to open. Amsoil for instance uses nano technology in their filters which gives more passages through the filter element while retaining high quality filtration. These days we are told not to warm up our engines … just start and drive and it will warm up quicker. This is true but now we have a situation where the oil is thicker and because of the higher rpm due to driving, the pump relief valve is open relieving pressure which in turn reduces flow at the same time, the oil is not filtered since the bypass is open. As well, since the engine is cold, the computer sends more fuel to the cylinders. Fuel washes away oil so even less lubrication takes place in the cylinders causing wear. This is a bigger problem with direct injected engines. To reduce the situation of reduced flow and unfiltered oil, use a good quality synthetic oil and a good filter and let the engine warm up a couple of minutes or even a couple more if really cold before driving to give the oil a chance to thin down a bit and do it’s job as it is meant.
If you really want to filter your oil get a centrifugal filter in circuit. They spin 1000 rpm for every 10 psi oil pressure and force contaminants out of the oil and collected in the housing.
Tony ! You did not mention the one most important thing to allow people to rest easier! Any bypass predetermined X-psi pressure setting relies on that X-psi "pressure differential" to exist across the valve. It has nothing at all to do with observed gauge pressure. You can be at 100psi on the gauge amd not have a 7psi bypass flowing a single drop of oil so long as the "pressure differential " across the valve is below 7psi. Yes, as filter media blocks, flow is reduced, this increases pressure differential from one side of the valve to the other, once the limit of pressure differential is met, then the valve begins to flow, not befor and certainly not at any given point on the gauge. Other than that, good explanation.
When the engine is putting out more than 25 pounds of oil pressure, it does bypass a 25lb bypass spring. That doesn't mean that the oil filter is no longer filtering, it reduces the amount of oil that's filtered by a percentage. And that percentage can probably be as low as 25 to even 10%. But as long as there is oil pressure that reaches the outside of that filter some of it will still go through the filter. Most of them the oil is forced to the filter and then the bypass valve is at the other end of the filter head and is allowed to come up through the filter. Those with the bypass valve actually in the head end of the oil filter will filter a higher percentage of oil than those where the filter oil filter pushes down and the vast majority of the oil goes right back towards the engine instead of down the side of the filter which some of it will still do, just not by as much.
if the oil enters the side as stated, the hydrolic pressure is pushing on all sides of the element. its not going to move. it would have to enter from the center to work the way he said, which it doesn't enter the center. the bypass is the bottom valve and works off pressure differential not system pressure
Thats why I have Hambergers brand, dual pass oli filter boss with a full metal jacket filter in the first filter location. Paper on the 2nd filter location. No unfiltered oil through my motors!
I never knew that I've never caught a oil filter open thanks so much for the information A better reason to change your oil more often and keep it clean as possible Something I learned From what used to be older guys to me now I am the older guy They used to say clean oil when you put it in Clean oil when you take it out that means you're doing good Didn't give that as much thought as I did today after watching your video thanks a lot Uncle Tony
I almost paused the video early in and commented about Oberg, but I thought "No, UT knows about filters like Oberg, he'll mention them", and magically, you did! lol
Somewhere I have seen a test of filters - and bypass spring/valve was actually a significant difference in filter quality - more so than the actual filter membrane.
This is completely incorrect information. If an oil filter has a bypass valve rated at 8 PSID (The D is the key as it represents differential), this does not mean that when your oil pressure shows higher than 8 PSI, it's bypassing the oil filter. Your oil filter media allows oil to flow through up to a certain amount of pressure. If that pressure is 70 PSI and the PSI of the bypass valve is 8 PSI then said valve will not open until your oil pressure exceeds 78 PSI. There's an 8 pounds per square inch differential because of that bypass valve. A new oil filter will have very little resistance to the flow of oil. As your filter captures more and more contaminants, that resistance increases causing the PSI to increase in the oil filter. If you don't change your filter a few times, it's entirely possible that the filter media will eventually enough resistance to the flow of oil that the bypass will open during normal driving or even idle allowing oil to free-flow through the engine. Additionally, that big spring has nothing to do with the bypass valve. It's just to hold the media in place to keep manufacturing costs down. The bypass valve has its own internal spring.
Sorry Tony, but you're completely wrong on this. The spring is inside the filter housing, so it has the outlet oil pressure working with it. It will only open when the pressure differential between the inlet and outlet side of the filter rises above the spring pressure.
Considering the thin housing on the filter it now occurs to me it couldn't handle higher pressures inside the filter. Since oil flows to the bottom before traveling through the filter media, it could burst the outer shell if pressure hit 60 pounds and the media was partially clogged. That could be a serious issue at 20 below zero. And it might be why my 2012 Jeep with 3.7 engine requires 5W20 oil. I was a bit put off when I went to do my first oil change thinking that thin oil might not be protective enough, so I went with synthetic. But I take comfort in realizing that thinner oil gets to the top end a lot faster than thick oil.
I've always thought the bypass only kicked in when the filter was plugging. Because of not changing as often as you should. It makes no sense to me that your filter is only active at idle. If I knew that, I would find a filter that had no bypass until the filter was plugged. Motors wear and very small metal particles end up in the oil and need to be filtered out. Other wise the motor will not last very long. So what I am hearing can not be true. If it was, most mechanics would know about it and better oil filter systems would be mainstream. If I had to run more filters to get the flow I need without any bypass, I would. Motors are not cheap. Especially when you figure in the labor to remove and replace back into car. At idle, the crank is spinning a lot slower and not as likely to have the turbulance to lift heavy debris from the bottom of pan as say, a motor spinning at 3 to 7k rpms. If what Tony is saying is true, then having a filter that filters all the oil that passes through the can, motors would last millions of miles. So no, I think they are filtering until they start getting clogged.
I have a SBC 385 stroker (4.04"x3.75") in my Camaro. I use a K&N HP-6002 2-quart oil filter. It doesn't have a bypass or the anti-drain back valves. I also blocked the factory oil bypass in the block. All the oil goes through the filter. I use Amsoil Z-Rod 10W-30 oil. I only drive it in the warmer months.
LOL, I see vids comparing filters all the time and they never really mention the pressure bypass! This definitely needed to be said UT! Learned this during Mercruiser training many years ago. Good stuff UT! KUDOS!!!
That bypass valve is the reason I laugh at people who insist on pre-filling their oil filters through the small holes rather than the big one in the middle. As soon as they start the engine that oil goes through the bypass valve lol.
*@Uncle Tony* I know you know this, but you forgot to mention WHY there's a low pressure bypass in oil filters. For those who don't know though: that bypass system actually NEEDS to be there because above a certain PSI, the oil can't flow through the microscopic holes in the filter media fast enough, so they put a pre-determined PSI bypass in there to keep the oil pump's pressure from blowing out the filter media. It's not an ideal filter design, but without making the oil filter much, much larger to accommodate 40-60+ PSI of oil filtering capability, they put in an oil pressure bypass instead. Sadly, it's just a necessary byproduct of such a small screw-on filter design.
YES! Finally someone got it right!!
Haha forgot about that. Somehow that seems like it might not be so easy. I’ll bet the used filter would be softer than lanolin.🤪
Youre missing one important factor, flow rate of specific viscoty oil through filter media at what it is rated for in microns. Say a 30wt at 10cst "centistokes" rated at 200 degrees. Oil thins out as the engine warms so the bypass can function during a severe cold start when the oil is essentially a soft mushy brick in your oil pan if its conventional oil.
Gregory Lyan, nailed it !
@@rickpatterson7438 ive looked over so many brands and viscosities of oil and even some of the most top notch oils have a maximum permitted API viscosity of 6,600 at -30 degrees. They hit about 12 at 200 degrees. To go from 5k to just 10 thats how much oil thins out during warmup. Every day. Every trip. And that was an API rating for amsoil OE api certification.
The bypass works on differential pressure across the media and not just a static value. At 40 pounds pressure you may only exhibit 10 psi differential across that media, thus with a 20 psi setting for the bypass spring, the bypass remains closed. The bypass is open a lot on more or less any filter but its not based on the static pressure you read on your oil pressure gauge.
So if you don't mind can you answer a question or two. I own a 65 Mustang with a 302 that at cold start is at 82 psi. Once warm its around 40. It will drop below 30 at idle when good and warm. Am I filtering any oil at all? I know K&N sells two different filters. One I believe they advertise as ia high-flow, the other as a high filtration. I went with the high-flow because I didn't want to increase oil pressure. Any information you could give me would be appreciated thank you.
The differential also drops drastically as the engine warms up. Oil flow through the media increases as it thins out. At 200 degrees when the average 30wt oil is at its rated viscosity around like 10Cst. It goes through that media like water. And higher rpm shouldnt affect the filter flow unless the unload valve in the pump fails then it will likely blow the filter clean apart 😅.
I'll stick with my VW oem filters and not mind the cost , because the bypass is something nuts like close to 35-40psi.
Or any of their own supplier like mahle Bosch or mann.
@@MrTheHillfolk theres a good reason too. VW rated and licensed oils such as vw502 and vw505 can go as high up as 50wt oils om the hot side. Vw understood this and added such bypass requirements
@@BPattB i may be able to help you, oil weight is a factor here the reduction of pressure is the increase of flow. So when cold the pressure behind your bearings is 80psi when oil heats up it becomes more and more fluid and flows much greater volume. Thus at idle you could see only 30psi but at the same time the oil is flowing much faster to its destination and in greater volume depending on oil pump. Now 80psi is the limit inside your oil pump relief. The spring is limited at around that psi or is now overcoming that spring all together when cold. Take that measurement hot at operating temp of your thermostat, at roughly above idle preferably higher at like 1500-2krpm. That is your spring limit. At that temp your oil is flowing the fastest and easiest it cam and that just shows your pumps pressure limit but NOT its volume.
I'm having a hard time believing that the oil filter is functional pretty much only at idle and not during 2000rpm cruising. Because that would make the oil filter pretty pointless, and something gives me the feeling that people haven't been using oil filters for the last 100 years for no reason.
And you are correct and Tony messed up on this one. That large spring only seats the cartridge to the top of the can. Any pressure pushing down on the filter media is also pushing up from the bottom. The bypass is built into the filter media and uses a separate and smaller spring.
@Jared Lancaster Right. Oil filter takes everything from the pump. If the filter gets clogged, there’s a bypass mechanism, but that only works on differential pressure across the filter. UT stepped in it pretty hard here.
VW bug /Beetle never did have a paper one and they made milijons of them (@8min) ruclips.net/video/LJD28DD4fT4/видео.html
@@ChrisPBacon-ok7ir almost correct its the differential pressure between the inside and the outside of the filter media is equal the bypass is close only when the pressure drop across the filter media exceeds the bypass spring pressure will the valve open like in a clog filter condition or a cold start in 32f and lower
Bypass valve is closed 99% of the time the engine is running
Normally UT is spot on, but I think the spring reacting to the pressure differential before and after the filter versus the oil pressure of the engine is significant. It would seem that this would challenge UTs theory that no filtration is happening at highway speeds
When Tony said "its doing Zero Filtering" i disagree because the filter media is still under pressure of oil flow against spring
I've been mistaken before, but I was reasonably sure the bypass rating on those valves is calibrated for the _differential pressure_ across the inlet and outlet, not the overall pressure in the system. I have several vehicles that never have oil pressure below the bypass rating of the filter, which generally is something like 8-22psi depending on the application. The implication of that would be that the filter _never_ filters any oil at all. I find that difficult to believe... The motor oil on my non-filtered power equipment looks like tar after 50 hours and my filtered automotive engine oil can look like new for hundreds.
Tony is wrong on this, the pressure differential is absolutely different than the engines oil pressure he is referring to. The pressure that builds in the filter increases as the filter clogs with time and its internal pressure increases, at a point it will open the bypass valve. The main engine pressure is on the other side of the valve 😂. The top valve he shows is the oil drain back valve that prevents dry starts. He's really spreading misinformation here.
@@glitchtriple6 yes ,it's a differential situation
Yup 100% right, the spring is merely bypassing whatever oil cannot go through the filter, and that's the whole point of it.
Someone needs to market a transparent filter
No you are rigth he wrong this would make no sense if tony was rion this one it absolutely based on differential pressure and ther not 2 bypass valve this is just absurd
I am so old, I knew engineers at WIX that would throw hands when you called a pressure differential valve a bypass
You are 100% corrrect ... was a long term 'filtration engineer' That 'valve' prevents turbulence (higher resistance to oil flow inside the filter material) during momentary extreme engine rpm episodes ..... and clogged / dirty filters.
@@richh1576 did they give you one of these hats ?
Tony. You’re wrong. It’s a differential pressure valve that measures pressure drop across the media.
Engine Engineers aren’t stupid
Filter schmilter....my 55 year old VW is still on its original engine and only has a screen for catching chunks AND IT LIKES IT THIS WAY 😉
Exactly!!! There were a ton of them driving around, and all of them lasted longer than a yugo!!!
Is this the same VW air cooled engine that is well known for only lasting 50-60k miles under normal use ? And a major reason is that they have no oil filter ? Me thinks yes.
@@joncrisler6001 Has nothing to do with filtration...airflow to cylinder #3 is partially blocked by the oil cooler so it runs hotter. The airflow issue was fixed in '72 or so with an offset oil cooler and can be retrofitted to older engines
The air cooled VW oil and air filters work on physics. The sieve part stops the large chunks and the way the oil\air is forced to do a very sharp right angle turn makes the metal or dust get caught due to centrifugal force. It's how the South Africans enriched their uranium to build their bombs and fuel their two power stations.
Lol
Wow. He is totally wrong. That cartridge has a pressure balance on the top and bottom. That’s not how the bypass works. It acts on a pressure differential across the filter not what your actual oil pressure is.
The pressure differential that the spring acts on is between the outer media and inner, not top and bottom
@@UncleTonysGarage right but you showed the whole cartridge moving up and down which is wrong. Also your statements about it being in bypass mode is also wrong. The filter maybe has a 5-10psi drop across it so you oil pressure could be 60psi at 5000 rpm and the oil is still going thru the media. You should fix this video.
I never doubted you, but im sure it only opens the bypass when there is resistance in the media which causes a pressure differential
How would horizontal pressure cause vertical movement?
Sorry but this is completly wrong , the vavle works on pressure differential from the inlet of the filter to the outlet of the filter , so only if the pressure going in to the filter is 20 PSI higher then coming out it will bypass to ensure the engine gets oil if the filter is clogged for some reason.
Pretty sure I believe this explanation. A fairly consistent volume of oil needs to be flowing and filtration would only be bypassed when necessary.
And it does so via a separate bypass valve and spring in the bottom of the media cartridge. The large spring is just there to hole things together tight. Tony screwed up on this one.
Yes! usually agree with Tony but he entirely off- it’s pressure differential. A 20lb bypass could kick on at a 30>10 split but not 30>20. or open at 60>40, yet not at 60>45
I thought these things operated on pressure differentials - i.e. the difference between the pressure going in and the pressure going out. The setting of 10 to 20 PSI (actually PSID) would make a bit more sense to me.
This is the correct answer. The pressure differential is not the same as the pressure being applied by the pump.
Yeah most people don't understand between differential and static pressure. If there is 40 pounds static but only 10 pounds differential across the media, with a 15 pound spring the bypass remains closed. So this entire video is incorrect lol
Why does the bypass exist at all? Is it there to let more oil flow at high rpm so engine doesnt starve of oil or something?
It does
Yes what Bill said is correct its just unfortunate that this disinformation will reach a lot of uneducated people in a cult format. Lubrication engineers have spent decades designing these filters and engines. Its called "full flow lubrication" for a reason set apart from the 1950s bypass systems which i do have on old flatheads. Its an honest mistake and im sure as close as tony is to big brains like David vizard someone may be able to correct him and this video taken down.
How to keep your oil clean. Change it !
Sorry but the spring or stamped steel butterfly is in the can to hold the filter media in place. It has nothing to do with bypass.
Agree 100% UT is wrong
Oh great one, I find I must disagree. The bypass operates on the differential pressure between the inlet (oil pump outlet) and the outlet (the rest of the engine). (If what you are saying was true, if an oil filter had no media, there would be no oil pressure developed.) So, if a filter has a 20 psi bypass valve, there must be 20 psi of backpressure developed by the media before the bypass will open. This will only happen if the media is getting pretty plugged. This is why they are called full flow oil filters, because they filter all oil after the oil pump and before the engine. The older cars 216 - 235 Chev six, for example) were built without an oil filter. If you ordered the oil filter option, they bled off a little oil after the pump, which was filtered, then sent back to the oil pan. This reduced the oil pressure, but not by much. Only a little of the oil was thus filtered, but of course eventually it all got filtered.
The pressure is determined largely by how tight the engine's tolerance are - hence Bottle Rocket having practically none. If the filter were causing that much back pressure it would be severely limiting the oil supply to the engine.
@@DuckyHunter812 Please forgive my ignorance - I never was the brightest bulb on the tree. I didn't make my point clearly, which is a common problem with the written word. What I was trying to say was: the oil pressure generated by the engine (bearing clearances, etc) doesn't matter. If the oil filter media generates > 20 psi backpressure (due to high viscosity oil, plugged media, etc), the bypass will start to open, assuring adequate flow of oil to the engine, although obviously unfiltered, the thought being that adequate flow of even unfiltered oil is better than inadequate flow of filtered oil. (I suppose on reading this later I will find it inadequate too, but it 's the best I can do right now.)
Wouldn't that internal filter spring only act on the internal back pressure produced by the filter media itself? The overall system oil pressure would act on both sides of the oil filter. That way if the media plugs, it won't starve the motor.
So downstream oil pressure wouldn't affect free flow through the media. If media is causing back pressure, oil can bypass
i've had a filter plug and destroy an engine before so idk about all that
@@donbehatin If the oil was dirty enough to clog a filter maybe THAT is what killed the engine.
The spring at the bottom is not the "bypass". That spring is there only to hold the filter cartridge tightly against the top of the filter can. The actual bypass valve is inside the filter cartridge at the bottom.
Agree, there is only 1 "by-pass" or pressure differential valve. That big heavy spring is to seat the media to the can.
@@scrappy7571 why would they use a spring then, and not just a spacer ?
@@kellismith4329 With a spring, the tolerances can be sloppy. A spacer would require precise parts to be made, spring is cheaper.
Correct. I look forward to another video from Tony to clear this up. Hey, everyone is wrong once in awhile.
I would say it's a second bypass as a product of design. It's not that it pushes the filter media down compressing the spring, but oil could get forced between where the two surfaces meet at the top of the pressure was high enough. How much that is relative to the main bypass IDK.
15 years as a BMW Motorcycle tech/service/parts manager I have had to explain this a thousand times. Mostly to the people that spin a fram from a toyota onto a BMW motorcycle to save money because "it spins right on" not realizing that there is a 60psi difference between them. Many engines died, to bring them this information...
If the filter is full of oil that same amount of pressure is also acting on the bottom of the filter media assembly, pushing it upward in the same direction as the spring. Just a thought. Not as simple as just the incoming oil pushing down against the bypass spring.
Exactly, the cartridge acts different once it is flooded and at equal pressure
Pascal’s law.
A high velocity, the oil will push down some. There's 3 things going on here. But sometimes that big spring is a leaf instead. I like oversize filters. Probably a waste but I'm thinking about cold flow rates. My Penny's worth. I'm just a nerd.
Tempted to dent the cap and boost the spring pressure now, turn it from an outtie to an innie lol. The flap by the threads is an anti drain back. Heard it prevents it all from going to the bottom end by just gravity.
First the spring he talk about is not the bypass valve it's the center button he point at the end of the video
Denting the filter will do nothing
And it work on differential pressure(pressure drop)what he said make no sense
@@legros731 He put up a new one correcting things. The spring is the pressure differential bypass, it allows the media cartridge to move out of the way above 20 psi.
The oil pressure flow that comes inside the oil filter applys equally at the top surface and at the bottom surface of the filter cartridge, so the bottom spring always overcome and maintain the cartridge against the top, made with a steel wire the bottom spring is the cheapest solution used to get top cartridge sealing as it force the cartridge against the top rubber seal (also called anti-drain back seal). This avoid oil from going directly to the exit of the cartridge without filtration. The cartridge never move inside . The bypass when it exists acts when differential pressure due to media clogging allows oil flow to go through it because it is less restrictive than going through the média. When there is not bypass in the oil filter the bypass is located in the oil filter mount.
I've been changing oil since 1987 and this is the first time I've thought of that. Thanks uncle Tony!
that big lower spring it's just to keep the filtering element snugly sealed against the top plate... have in mind that oil pressure once passing through the rubber anti-return membrane acts in all filter element surfaces (top + lower plates + filtering media). The only bypass is that small hole - at lower side of the filtering element.
Bingo, someone finally stated the true job of what tony mistakenly called a bypass valve. That springs job is to hold the element up. Any oil pressure pushing The element down against that spring will also be pushing up on the element with the same amount of force. That’s why there’s an actual bypass valve in the bottom of the element that will open when the media becomes restricted. I was taught when attending a very expensive seminar given by a filter manufacturer.
@@davidleonard8369 100% correct! UT is wrong.
@@davidleonard8369 why is it a spring then ? If you wanted to hold the cartridge stationary you could use anything much cheaper than a mfr’d spring
@@kellismith4329 the spring is a very inexpensive way to hold the element up. Not only does the same spring work for multiple different filters it requires no special installation or tooling as it is simply dropped in during assembly. It also will automatically compensate for thermal expansion and contraction. So in essence the spring is simply the best way to do the job.
My 1974 VW Bettle, which I purchase new in 1974, never used an oil filter. All it had was a screen. When I changed the valve cover gaskets at 95K the insides were spotless. Take that for what its worth.
Now we need Gale Banks to make a clear oil filter so we can see if this is true.
I found it very interesting that on my car in 1955 an engine oil filter was an add on option.
My father said his '53 Pontiac Chieftain had a "built-in" oil filter. While I remember that car from when I was a kid, I certainly don't remember seeing any sort of oil filter. My father did start using detergent oil as soon as it came out.
First off i enjoy your videos... The function of the coil spring in the bottom is to keep the entire assembly inside pushed together... The bypass is the hole in the bottom of the end cap that is spring loaded with a predetermined pressure spec'ed for the application... Some filters don't have bypasses at all due to it being internal to the engine!! The full oil pressure of your engine is not rushing through the filter bypass, it is the static difference or the left over pressure that could not make it's way through the filtering element because of either restriction, cold start or high viscosity oil..!! Bottom line is use a nonrestrictive filter, change your oil and filter regularly, use the correct viscosity of oil and the oil filter will rarely be in bypass mode!! Love your channel btw!!
Wish you could do a talk on the old Frantz filter system. Some called it the 'toilet paper' system. One roll and one quart of oil! We also went to a dry-sump system on anything that drove to the strip, then ran, then drove home.
Frantz filter systems are back.
So I might as well use the cheapest filter and continue to change my oil every 3 thousand miles like I have been doing since I bought it new. Thanks for this. I had no idea.
so I did a ton of research on this, using a larger filter allows more oil to pass through the media without opening the bypass. for instance, my 94 supra has a tiny oil filter, the upgrade that people use is to a first gen tundra filter, the upgrade tundra owners upgrade to lexus lx470 filters lol. so my supra has a 6 inch long oil filter from a lx470, and the only upgrade from there would be a 8-10 inch wix commercial truck filter without a bypass. YOU can literally figure out the filter specifications (thread pitch, length, diameter, bypass psi) your oem filter is, cross-reference this info from frame to wix or other companies filter databases and just size up to wherever. you don't necessarily need the filter bypass if you live in a hot climate or you only drive the specific vehicle during good times of the year. also having more filter media allows more paths for the oil to flow without building up pressure and triggering the bypass valve!
Toyota would use #241 filters but I could use #195 or 4457 , even the large 4670 or #1 for Ford V 8.
Hi T, hate to step on your turf, however, with great respect, that internal bypass is in case the filter/paper/media, gets plugged. The oil will then "bypass" the filter/paper/media, and flow directly to the engine and not blowup the filter can or starve the engine for oil, thereby causing a catastrophic (really bad) loss/lack of oil. Oil is always flowing through the filter, it does not matter how much oil pressure there is. It depends on the pressure difference between both sides of the filter (inlet vs outlet) or backpressure, when the difference gets to great, the spring is pushed down. Also there is the oil pump bypass valve in the oil pump, it is not a pressure relief valve, if there is too much backpressure in the filter the valve will bypass the oil directly to the engine. Of course on newer engines they also control the oil pressure electronically, but there is always the mechanical bypass, just in case.
Blue Mule
PS shout out to LS, just expanding on his/her thoughts
Different part number filters are supposed to have different bypass psi ratings per oem specs. That said you would have to test each out to see. The race specific filters normally have a bypass that is much higher.
Question: Does not the oil pressure act on the bottom of the filter element (pushing up) as well as pushing down onto the top of the element? If true, then the spring would make a percentage of the oil go through the element. Assuming that the element is not clogged.
Yes, the filter is always filtering some of the oil, Not ALL is bypassed, there's no way it can be
If it's not restricted then there is always a portion of the oil flowing through the filter even if the bypass spring is opened.
Correct. The pressure pushing down on the top of the filter canister also pushes down on the oil under the filter canister, so the pressures on the top and bottom are always equal. That's why the actual bypass valve is inside the filter canister.
The spring shown in this video is NOT the bypass spring!
@@ChrisPBacon-ok7ir Quite right!
They bypass but it is not a binary on-off. If the pressure is too high, some of the oil bypasses the filter. You don't need 100 percent filtering anyway.
The squirrels are getting slower.
Great information as always! Thanks, UT, for keeping on grinding!
Pressure Differential is what causes the bypass, not oil gallery pressure.
You are mistaken. This is why. If the filter element has 50 psi on the pump side, that is pressing against the element, sure, but if there is 49 psi after the element, this is pushing back against it so the bypass only sees that 1 psi difference, not the whole 50 psi. John Cardogan was big enough to publish a retraction the other day. Let's see if you do too. ruclips.net/video/djuy1KFOTLY/видео.html
From Leo: Good report Tony. Filters are a good thing and they help. (I had an old Dodge that had a canister filter on the fender and it only filtered a little oil on return). If you keep the oil changed, a filter is not even needed. I drove over 90,000 miles on an XS 650 Yamaha that does not even have a filter, just a bronze screen in the sump to strain out the big pieces. The guy I sold it to rode it all the way to Seattle from Chicago that week and was still riding it a year later. CB series Honda's just had a centrifugal cup on the end of a shaft that trapped any metal chips behind a little lip in the spinning cup.
WOW!!!! Talk about teaching an old dog (that's me @ 69 yr's of age) new tricks. Thanks Uncle Tony, your the best. God bless.
UTG you're a great guy with a ton of useful knowledge, but I think you are wrong on this one. The inflow oil pressure actually helps the spring (adds pressure ) keep the element tight against the end plate. The push valve at the bottom allows bypass if the filter is clogged. The pressure relief valve in the oil pump is in place to dump excessive pressure on cold startup when viscosity is high. Its' called full flow filtration for a reason.
Tony, I’ve never thought about this and it makes perfect sense. That’s why you see exploded/shredded parts in valleys and pans. Wow. As an old shade tree guy ((76) I’ve never thought of this. And of course there’s no mention on oil filter specs noting the psi rating on the by pass valves. Good one Tony.
You been fooled or tony is dumb on this one
The valve work on differential pressure ie pressure drop across the filter media
System pressure is irrelevant
I change my filter about halfway through my oil change. Been doing it for about 30 years. It doesnt cost much when you buy them by the case on sale. And you never have to worry about your filter being very dirty. Cheap insurance
Thanks UT. I've worked on cars and even in a parts store but never knew this.
you still dont!
And you still don't because he wrong as fuck lol
The Broken Life is correct "... those valves is calibrated for the differential pressure across the inlet and outlet, not the overall pressure in the system." As a retired Aerospace Engineer with over 35 years of oil system designs on jet engines, reciprocating radial piston engines and helicopter gearboxes including the JSF Lift-Fan gearbox, the oil filter can be a "full flow" design which filters 100% of the oil flow (when the oil is not as thick as molasses) or a non-full flow design. All good filters should have a "by-pass" valve to by-pass the filter when the "pressure drop across the filter" exceeds the set point of the valve. This will happen when the filter media catches too much contaminates (in service too long or a catastrophic failure) or the oil flow rate and /or oil viscosity exceeds the filter medias surface area to permit adequate flow without restricting the flow. I would guess most modern cars (since the 1960") have an OEM oil filter similar to that show on the Fram website - having an "anti-drain back "valve" and filter media "by-pass" valve or a "keep oil pressure in the engine" provision. www.fram.com/products/oil-filters/titanium
Then again, I'm assuming all the OEM engine designers know how critical, clean and pressurized oil is to the successful operation of their engines are.
I like your videos Uncle Tony but felt I needed to put my wooden Nickle into this video. My apologies if I'm wrong. OBTW, my wife says I'm never right - does that mean I'm never wrong? LoL
I like the metal reusable filters for this reason. Oil flow is faster over a metalic mesh. Because the media is stiffer the bypass is also higher pressure. They do have a larger micron rating however. So you win some you lose some.
I am not talking about the screen type, but the catrige style which fits into a typical looking screw on filter
My dad worked at one of the major filter manufacturers for over 30 years. He said the engineers told him that after about 500 miles the media is clogged to the point that its in full bypass all the time anyway.
Well I'm blown away on that for sure
There's a good discussion about this on bob is the oil guy. The bypass happens when the pressure differential between the input and output sides are greater than 15-20 psi. What this translates into exactly on your oil pressure itself, I don't know, but the filter works to pressures quite a bit higher than 20 psi. It's when the filter media can't flow enough oil that essentially it stops filtering and bypasses. This can occur for several reasons like, 1. the filter media can't flow as much as the pump is pumping (like at high RPM operation), 2. the filter media is partially clogged or 3. the oil is cold and thick, causing a temporary condition 1.
Edit: Okay, I see what you're talking about now. That spring on the bottom that holds the filter media up is just that, something to hold the filter media in place. This is a way to seal the filter cartridge to the top of the housing without having to build everything to exact tolerances. Notice that the top metal end cap on the filter media assembly has a tapered opening so it can seal better. This spring is not intended as a bypass, it's just there because it lowers the cost of manufacturing over say making a machined filter housing to exact tolerances. Think like bearing preload. This also will work better for that application because the filter media will probably grow a little as it warms up and shrink as it cools. The spring will ensure it stays put in all conditions, kind of like the spring clamps on radiator hoses. There is only one bypass valve in there, and it's the little flap on the bottom.
Yes the big spring is just to seal the element to the cartridge some dont even have spring but just a bent sheet metal to take up the slack and put a constant pressure on the cartridge
Tony is completely wrong here
@@legros731 Haha, he just released a correction video a few minutes ago. He's still making the claim that this spring can still behave as a bypass. I guess it's conceivable that it could, but I don't think it's intended for that purpose. At least he clarified when the bypass happens, which is only when there's a pressure differential on either side of the filter element.
@@randr10 on some filter there no spring there just a bend piece of sheets metal
Filter are not meant to catch big chunk of metal or protect against bearing failure anyway and will rapidly clog opening the bypass and send all the shaving everywhere that why you find debris everywhere in the engine after spun bearing or oil related failure
Thanks Uncle Tony! Next time I do oil change on my car I am going to try and do "oil filter delete" and just change oil more frequently.
Like my wife's 1950 230 6 ,partial filter it gets dirty quick.
I’ve suspected this!
The only time the bypass comes into play is if the filter media is totally clogged. Even on cold starts the differential is only a few psi different.
I did a bit of work on filtering for big diesels years ago. I agree a spin on is very much part time. There are better ways of doing it. Full flow centrifigal filters were considered and in practice worked well but were expensive and never caught on. A seperate filter system was often installed, sometimes with its own pump to circulate oil through a number of filters simultaniously but this runs in bypass mode as well.
So……. Tony your saying smash the bottom of the filter to collapse the spring right 😅😂
A co worker at a previous shop I worked at said back in the day Fram use to make their filters able to accept a toilet paper roll. I don't know the truth behind that but I thought it was interesting.
Dont know about Fram but Frantz had a system that used toilet paper. had that system on my 63 dodge 318 poly
@@michaelshannon5051 that may have been the name. Fram was just the first name that popped into my head. That's pretty interesting haha single ply for the win
I’ve heard that but I have a hard time believing it, try pushing oil thru a roll of tp, good luck.
Way back when, Sears, Montgomery Wards and lots of auto parts sold conversion kits that “saved you money” by switching from a screw-on filter to a system that used a permanent canister that was built to fit a standard roll of toilet paper. Unscrew the top, pull out that nasty roll of TP and replace it with a fresh roll. Many of these stores had working display where you could watch nasty sludgy oil pumped into the “filter” and watch clean oil being pumped out. Snake oil salesman…
Have to remember to remove the cardboard core
Hey Tony I know your not a dumb guy and you have a hell of a lot my experience than I do and I have a lot of respect for you but I believe you are mistaken. I asked about this when I was building my 327 chevy. I had read that it was a good idea to block Chevy's built in bypass valve. What my instructor told me the same thing that you comment section is telling you. The valve doesn't bypass whenever oil pressure is over 20lbs but it bypasses when there is a 20lbs difference in pressure between the two side of the valve. If you have 50lbs on both sides of the valve plus spring pressure that valve is staying shut. I believe it is the same with the spring in the oil filter. If the whole can has 50lbs of oil pressure the spring is holding the bypass shut. The valve is there to prevent loss of oil pressure to the bearings in the event of a clogged filter.
Dirty oil is better than no oil after all. lots of older engines were never equipped with oil filters or if they where they only filtered 1/3 to 1/2 of the total oil flow but they did filter out some contaminants that could contribute to increased wear.
Interesting information. Another reason to use the dipstick and keep an eye on the condition of the oil.
Interesting false info
The valve work on differential pressure across the filter element
Ie pressure drop
What he said make absolutely no sense
That’s why I use magnets on the pan and filter
40 years ago, my worst oil filter story.
I was working on a '72 Valiant (225/6; auto; still running bias-ply tires) and decided to change the oil and filter that afternoon. I had recently read that "prepping" your filter by pouring oil into it prior to screwing it on would provide maximum protection upon startup, as the filter element would be properly soaked in oil and would minize the time to become effective.
I had drained the oil and removed the filter, but didn't really think about that procedure and how to reverse it.
/6 owners know where this is going.
I carefully poured some oil into the new filter element, and then headed over to the engine bay, whereupon I reached down - and recalled the oil filter is mounted vertically.
Realizing my screwup, I tried pouring excess oil out of the filter into the engine before attempting to remount the new filter, but the damage had already been done: what a mess!
Old Ferrari (Columbo engines) have inverted oil filters. Seems dumb to me...that is rhe screwing side faced down, so you can't prefilled the filter
@@cromBumny A fun, quick tale from the Columbo/Colombo V12 days: throughout the late 70s-80s, it wasn't uncommon to come across a 300/330 for sale at a paltry $10-15K, simply because it required extensive servicing, and accessing the transmission required removal of much of the interior in order to remove the powertrain, which the owner wasn't prepared to pay for.
And yes, it still doesn't make sense to me.
Volkswagen didn't deem filters necessary for their air cooled engines. There was a large screen to capture big pieces of engine assembly on their way thru, tho.
My small block is 40- 60 lbs all the time so this is quite an eye opener
So when a person does an engine flush such as BG, most of them have directions as to not drive the vehicle. They don’t want the oil pressure to build to high as to not letting the oil filter, filter all the bad stuff, and not recirculating the bad stuff that got cleaned off. Hope I explained this right. I get what he said and I believe him because he’s got years of experience. Thanks for teaching me something today.
A friend's son in law changed oil and filter. Light stayed on. Kept driving it. Motor seized. Hadn't removed shrink wrap around filter.
Hey tony. April fools already came and went.
It's not an either or on the oil being filtered based on that bypass rating. Not an On/off deal. Even if it's against the spring, some oil is flowing through the filter media.
Right off the bat, you got a key fact wrong. The bypass valve (the one that sends unfiltered oil to the engine oil galleries) opens when there is 5-10 PSI ACROSS THE FILTER. Not total oil pressure. In other words (just for example) if the pressure going into the filter is 60 PSI, there’s a 2 psi drop across the media, and the output pressure is 58 psi… the bypass is CLOSED and the oil is being filtered! It only opens if the the oil pressure input is 60 psi and the output is 50 psi. There will be no indication on the pressure gauge when the bypass is open (usually when the oil is cold and thick and can’t get through the media easily.) The pressure relief valve (which limits max oil pressure) is in the pump and when it opens at 80 psi or whatever, it just sends oil back to the inlet of the pump, it doesn’t bypass the filter.
If they worked, back in the 1970s, the old dude in my hometown who worked for Ashland Oil wouldn't have been paid an "undisclosed amount" to retire early, to take their offer and run, and never mention the revolutionary filter he designed that cleaned up high-mileage oil and brought it back to like-new status. Even paid him extra to never tell a soul the chief component in his system was a roll of toilet paper.
Those filters are sold still today. Frantz!
@@TheMajictech I've seen them sold for Air Compressors and Pneumatic water filters but not oil. Where can they be had?
The oil filter is designed for average person use, such as taking the kid's to school, shopping, not rally, drag, or track racing, thanks for sharing, all the best to yous and your loved ones
I would have NEVER known that while at the same time I knew it because I was aware oil filters had a bypass in them but I thought they only did a bypass if the filter was clogged. Thank you so much for sharing this.
Because that exactly how it work tony is wrong
They work on differential pressure
ie pressure drop across the filter element
It could be 1000 psi and the bybass will stay close if both inlet and outlets pressure are the same
The system pressure is irrelevant
A bypass oil filter works pretty good. 5 to 10 percent of the oil might drip through the filter. The oil that the so-called full-flow filter bypasses, is plumbed to the 2nd filter. It's kind of like a thick multilayer coffee maker filter. Some might also use layers of fine mesh screen.
The kidney in a human body is a low pressure filter - when you have healthy BP. Low pressure gravity filtering is very effective. In a minute or so all of the oil in a motor will be cleaned at normal cruising speed.
The problem is the Amsoil and similar bypass filters are kind of expensive - and pretty big.
I change oil at 3,000 to 4,000 miles. If I were considering a 10,000 mile schedule, I'd look into a bypass filter.
My '40s Mopars have smallish bypass filters, the Chrysler flatties in the '50s have full-flow filters. Another type of oil filter is the centrifugal type.
There used to be an aftermarket bypass filter that used a roll of toilet paper. I'm doubtful, but these were used years ago.
In those days the oil pan might be deep with six quart capacity so the sludge in non detergent oil would settle to the bottom.and hopefully stay there. Some oil pans had a removable plug that you could open and manually scrape away the sludge - maybe after kerosene was poured into the still warm engine.
i have been a professional transmission rebuilder for 40 years, and a mechanic longer than that. i just retired, and i have never thought about that. thank you, Tony!
New info for me, always thought the bypass was only for "plugged up media". Ok so the ultimate system would be a non bypassing metal screen type filter for the big stuff. But on top of that you would need "full by pass"(very tight filtering media) type of oil filter to filter out all the small stuff during normal driving.
Thanks for making us think about this. You have some good points but, engine oil pressure is normally determined by bearing clearances. Having back pressure at the bearings will minimize the differential pressure across the filter element. Even at 60 psi oil pressure the filter element may only have 0-10 psi differential.
The large spring would not be compressed in most situations due to the pressure being equal within the oil filter shell.
The small bypass on the bottom of the cartridge would open due to excessive differential pressure from a plugged oil filter.
Also, don’t forget the oil filter adapter may also have an integral differential pressure bypass. SBC adapters do. Many plug them off to avoid unfiltered oil when cold. …Not sure that works as well as some would assume either.
This is why as a mechanic I always tell customers change your oil , don't listen to the factory 10 mi changes if you change at 3to 5 k your good if you ever had an engine apart , any kind. That someone's not changed the oil ,for way after due ,you would see why when you look in sump
I always thought the bypass feature on an oil filter was there in case the filter paper got clogged. That way the engine doesn't starve for oil.
I've looked through several comments and have yet to find anyone talking about the resistance to oil flow presented by the destination of the oil. That, so far as I know, would be the oil gallery. Wouldn't that cause the pressure on the output side of the filter to build up to a point nearly equal to the output pressure of the oil pump? (of course it would) I've seen several comments posted referring to "differential" pressure verses "static" pressure. (static being what you seem to be referring to, Uncle Tony) If the pressure going into the filter is, let's say, 40psi and the output going to the gallery has sufficient resistance (I sure hope so), then the output from the filter will build up to be nearly the same as the input from the pump. The only pressure drop across the media will be a direct result of the 1. flow of the oil and 2. the resistance of the media. The only time the bypass should be activated is when the engine is cold and first started up (no pressure in the gallery). Or, when the filter is clogged. Any other time, the oil is going to flow through the filter w/o activating the bypass. This scenario seems to be consistent with all of the technical articles I've read and totally consistent with my knowledge of fluid dynamics. I could be wrong.
I personally think the oil filter is flowing oil at all times. It’s just a matter of how much. when the oil is very cold and the filter is very dirty then yes most of the oil is going through the bypass so it won’t blow the filter media apart. However when the oil is 220 degrees and the oil filter is clean and the correct size for the flow of the particular oil pump then there won’t be enough resistance to activate the bypass in the first place . Let’s say you have a 55 gallon drum oil filter, built exactly the same way the bypass would never open at all.
Love your channel, Tony, but sorry to say this vid isn't up to your usual standards. There's a big difference between absolute pressure and differential pressure. Others have explained it succinctly in the comments here. Might want to re-think this one. COnsider too where the oil pressure sensor is located in the oiling system. On most engines, it's AFTER the oil filter. Consider what that means re gauge reading versus unknown(!) pump output pressure versus delta-P across the filter versus the delta-P needed to engage the filter bypass systems.
👍I’ve always changed my own oil w/ filter and I’ve never had an engine fail whatsoever. Since owning any brand of auto since 1983. Replaced oil every 3500-4500 miles. Top off if low between changes.
This was true of oil tech filters There are a lot of new filters that the spring tension does not allow this to happen also you can get a spec sheet from every mfg which will tell you the pressure that it will bypass I'm a diesel guy and there are cat, donaldson, royal purple and more where it has very high spring tensions and bypass is almost eliminated in high demand operation
I don’t agree with all your points but as for the intentional bypass: when oil is cold, especially conventional and or oil with high viscosity rating, the differential within the filter causes the bypass to open. This is good as it allows oil to flow to lubricate but bad as it’s not filtered. Low viscosity oil or synthetic oil will reduce the time the bypass is open. It also reduces the amount of oil loss through the pump relief valve meaning greater flow to lubricate. The filter media also plays a big part. The less restrictive, the less the bypass is required to open. Amsoil for instance uses nano technology in their filters which gives more passages through the filter element while retaining high quality filtration. These days we are told not to warm up our engines … just start and drive and it will warm up quicker. This is true but now we have a situation where the oil is thicker and because of the higher rpm due to driving, the pump relief valve is open relieving pressure which in turn reduces flow at the same time, the oil is not filtered since the bypass is open. As well, since the engine is cold, the computer sends more fuel to the cylinders. Fuel washes away oil so even less lubrication takes place in the cylinders causing wear. This is a bigger problem with direct injected engines. To reduce the situation of reduced flow and unfiltered oil, use a good quality synthetic oil and a good filter and let the engine warm up a couple of minutes or even a couple more if really cold before driving to give the oil a chance to thin down a bit and do it’s job as it is meant.
If you really want to filter your oil get a centrifugal filter in circuit. They spin 1000 rpm for every 10 psi oil pressure and force contaminants out of the oil and collected in the housing.
I haven't heard this in a long long time. You rock Uncle Tony!
Not all oil filters have a bypass.
Tony ! You did not mention the one most important thing to allow people to rest easier!
Any bypass predetermined X-psi pressure setting relies on that X-psi "pressure differential" to exist across the valve.
It has nothing at all to do with observed gauge pressure.
You can be at 100psi on the gauge amd not have a 7psi bypass flowing a single drop of oil so long as the "pressure differential " across the valve is below 7psi.
Yes, as filter media blocks, flow is reduced, this increases pressure differential from one side of the valve to the other, once the limit of pressure differential is met, then the valve begins to flow, not befor and certainly not at any given point on the gauge.
Other than that, good explanation.
When the engine is putting out more than 25 pounds of oil pressure, it does bypass a 25lb bypass spring. That doesn't mean that the oil filter is no longer filtering, it reduces the amount of oil that's filtered by a percentage. And that percentage can probably be as low as 25 to even 10%. But as long as there is oil pressure that reaches the outside of that filter some of it will still go through the filter. Most of them the oil is forced to the filter and then the bypass valve is at the other end of the filter head and is allowed to come up through the filter. Those with the bypass valve actually in the head end of the oil filter will filter a higher percentage of oil than those where the filter oil filter pushes down and the vast majority of the oil goes right back towards the engine instead of down the side of the filter which some of it will still do, just not by as much.
if the oil enters the side as stated, the hydrolic pressure is pushing on all sides of the element. its not going to move. it would have to enter from the center to work the way he said, which it doesn't enter the center. the bypass is the bottom valve and works off pressure differential not system pressure
Thats why I have Hambergers brand, dual pass oli filter boss with a full metal jacket filter in the first filter location. Paper on the 2nd filter location. No unfiltered oil through my motors!
I never knew that I've never caught a oil filter open thanks so much for the information A better reason to change your oil more often and keep it clean as possible Something I learned From what used to be older guys to me now I am the older guy They used to say clean oil when you put it in Clean oil when you take it out that means you're doing good Didn't give that as much thought as I did today after watching your video thanks a lot Uncle Tony
Thank you, thank you, thank you. I've been trying to explain this to customers forever!
I almost paused the video early in and commented about Oberg, but I thought "No, UT knows about filters like Oberg, he'll mention them", and magically, you did! lol
Somewhere I have seen a test of filters - and bypass spring/valve was actually a significant difference in filter quality - more so than the actual filter membrane.
This is completely incorrect information. If an oil filter has a bypass valve rated at 8 PSID (The D is the key as it represents differential), this does not mean that when your oil pressure shows higher than 8 PSI, it's bypassing the oil filter. Your oil filter media allows oil to flow through up to a certain amount of pressure. If that pressure is 70 PSI and the PSI of the bypass valve is 8 PSI then said valve will not open until your oil pressure exceeds 78 PSI. There's an 8 pounds per square inch differential because of that bypass valve.
A new oil filter will have very little resistance to the flow of oil. As your filter captures more and more contaminants, that resistance increases causing the PSI to increase in the oil filter. If you don't change your filter a few times, it's entirely possible that the filter media will eventually enough resistance to the flow of oil that the bypass will open during normal driving or even idle allowing oil to free-flow through the engine.
Additionally, that big spring has nothing to do with the bypass valve. It's just to hold the media in place to keep manufacturing costs down. The bypass valve has its own internal spring.
Sorry Tony, but you're completely wrong on this. The spring is inside the filter housing, so it has the outlet oil pressure working with it. It will only open when the pressure differential between the inlet and outlet side of the filter rises above the spring pressure.
A buddy of mine and I talked about this 40 years ago that an Oberg screen filter would be superior to a paper spin on filter.
Considering the thin housing on the filter it now occurs to me it couldn't handle higher pressures inside the filter.
Since oil flows to the bottom before traveling through the filter media, it could burst the outer shell if pressure hit 60 pounds and the media was partially clogged. That could be a serious issue at 20 below zero. And it might be why my 2012 Jeep with 3.7 engine requires 5W20 oil. I was a bit put off when I went to do my first oil change thinking that thin oil might not be protective enough, so I went with synthetic. But I take comfort in realizing that thinner oil gets to the top end a lot faster than thick oil.
I've always thought the bypass only kicked in when the filter was plugging. Because of not changing as often as you should. It makes no sense to me that your filter is only active at idle. If I knew that, I would find a filter that had no bypass until the filter was plugged. Motors wear and very small metal particles end up in the oil and need to be filtered out. Other wise the motor will not last very long. So what I am hearing can not be true. If it was, most mechanics would know about it and better oil filter systems would be mainstream. If I had to run more filters to get the flow I need without any bypass, I would. Motors are not cheap. Especially when you figure in the labor to remove and replace back into car. At idle, the crank is spinning a lot slower and not as likely to have the turbulance to lift heavy debris from the bottom of pan as say, a motor spinning at 3 to 7k rpms. If what Tony is saying is true, then having a filter that filters all the oil that passes through the can, motors would last millions of miles. So no, I think they are filtering until they start getting clogged.
This is why I use a Mann oem filter on my German car. It has a 38psi bypass. I used a k&n a few times early on and the oil got dirty quick.
I have a SBC 385 stroker (4.04"x3.75") in my Camaro. I use a K&N HP-6002 2-quart oil filter. It doesn't have a bypass or the anti-drain back valves. I also blocked the factory oil bypass in the block. All the oil goes through the filter. I use Amsoil Z-Rod 10W-30 oil. I only drive it in the warmer months.
Back in the daycare had no filters. Grandpa changed oil evey 1000- 1500 miles
LOL, I see vids comparing filters all the time and they never really mention the pressure bypass! This definitely needed to be said UT! Learned this during Mercruiser training many years ago. Good stuff UT! KUDOS!!!
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That bypass valve is the reason I laugh at people who insist on pre-filling their oil filters through the small holes rather than the big one in the middle. As soon as they start the engine that oil goes through the bypass valve lol.