How to Test For a Bad Brake Booster / Brake Booster Testing
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- Опубликовано: 29 сен 2024
- In this video show how I test for a bad brake booster and check valve. Testing a brake booster for leaks is pretty easy and doesn't require a bunch of tools. The exact vehicle in this video is a 2002 Toyota Tacoma pickup truck. Enjoy!
P0171 diagnosis on this truck: • P0171 Trouble Code: Sy...
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Tools used:
OTC 5213 pressure/vacuum gauge: amzn.to/2GZJgVM
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Brilliant! Greetings from rainy England. I was stuck trying to fix my brakes on an Audi A6, which would work fine but occasionally suddenly fail. This was not improving marital harmony. I watched your video, where you explain how the servo assist system works and how to test for faults. Armed with this knowledge, I strode manfully to the carpark, where I had abandoned the dangerous car. Problem solved! - the vacuum feed pipe was not tight in the rubber tube that goes through the bulkhead to the brake servo. I wrapped ptfe tape round the serrated pipe end to make a tight seal and added a tie wrap round the rubber pipe to stop it coming off. The brakes work much better now. It was knowing how it worked that enabled me to diagnose and then to fix the fault: thanks for sharing the knowledge.
Thank you for sharing this information with us 🇺🇸
6:07 mine is firm with the car off, turn the car on drops almost all the way to the firewall
You for making this video. Trying to self diagnose after I was given a questionable diagnosis
Thank you
It explains EVERY aspect of testing the brake booster. Thank you,
Thanks 👍!
I know this is an old video but I just want to say dude you just help me out a lot this video will help people for years to come
Glad it helped, thanks for the comment!
It just helped me.
Been driving myself crazy trying to figure out why my van only runs right when the booster vacuum hose is disconnected.
I have to pass a knowledge exam soon to change class as a mechanic and your video are very helpful, you are a great teacher.
I appreciate the comment, thanks!
Hi
I am impressed by your football acheivements. Congratulations. You were a part of an amazing team and you are an amazing man to help people with your education. Thank you for this awesomely articulated video. Your shared education on this matter is a big help to me. I hope more people that make videos share their sports acheivements at the beginning like you did. Go Laney!
yes this help it was master cylinder and now i learned how to appreciate a power booster
Couldn’t have done it better myself excellent video sir! Every possible easy way to check the booster/vacuum/master cylinder system. Thank you
Just picked up a 2003 F150, will definitely be using these methods to see what is going on. Upon the first press of the brake pedal, the pedal goes down quite far, then if you pump the brakes the resistance goes up, and the pedal does not have to be depressed as far. So it is as if you have to build up the pressure. The pedal is very easy to press, so I am suspecting the master cylinder. It feels as if the booster is doing its job.
This helped me get through some daig on my first day at a new shop thank you
Good job Sir it's a perfect example to Check Boosters .I do it as you do
👍
This was helpful, we inherited my sons 2003 expedition, its braking is a lot harder than i remember it being, and certainly harder than my 2006 f250. i was thinking brake booster, but ill check vacuum, line and check valve first. The beginning of your video reminded me of Uncle Rico in Napoleon Dynamite thinking about the glory days of him being a QB, made me laugh...
lol, thanks for the comment!
Thank you so much for being so clear
Excellent advice. Helped me diagnose my booster. Thanks!!
WOW!! Learned more about brakes in this 10 minute video than in the last ten years! You are the brake GOAT!
MANY THANKS!!
vacuum hose sensor was broken at the stem! Thank you!
I Replaced brake booster, master cylinder, calipers and brake hoses. My brake pedal sinks hard. As if nothing there. So check for a vacuum leak. Got it. On my 89' sububran.
I'm a very mechanical guy but I'm stumped on this one. I have a 2008 Escalade. Brakes were perfect, I put on all new rotors, calipers and pads about a year ago and brakes have been super smooth and worked perfectly. But last week I had to really stand on the brake pedal to keep from hitting a car that pulled out in front of me. I wasn't going fast, maybe 10 MPH or less. But since then the brakes want to stay engaged under certain conditions. If I come to a complete stop, the brakes release fine. But if I lightly press the brakes like to slow for a turn or to go over a speed hump the brakes lock. They don't "lock" as I can't move the truck, but when I remove my foot the truck continues to slow down and will come to a stop on it's own. A quick firm press on the pedal and it releases but driving is a pain. The pedal seems to not be retracting all the way up in these conditions. I can put my foot under the pedal and pull up to release it. And of course when trying to drive the truck with the brakes lightly engaged I get all the ABS, traction control warning lights. Any thoughts?
Great demonstrations of the diagnostic procedures,thanks for the video....
Thanks for the comment!
My good sir through you I have found a bad booster and master cylinder at the same time... Sometimes lean codes sometimes evap codes and even transmission and fuel issues... These cars with all these sensors it's like a chicken with no head
Thanks to you I fix my brake problem in under two minutes… Right on!…
👍
very informative. thanks for sharing!
Thank you for the comment!
amazing movie so informative and so concise thanks again I am going to apply to my car :)
Mine was just professionally replaced now it whines any ideas?
When you're at wide open throttle, you're typically not on the brakes so it doesn't matter if the valve is even there. As soon as you come off the throttle, engine vacuum comes right back and most people won't even notice an issue. Just like my customer that was in for an oil leak and death wobble. No mention of the pedal being hard while on the throttle since most people aren't on the throttle and brake at the same time. The only thing that check valve is for is to maintain vacuum in the event of engine failure and you get at least 2 assisted brake applications.
MS Juco is where its at Itawamba Indian 93-94!! :)
Omg! Thanks for the help, i did all the steps . Everything is good. But still happens to me while i was driving on high speed , my brake pedal gets hard when im travelling on high speed around 150km/h. It just stucks and hard to depressed.
Well from what he says around the 1:30 mark, if the pedal is sucking all the air the brake booster might not be getting enough vacuum since all air is going into engine. Might be wrong but could make sense in your situation.
Good, thorough explanations
is was amazing and very helpfull👍
Sorry to bother you, but I have 1970 lincoln mark iii when the car is off, the brake pedal is very hard. But when I turn the car on the pedal go all the way down.???
Any idea what can be!!
My breaks are sticking for 6 seconds before they release, so I had a new vacuum pump fitted. Pipe and non return valve are ok. Any ideas ? do you think maybe the servo is not working properly. breaks are still sticking. great video
Could be a bad fixable brake line especially if it's only one wheel: some times the brake line brakes down internally causing a check valve condition in the brake house where the caliper isn't able to release right away after taking one's foot off brake pedal.
Great video !!
Good idea guys.
what I did not follow is the direction of vacuum flow through check valve. You said that you shoukd be able to suck & not blow. The direction the valve appears mounted seems like built up vacuum would travel the same direction as your sucking demonstration.
Valve needs to allow vacuum (from engine) to be pulled from booster but as soon as vacuum is cut (engine turned off or high RPM) then the valve needs to close and hold the vacuum inside booster and not let booster equalize. Not the easiest thing to explain.
What can cause the pedal to sink a bit when the AC compressor cycles on? I am thinking vacuum lose?
If the master cylinder is leaking then u should see brake fluid leaking
Great info sir, I think I m facing problem by booster issue in my Toyota etios from 5-7 months. I was worried about head problem, but now I m sure that it's booster issue. It hard my wheels, vaccume not working, no leakage in booster. It works little properly on highway. But hard wheel in city. What problem it is, and can it repairable or replace with new one
Weird question. Can a brake booster be bad, causing a vacuum leak, but still work well enough for power brake assist?
Yes, that is what was happening to the vehicle in this video.
I understand it and now know how to test it..Thanks very much for that.
But one question regarding valve test..You said air should come back up from bottom of value (The part used to be inside the booster) and it will hard to blow from top down makes confused..because one way check valves work to block air coming out from the booster..Thanks
When the engine is running, the pressure from the engine opens the check valve as the engine vacuums the booster (vacuum test) like you saw on the video and when you shutdown the engine, the valve closes maintaining the pressure difference in the booster within a given time frame. My thoughts though!
Any idea if a cracked manifold would reduce vacuum?
How high is the vacuum? Can I hook it up to a hose and use it outside to do some moulding?
What an Excelente Video, Thank You!
Thanks for the comment!
Shad shoe my friend.Knew the tests,but was doing them out off sequence.
The only test it didn’t pass was the 3 brake assist after the engine is off? Would that fail the booster?
Exellent😊
Thanks!
Well done 🤝💪
How much vacuum is needed for a booster to work properly? At what point do I need a vacuum canister for a high lift camshaft?
What if the brake pedal goes to floor and regardless of which way I do it
Great info..thanks
6:08 dont you mean it wont sink that much because of the bad booster? Cause if the booster is leaking there is not that much assist, so the pedal will be stiffer when you start the car right?
Great video.
I have a 03 Silverado with a 5.3. I hear a whistling noise that’s kind of quiet that from inside the cab it sounds like it’s right in front of me from the engine. I’ve been told it’s a possible vacuum leak. I’ve looked and looked and can’t find anything. I’ve even sprayed almost an entire can of carb cleaner around trying to locate it and can’t find anything. Any advice? Thanks
I went to Laney too. small world
👍
Thanks
👍
hmm went to a very reputable mechanic for my vw cc, they said I had a bad brake booster. I did this test and passed it. IS there anyway it could still be a bad booster or would it be master cylinder?
Thanks sir
so ... mine acts like i have a leak, it lets me push it down slowly everytime non stop with the car off... but i am not losing any fluid, how would i find a leak? or can this stil be booster?
HI,
I have a Mazda 5 2010.
The breaks works fine in general driving with 2000 or more rmp.but with slow drving in town etc rmp around 1000 the breakpadle get 'hard' after pushing 1 or 2 times.
I have changed the vacumehose pack with the valve included...
What can be the course ?
Hope you can reply me..😊🇳🇴
I’ve been endlessly chasing a rough idle and noticed that if I pump my brakes multiple times at idle me AFR and fuel trims go lean and the rough idle is more noticeable. However, I cannot find any leaks in the booster vacuum line and the system seems to hold vacuum perfectly. I’m losing my mind on this one
Mine is doing the same thing,did you ever find out what caused yours??
@@katbirddogg8184turns out it's normal for fuel trims to go lean when continuously pumping the brakes. as for my rough idle I just ignore it now
if I get an answer I'll give you a thumbs up
Question, I'm running a 2003 350Z for road track use and after a couple laps the power brakes stop working and the pedal goes hard so no power assist at all but breaks still work. When I pulled the vacuum line the check if valve was holding air, nice loud pop of air when I disconnected the line, so would this be a bad power booster?
Does this apply to 2011 Prius?
My 01 accord idle drops to 5-600rpm when pressing brake in Park or completely stalls when coming to full stop when driving. Any thoughts? besides that car is fine.
Does it surge as in the idle bounce around I’m a Honda guy I know a lot lol check out my vids
Great video, thanks
👍
Detailed and very helpful. Thank you.
Glad it was helpful, thanks for watching!
Thank you for your vídeos. My Nissan Xterra 2003 dies out after presing the break and turnin at the same time Chile driving. This happen right after a booster repair job. No body has been able to fix it for me. All marked sensors have been changed and nothing. Have any advice? Thank you.
If it happened immediately after the brake booster work was done, then I would double check all work, especially all hoses and connectors that could have been disconnected or damaged. A test that can be done to eliminate a bad booster is to seal off brake booster vacuum hose and see if the stalling problem goes away (I would not drive the vehicle around this way, this would only be for testing). If the vacuum hose is not connected properly, or is damaged, or is pulling in pirate (unmetered) air through a bad brake booster, then that can cause driveability issues.
Great video. I got new rotors and a new master cylinder (pedal was sinking to the bottom) and the brakes were working great for over a month. Then one day,the pedal would get stiff while driving and I noticed the brakes engaging without me pressing the pedal.
The check valve is working correctly and after I reconnected the vacuum home,it was working normally again. What could be the issue?
Great question! I have the same issue on my old Tahoe. After watching this video I'm planing to replace the booster.
@@4mbrad642 I replaced the brake booster and it fixed the issue!
Thanks for following up with the solution. I've had the same issues as you and many others. Weird stuff. But no one ever comes back to share what they replaced/repaired and ifnitnworked or not... for that, sir, i say, Thankee.@ShinkuGouki
My brake booster has a nasty hiss each time I shut off the engine and there's a P0171 lean condition . Does that look like a decent sign that my brake booster is failing? I've done a smoke test from both the intake manifold and the air intake hose and did not find any leaks
Did you figure out this problem im haveing the exact same issue from the hiss noise and the check engine light with the same code p0171 any help on this matter thank you
Would a internal leak on the booster cause erratic acceleration when your braking/slowing down to a stop?
I guess it depends on system design, but in general it would most likely cause a harder/stiffer brake pedal, which would require more effort to stop.
Very well explained. Appreciate the accurate information! I Wish school teachers knew/explained their curriculum this well.
Thank you, I appreciate the comment!
They do! That's why our kids are becoming commies
@@capitanvonchickenpants8492 I see what ya did there lol. agree. also doesnt help they encourage little boys to think they're girls.
@@darkskinwhite look up yuri Bezmenov
Fantastic video - thank you!
Thanks!
Great video.
Thank you!
I love the way you explained everything. You did this better than most other sites on RUclips. THANK YOU!
I appreciate the comment, thanks!
Congratulations to Polk High. I played with Al Bundy. 😂
lol
Al Bundy is legendary. Did you know he scored 4 touchdowns in 1 game? Four!!!
Nah. Al Bundy was a running back. This guy is Uncle Rico. He could've gone to state.
Just helped me diagnose a the problem. Saved me from buying parts I didn’t need and some frustration. Many thanks!
Glad it helped, thanks for the comment!
BY FAR, the best video on the subject that I have found. Sincere thanks!
Serge in Chicago.
Imma go see!
2012 tahoe 5.3 the check valve is built-in the sensor, and failed the test (I could inhale and exhale freely). Replaced the sensor and the "Service brakes soon" message is gone. Thanks!!
I had recently replaced a fitting that fixed a vacuum issue (fitting on manifold) that had turned on check engine light. Parts store clerk said it was for brakes and whether I was having issues. We weren't, but the check engine light was on for vacuum issue. Light went away when fitting was replaced, but came back on several days later (I did not reset light, it just turned off when fitting replaced). Diagnostic showed no errors, but history showed brake issue. It's clear now. Video helped explain how vacuum loss could cause the "brake" check engine light issue. Thanks.
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10/10 mate. Straight to the point, great, simple, yet vital information other channels aren't addressing.
I appreciate the comment, thank you!
Thanks Big Dog! Very detailed yet easy to understand, excellent job!
What if the brakes don't push back when the car is turned off. When it turn the car on, there is a dull clicking sound coming from behind the dash.
Another sign you have a bad booster is that it’s a Toyota. I’m about to replace my third one on two different Land Cruisers
Wow, to the point and very professional, I was able to check some things while actually watching this video…great content I will be following you from now on!!!
Thanks and welcome!
Also if STFT continues to climb while applying pressure to brake pedal. The booster has a vacuum leak.
I am having an issue with my Honda Civic 2004 ES
On smooth surface my brakes work perfectly, but as soon as I hit an uneven surface while braking, the brake's pedal gets harder, starts blocking and shaking. I am still wondering what is the issue with that. Can I get an advice about the issue please?
Great guy very good teacher helped a lot Thank-you.
I have bled my brakes 3 times for squishy pedal syndrome. The third time I bled my brakes I used a pressure bleeder and my brakes were great and fine for a couple months until today when the squishy pedal came back. I didn't think it was the master cylinder because it would get better and not come back after bleeding the brakes. Each time it would come back, it would seemingly happen over night.
I did the last test that you described to do that tests your master cylinder, with the engine off. I pumped a bunch of times(6 or 7) to get rid of vacuum in the brake booster, then I held the brake for 15 seconds. My brake pedal held firm and didn't sink, it did do a really weird thing though after 15 seconds of having this very very slow pulsing that would push my foot back very very slightly almost not noticeable. It would push back for maybe 5 seconds in a gradient pulse, and then go back that same amount. Again, my engine was off, and the distance it pushed back was so so so small so I would think it wouldn't be an issue, but I also never expected it to have a gradually sweeping pulse pushing my foot back when the engine was off.
I would think it is air in my system, or a leak? What do you think? If anyone else has any ideas or experience with this, I would really appreciate any expertise! Really wanting my brake gremlins to be stomped out after maybe 4-5 months of this now.
Did you figure it out?
Would a bad brake booster cause the vehicle to jump 500 RPMs when the brake is applied or does that sound more like a vacuum failure?
Dave, Excellent video. I have few questions may be helpful to other viewers. May be my questions are silly but will help a lot to understand and correlate lot others
1) At 4.45 you said Air is escaping, but I think it is vacuum because if vacuum is not there in booster it push the pedal up.
2) At 5.00 you said, for good brake booster we should be able to push and hold the pedal for first 30 seconds, so why is that it wont hold after 30 seconds, does that mean after 30 seconds vacuum will disappear if so how will it deplete, again this question is for good brake booster not for bad. I am trying to understand why it can hold only for 30 seconds and how is vacuum depleted. I dont think vaccum in booster will go past check valve so my theory is it should hold all the time, unless there is a depletion somewhere.
3) AT 6:07 the failed one in this case is pushed farther than it is supposed to be, what I didn't understand is failed one is hard to press, but in this test it goes farther i didn't understand the theory.
4) at 8.33, you said we need to have 3 brake assist without vacuum. I assume you are using existing vacuum in booster, is that right. because without vacum we may not get that 3 brake assist..
Sorry too many questions.
1. Yes it is losing the air that is under vacuum.
2. The 30 seconds is just a general guideline that can be used as a test, these system are not designed to be 100% air tight over long periods
3. It is not pushed farther down, it is pushed down to normal position. The pedal started up higher (and traveled further) because there was no vacuum stored in the booster to assist at the start, but as soon as engine turned on then vacuum started to assist and the pedal went down to normal position. This booster was bad but it was able to hold enough vacuum to assist as long as the engine was on (but it made the truck run severely lean, as shown in my P0171 video).
4. Yes the booster should be able to hold enough vacuum inside to assist for 3 presses of the brake pedal.
how did you know when the master cylinder failure or the booster?
8:53 the last test he explains what would indicate a leak in the master cylinder internal seals
Also the break booster will cause a lean condition on your fuel trims.... On both bank's...
Great set of tests. My old truck must have a bad booster, when i press hard enough i hear it hissing and the engine RPM’s drops down. Lol 😂
This video shows how a bad brake booster can cause a check engine light ruclips.net/video/SugtR4KMIDU/видео.html
Everytime I hope my brake booster hose to the plenum it stalls out but when I understand hook it it starts up
I've changed the whole driver side for my brakes on my Honda pilot it's the only side not releasing why is dat
@@-g.k.4389 +qq+
can you just remove the check valve, or woul the pressure be to high and cause problems ?
I think everybody else has already said it: you do a fantastic job explaining the how and why of each simple test. Thank you!
Thanks 👍!
LEGEND HAS IT HE ONCE SCORED 4 TOUCH DOWNS IN 1 GAME #THEREALLIFEALBUNDY
👍 lol
Dave, excellent video. I noticed that Big Dog 50001 coffee mug in the beginning. If you have any extras I would love to support your channel. Your videos are excellent. Thanks for your time and effort.👍👍👍
Thanks Arthur, I appreciate the support! I will let you know if I get extras.
You do love your coffee mugs Arthur! haha!
Mike what ever gets us thru our day. You know what I mean. Take care bud 👍
@@arthurfricchione8119 yes sir! And I appreciate it!
Great job on explaining simply and covering everything, the shops hate you but we DIY people are very grateful! I'm sure you've helped atleast 100k of the 5 million that watched this if not more! God bless brother 😇
My brakes become stiff by themselves with the engine not running. At the garage they said it was normal. I told them it was normal if you press the brakes 2-3 times, but not by it self. Anyway they said the important is that it works while running, and they never saw this problem ever. Do you know what the problem can be?
I enjoyed this video very informative. Would this test work on a 2017 Mitsubishi outlander?
The brake pedal is not airy when the vehicle is at rest but super spongy when it's running. Despite almost sinking all the way to the bottom, it actually works super well and the grip sets in just right in the middle. It seems to me that this does not match with the description of this video. I wonder if it is the master cylinder issue, or something else, but what can that be?
What if it's leaking air between booster and master cylinder, what would be that problem, thank you
When I connect my vaccum line from the brake booster car starts and quickly stalls out. But when it is not connected the car starts up. I did accidentally crack the master cynlinder resivoir
my 72 chevelle starts and stalls randomly aswell so every timer before i start it i pump the gas about 3 times and it it usually starts fine
Replace