If you found this video helpful, please consider supporting the channel! Check the links in the description. Don't have any money to spare? Just shopping on Amazon through my amazon store link helps, even if you end up buying something not listed in my store. Doesn't cost you a penny! Marvel Mystery Oil experiment is underway. We will see results soon, and also hopefully get to do a full rebuild on this engine. Please comment if you have information on parts for this powerhead! Have a great weekend everybody!
Johnson TN-26 Compression When I was a Second Lieutenant pilot trainee getting ready for my first jet solo, I pointed at an object with nuts that were safety wired into place and asked the grizzled old crew who was helping me strap in, “What’s that?” He said, “Works fine, lasts a long time, don’t f*** with it.” Good advice with all things. Doing your compression test, you had about 62 PSI on each cylinder. According to The Classic Outboard Motor Handbook (pp. 44-45), anything above 50 PSI is acceptable on a seventy-year-old Johnson. Also, your compression readings on each cylinder were well within ten percent of each other, and there was little variation with or without a spark plug in the untested cylinder. It’s very unlikely that you have a blown head gasket with such readings. One thing you could check without violating the crew chief’s advice is to check crankcase compression. First, check that the screws designed to hold the crankcase together haven’t vibrated loose. If they have, you might have found your problem. If the screws are tight, remove the carburetor one more time. Place a tissue across the intake manifold and turn the motor over. If the tissue wiggles, there’s at least some crankcase compression. (Because of the crazy low speed needle operation on this motor, you might start by doing the same thing with the rotary valve intake.) If there’s no apparent suction in either place, or only a little, you might need a new crankcase gasket (ibid p. 109). With your skills, I know you can make a crankcase gasket - head gasket, not so much. I suggest following the crew chief’s advice, and just enjoy burning some 16:1 fuel and oil mixture through the old boy once or twice a year. That’s about all a seventy-year-old Johnson should be expected to do, right?
You ough to teach shop ... I've been wanting to understand this for years and like you I enjoy learning why something works the way it does Thanks John for explaining the way this works😊
man the owner's manual back then was a whole another level thing. Imagine getting a car or something today and getting a full breakdown on how the engine works so you could fix it whenever it breaks / modify it to suit your needs better
Most locomotive engines are 2 stroke diesels that operate in similar fashion. The crank doesn’t get fuel, but there is still a clever arrangement to get it all done in 2 strokes. As you were saying, it’s a great way to get good power to weight ratio, but on a locomotive you want a lot of weight. But running the engine at a lower rpm still gives good horsepower on a 2 stroke, so that is very desirable on a loco for longevity. Max RPM for an EMD 710 locomotive engine is under 1000 rpm. At max RPM a 16 cylinder makes 4500 hp, which gets converted to 3.1 megawatts in the main generator on modern locos. So… 2 cycle for a loco, big horse power, low rpms.
All Johnson jokes a side though a bit of laughter sneaks out when you crack the joke.. Really enjoyed the explanation’s that you share in detail. Really helps understand functionality with the proven comparison your showing. I truly hope you find another outboard to tinker on, I personally have learned alot from your “Johnson” and really any video you do you give all possibilities with details. The world is a smarter place having this channel available! THANK YOU.
Hello from Finland! I have enjoyed watching this saga. Old outboards are my hobby, specially been restoring Britsh Seagulls and small OMC engines from -70's.
Ever see or find any Archimedes Penta opposed twins over there? Only a few over here in the states. I worked for Penta for a number of years and would love to find one someday.
OMC'S Are awesome, do you have the book "Evenrude Johnson and the legend of OMC"? They used to have a large boat here in Milwaukee with every outboard on its stern.
Dude, you just have to accept that when your Johnson gets old it simply doesn't perform like it did when it was new, no matter how much magic lube you use.
I’ve worked on outboards for 25 years and I’ll tell you that most smaller motors(25hp or less) with head gasket failure was between the cylinders, it’s usually the narrower part of the gasket. I believe your compression is perfectly fine. Compression on a two stroke rises with rpm, also the smaller volume combustion chamber doesn’t require as much compression as a larger one due to using less fuel/air mix. Just my 2 cents.
This channel is growing rather quickly. I’ve been around watching for a while now and I’m excited to finally see the recognition here on RUclips that you deserve!
Let’s hope at least try head gasket and rings if possible. The reed valve parts sometimes go bad on two stroke that sit a long time. The engine sounds pretty good now. Great project
Hopefully, if anything is bad with the Reed valve, its just something a good cleaning and polishing of the surfaces will fix. Hopefully it is just a bad head gasket and not a whole can of worms. I spent last week tearing apart the rear end on the work truck because it needed a axle seal. That turned into almost having to replace the whole rear end. We're kind of Lucky it didn't just explode on us driving around in the hay field checking on the cows one day.
Your explanation of the two cycle engine is right on point but there is another factor which improves performance. When an expansion chamber is attached to the exhaust port and tuned properly, it causes an impulse to occur just before the exhaust port os closed which forces any fuel air mixture which may have escaped back into the cylinder. It can in most cases improve the compression as well. Or something to that effect. It is cool to hear a motor tuned properly “get up on the pipe” and go like a scalded dog!
I had a motorized bike, nd I put an expansion chamber on it. When it came "on the pipe" it was almost scary. Bicycle was NOT built for that much power! I've been playing with 2 strokes for about 1/2 my life. Yamaha had a wicked fast street bike. RD400. Wish I still had one. steve
Thank you for schooling me. I now understand the differences. You did a great job explaining everything. Thank you. I own a 115 hp Evinrude/Johnson outboard. I am not sure if it's a 2 stroke or 4. I know now what to look for. Thank you for your help!
Keep Going. I had an Evinrude blow head gasket between cylinders, it ran poorly, spitting raw fuel out of exhaust. after a few seconds, motor quit and would beardly start, very little power, then quit after 5 seconds.
Small cylinders always show lower compression values than larger cylinders. The first thing to do is check what compression your gauge shows on a healthy running small engine maybe something like a chainsaw or brush cutter. If the values are also low then its the way the gauge works. I have had many small engine newly rebuilt show 80psi on my gauge but on my car hit 160psi with 250 000 miles. The fact both cylinders indicate very similar nimbers leads me to believe the rings are still good
I.E......"relative" vs "absolute" numbers. Comparing the pressure of one cylinder against the other, shows the relative relationship. But in this case, the concern is with the low absolute values. It's easy enough to test the gauge with an air compressor, to see if the absolute values it is providing are accurate.
@@ls2005019227 your theory is correct but in practice. All small cylinders show lower compression number than larger cylinders simply because of the volume of air being forced into the same space and that is compounded by the fact this is a 2 stroke with low compression ratios usually around 7:1
Was watching BigStack videos and found yours by accident. Browse through a few videos and love what u do. Earned both respect and subscription. Keep going my friend
I like your Johnson...series. I thought the series was over. I'm so excited that it wasn't quite. I wish I could help with my comments. But hopefully you will be happy enough knowing that I ALWAYS learn something when you make a video.
The hose length on the compression gauge will not affect the final compression reading, but it will take a lot more cranks to get to the final reading.
A leak down tester is a better tool for checking engines, I've made my own and its a very handy tool. uses compressed air and any leaks are easy to find. great video's!
Wayne Pulley, formerly of Pulley's Marine on Gwynn's Island in Mathews County. He was a Johnson dealer for years and years. I just saw him earlier this month. He's long retired, but he can probably tell you exactly where to source all that stuff. Obviously I'm not going to post his number and whatnot on here, but he shouldn't be tough to find. Good luck. Awesome project. 👍👍👍
Can't wait to see the upcoming episodes! I'm with you and most of us viewers....leave her looking as is and try to do what you can. Ultimately she runs!
I had a similar situation with a 1959 Evinrude Fisherman Golden Jubilee 5.5HP Engine that somebody gave me. It had been sitting in a barn for 40+ years and didn’t run. It had low compression, and decided to take the head off. I found out that the part of the head gasket in between both cylinders was burned, which in turn caused the low compression. I replaced the head gasket, sanded down the aluminum head with 2000 grit sandpaper to make sure the head was evenly flat, then put the head back on, torqued it down to the proper specs, and voila, compression was back. I got the engine up and running again, and now I was able to move forward with cleaning the carburetor, and replace the water pump. It’s a great runner again rather than a static display.
Just like any 2 stroke, pull off the muffler, turn over the engine by hand and look at the pistons and rings, if there are visible scoring marks or damage to the piston then you have your answer. If it looks good (which is subjective but I'm sure you're snart enough to make a judgement) then leave it alone. Look at the piston, is it all shiny (worn), scratched up (damaged) or are there some machining marks still visible (perfectly fine). Also you may be able to measure the ring thickness which combined with taking the head off and measuring the bore size will help finding replacement parts. Like i said previously, try run it with the best 2 stroke oil you can buy which is synthetic motorcycle oil (for water cooled engine) Motul 800 or Maxima or Amsoil etc. They have a much higher film strength which helps the oil stick around the rings and gives better sealing/compression, it works. Not sure this engine will have reed valves, could just be Piston Ported?
My guess for checking compression when cold is so that the baseline is comparable to the numbers the manufacturer setup if indeed they created those numbers for a cold engine.
Hello from England Thinking a simple hone buster used very sparingly will really make a difference. Run some seafoam through with the fuel oil mix it really helps loosen stuck rings. lastly any 2 stroke needs to be used hard. An Italian tune up makes the world of difference
10:18ish if the throttle is closed wouldn't that create a vacuum in the crankcase restricting the amount of incoming fuel /air interning the crankcase ? I think it would !
I would say hold on a bit! Fact is, compression gauges will very, but the compression of each is comfortable, and you have it running strong. You are right about going in deep can become a parts nightmare, and you know the old saying..."if it ain't broke, don't fix it!" It is pumping great, you've got that, starts easily (every old engine has it's own personality). I know you mentioned it in one of the vids but missed it. Not so worried about putting mystery oil or such in except when first messing about with the engine after sitting, but don't skimp on the oil mix. Lots of younger mechanics say you can use a thinner mix because newer oil is so much better... Bah! No! Use what is recommended for that engine, as it probably shows on the tank instructions if they still are there. It is not about the new oil, it is about the size and type of bearings. Outboards are under constant load when they are pushing. New oils may be less smoky. Many of the commercial river fishers used to use straight 30Wgt way back in the sixties. These guys used to smoke pretty well. Who doesn't love the smell of two stroke in the morning! :) I do agree with the keep it original as well. That is a pretty engine as it sits. Hell, I'm 69 and I know a face lift won't make me run better! Worked almost exclusively on fifties/sixties engines for a small shop in Delaware way back, and with the USAF MWR when I was in Interlick Turkey where we kept a small fleet of old rental boats alive. Been messing about with boats ever since, albeit just enough to keep mine in the water. So run the little guy a good deal and see how it settles down. Protect it in the winter, keep any 10% ethanol fuel out of it or empty the system after each weekend. Very good vids!
I love the way you presented all the in's and outs. Discussed all the options. Marvel Mystery Oil we used that stuff everywhere, including on cuts as a disinfectant. I wonder if it would help the Arthritis in my right hand? ✌🤟🖖
Great explanation of a simple two stroke. Wait until you get to work with tuned exhaust with a two stroke. Expansion chambers, properly designed can use the exhaust pressure wave created by the shape and length of the exhaust to actually have a supercharging effect at a very narrow range of rpm at the high end. During the overlap when both the exhaust port and transfer port being open, some fresh charge follows the exhaust out, but the bounce of the exhaust pulse will push that charge back into the cylinder in affect pressurizing the charge because the transfer port closes first. On the Kawasaki H2 Triple with racing chambers, going past 5000 rpm felt like you flipped a light switch, and it was hang on for dear life!
With a 4 stroke, shooting a squirt or two of oil into the cylinder before a second test will help determine rings or valve leakage. Could this work to help diagnose head gasket or bad rings in a two stroke???
You'd have to match the rpm at pull speed because that's all the more rpm that is available on initial startup. So if it runs at pull start rpm then it's obviously adequate to generate enough compression to run otherwise it would never start. Then once you've established compression at pull start rpm then you've got a base line to measure the increase at throttle rpm. So you'd have to put a timing light that measures rpm on a dead pull then measure from that point to whatever the factory specs claim rpm is at full throttle. Two strokes are a pain in the ass to diagnose but it's honestly probably your red valves from sitting so long they get rusty along the outer edges closest to the ports and then as you run it the heat burns off the thinner compromised material and steadily reduces efficiency until it just won't hold enough viable compression to start and run.
You can sometimes get low compression and yeah the components aren’t warm but the piston rings have lost the spring in them from possibly being overheated or just age it is possible to put some spring back into the ring but it is a last resort if you can’t get new rings I’ve done it in the past by stretching the rings over an old piston and blow lamping The ring until it is glowing cherry red I’m not sure whether I should have quenched the range at this point I didn’t but I got reasonable result but I would recommend this is a last resort cheers Derek
On two strokes, there is a bit of a dynamic effect to the intake portion of the cycle. It's not easily explained in a comment, but there is a bit of a supercharging effect happening in the crankcase, as well as a scavenging effect with the exhaust leaving(Though not nearly as much when just turning it over as opposed to it actually running), so compression is more RPM dependent than normal even when everything is in good shape. Not to mention there's always some degree of dynamic compression that comes into play due to blow-by. That's not to say that there's no issue with the head gasket in your case, just pointing that out. But none of it is really a factor you should worry about much. Your tests are perfectly fine. Fortunately, it's a two-stroke, so it's really easy to get in there to see what's going on. Unfortunately, finding a replacement head gasket may be significantly less easy. As for Marvel Mystery oil, great stuff, I absolutely love it. It's awesome for breaking free a seized up cylinder in my experience. But it won't do squat for lost compression, nor do I see how it possibly could except for one oddball possibility that wouldn't apply in your case as you've already had it running for some time. It really is a cool little motor. As a mechanic by trade, it makes me all warm and fuzzy inside watching you keep her ticking. Lol.
I've seen some videos explaining how a two stroke engine works and particularly find this explanation the easiest to understand, even thoug my mother language is spanish.
Great work in that old Outboard. If cylinder bores are chrome plated and worn too much that's going to be a challenge but not impossible maybe bore out and resleeve if block is thick enough or have them replated. Pistons rings can be bought according to size needed. Bearings or bushing will just need to be machined out to fit. I would try Amsoil and see what happens. Good luck,waiting on next installment.
Compression check: If you are relying on air to enter the cylinder via exhaust port (throttle closed) would muck, carbon chunks or rust not potenbe drawn back into the cylinder, especially if the engine has been standing for example..just a thought.
Don't tear the powerhead apart yet. I found my Johnson Service Manual (10th edition), and my TN-26 Owner's Manual. I think your Johnson might not be too far from normal. (Regarding compression, at least :) I gave myself a brain blister trying to calculate piston displacement, compression ratios, and PSI tonight. I'll try again in the AM when that Rusty Nail has worn off.
I think that it's important to point out that crank case supercharged, flapper valve 2 stroke engines are thought of as representative of the 2 stroke cycle in the US, but they are actually a corner case of 2 stroke cycle motors overall. It is possible to use the engine layout shown above to make an extremely simple/cheap but also extremely dirty 2 cycle engine, which despite requiring some form of intake charging is still simpler than a 4 stroke due to the lack of valves. That is by no means the only 2 stroke layout: the biggest, most efficient engines on earth are all 2 stroke, and the oil path is indistinguishable from a 4 stroke. 2 stroke engines, because they lack an intake stroke, are necessarily the flithy, crank-case charged "Weedeater engines" that we are familiar with IF they lack some other kind of intake charging and direct fuel injection. In the 1950s-2000s, when big, normally-aspirated 4 strokes were the norm, the only clean 2 strokes were huge engines like the Detroit -71 series. However, any engine using positive pressure charging and direct injection has met the difficult threshold for making a clean 2-stroke, and those features are increasingly common now. For instance, the entire Ford Ecoboost line already has all of the expensive parts of a 2 stroke (direct injection and turbochargers), such that converting the design to 2 stroke would actually involve making it simpler/cheaper to build. Thus, the idea that a 2 stroke engine can only be what we have seen thus far is deeply misleading. For a design with a presence on youtube, you might check out Achates Power, which is a modern variation of the old Junkers Jumo/Fairbanks Morse 38 8-1/8. More conventional SCCI 2 strokes whose development was sponsored by the SAE are also getting similar thermal efficiency, up to 55%, with soot/NOx emissions which are significantly better than current production 4 strokes. This is a really cool and old 2 stroke radial diesel 2 cycle: ruclips.net/video/ZMVHflfCdmg/видео.html . It's pretty easy to find videos of Detroit -71 series motors, and those are all 2 stroke diesels as well.
i am loving this series, i have a '39 "HS 39 Johnson" and am trying to resurrect (her) but i fear the quick action magneto is faulty. i also have a canadian OK15 from the 40's suffering a no spark syndrome. your series has given me hope
If a motor has sat for a lengthy period without running the oil in the bore can have dried/evaporated or seeped away affecting a compression test. Otherwise, unless doing a wet test (adding oil to the cylinder after a dry test to potentially indicate where a known loss of compression is occurring ), the vast majority of the compression tests I've performed have shown little difference between warm and cold readings on a recently operated engine.
a quick way to check the rings would be to push a bit of engine oil into plug hole. if the bores/rings are bad you will see a substantial increase in compression
I run a 1999 Evinrude Johnson Oceanpro 200 two-stroke on my dual console boat. The starter spins the rotating assembly about as fast as your drill on high. Not sure if that means anything, but figured I’d throw it out there.
4 stroke carb the butterfly is partially open in idle. Most folks turn the engine multiple times because the compression gauge builds up to max compression read. Either way works just fine.
What I would do: Get a cheap ebay digital tach that triggers off (inductive) plug wire. The engine is rated for full power at 4000RPM. The chances that it has a "non standard" prop is likely nil. Get it warmed, adjust the high speed needle with the tach and for best performance, and if it turns up anywhere near 4K your compression is not an issue. What readings do you get pulling it hard with the recoil? Also if you have not, I would make an effort to check the gauge for accuracy. If it starts fairly easy, and turns up to rated RPM, you are good. I mentioned before to try and soak cylinders with ATF, same thing basically as Marvel in this case
Farmy, may I suggest you to do a PDR (paintless dent repair) on the fuel tank, then polish it up and/or put new clearcoat on it, essentially maintaining the worn/patina but sealing it/locking it up in a nice glossy finish, without the geometrical flaws it now has in the tank. Also, there's a chance the headgasket does not have fire rings (no metal) in which case you can at least fabricate your own. You could then also rehone the bores, so the existing rings can bed in again.
Greetings from UK, First visit to your channel but looks very interesting & varied, like you say some others are good but they tend to do the same stuff, just heard "it's alive ---sort of! Ha ha.
Hot vs. Cold compression check? It's like setting valve lash, or tire pressure..., it depends on what the company's engineers spec'ed. If the Johnson engineers sped'ed 70 PSI cold, then it should be checked cold (and engineers often do what is easiest, and cold is easiest), else hot.
I'm anxious to see that head gasket! If you have any youtube buddies with a laser cutter, its possible they could cut a new copper gasket out of proper thickness material. The fun part would be blueprinting the old one. I had an evinrude (70's 35hp) blow a HG. Mine was catastrophic enough to lose almost all compression. At least I was upstream of the launch ramp :-D Relatively easy fix.
Could most likely do a Rubbing to get a decent copy if you will, ive done that before on simple things, not sure how well it would some on things that protrude or flange etc but thats an option i would think. Oh theres also another thing that can be used, we use it to test Pressure on mounted items, Heat sinks on a cpu for example. The paper will change color where pressure is added, so maybe you could marry the 2 parts together and get a Print if you will ? Not sure but just an idea . Cheers .
The rings on the pistons over years of use will wear. Best case you can replace the rings, worse case you need to re-bore the engine block and replace the rings with slightly bigger ones. That is what used to happen 40+ years ago.
In my country, we don't worry about getting pistons rings and that stuff as original parts there are parts abound that are the spec. We just use those that fit. I live in Thailand and I don't see why America wouldn't have parts that would fit exactly, what I do is join a FB group they have all the answers there or the Johnson club in your case....
I agree. Finding parts is likely wishful thinking plus as is, it has character that a full restoration would essentially remove. Not being inclined to tinker with engines I know only basics, but I was impressed by the operation of the two cycle engine compared to the four cycle engine. The two cycle engine was prototyped.around 1880 roughly 20 years after the four cycle engine and while in a sense simpler it certainly took more thought to work out the details of its operation.
Make an adapter to go into your spark plug hole. Fill it with positive pressure and see if you can put more than what your compression makes. You can even get some soap bubbles and spray around the head to see if you find any leaks on the outside. Your head gasket could be not leaking around the outside or between cylinders but it could be leaking into the water jacket and exiting out that way. I'd definitely take a look at the bore too....if the cylinders got extremely rusty and you turned it over....it could've definitely fucked up some rings or scratched the bore pretty good. Just tossin some ideas out. I'm no expert by any means.
I'm only 58 but I remember those engines being a pain to run in the 1960's. I have a couple 2-stroke lawn equipment POS' that I would love to get rid of except the 4 strokes are nearly twice the weight.
I had a Johnson 5.5 hp that was 4 cylinders! Somewhere around 1952-55. It ran well until I left it sit for a few years. It pushed a 16’ nicely through the water.
Your engine was actually an Evinrude Zephyr then. That was the smallest production 4-cylinder ever produced. It was 5.4hp. Look them up! The later 5 1/2hp engines were a vertical twin design produced both by Johnson and Evinrude.
If you turn an engine slowly by hand, you can often hear the pressure hissing past the ring gaps. No matter many compression rings you have, it is still a leakage path. Albeit, it's a tortuous path through the gap in the first ring, around the circumference and through the gap in the second ring, etc. This is my anecdotal reference for saying cranking speed matters in a compression test. May the "Johnson" jokes never end! BTW I think your Johnson needs to be blown. You could literally design and build a supercharger for it with the wherewithal you have...casting, machining, etc. It would probably wreck your Johnson, but it would be a very cool project. Ok, I'll leave it at that. 🤣😂
You can check both warm and cold. It's really a reference and in many cases, manufacturers will specify what constitutes a valid test. If your values, based on specs, are within said specs, that is what you'd go by. You don't want a lot of variance between cylinders, if multi-cylinder. Warm is "best", but again, it's a reference value. What's good or bad is dependent on what the manufacturer is saying is "okay". There are some general values that you can go by, but again, it's just a reference. You did the right thing by using a drill to check compression. Imagine cranking a diesel over with a wrench to test it's compression. No, you'd use the starter.
LEAK DOWN TEST IT!! A leak down test will tell you the complete story. You put the piston at top dead center, hold it there, introduce air pressure and the gage will tell you percentage of leakage. By listening to the engine, you can determine, rings or head gasket. Even more useful on a 4 stroke
If you found this video helpful, please consider supporting the channel! Check the links in the description. Don't have any money to spare? Just shopping on Amazon through my amazon store link helps, even if you end up buying something not listed in my store. Doesn't cost you a penny!
Marvel Mystery Oil experiment is underway. We will see results soon, and also hopefully get to do a full rebuild on this engine. Please comment if you have information on parts for this powerhead! Have a great weekend everybody!
I wanted more jokes, was not disappointed LOL
Gotta say, I've been finding all these videos about your Johnson way more enjoyable than I would've thought.
You need the shirt. My Johnson is bigger than your Johnson. OMC is awesome.
Got it, they went to your home and shouted "vhere is zhe maney, or ve vill cut off your Johnson" right ?
Johnson TN-26 Compression
When I was a Second Lieutenant pilot trainee getting ready for my first jet solo, I pointed at an object with nuts that were safety wired into place and asked the grizzled old crew who was helping me strap in, “What’s that?”
He said, “Works fine, lasts a long time, don’t f*** with it.” Good advice with all things.
Doing your compression test, you had about 62 PSI on each cylinder. According to The Classic Outboard Motor Handbook (pp. 44-45), anything above 50 PSI is acceptable on a seventy-year-old Johnson.
Also, your compression readings on each cylinder were well within ten percent of each other, and there was little variation with or without a spark plug in the untested cylinder. It’s very unlikely that you have a blown head gasket with such readings.
One thing you could check without violating the crew chief’s advice is to check crankcase compression. First, check that the screws designed to hold the crankcase together haven’t vibrated loose. If they have, you might have found your problem.
If the screws are tight, remove the carburetor one more time. Place a tissue across the intake manifold and turn the motor over. If the tissue wiggles, there’s at least some crankcase compression. (Because of the crazy low speed needle operation on this motor, you might start by doing the same thing with the rotary valve intake.) If there’s no apparent suction in either place, or only a little, you might need a new crankcase gasket (ibid p. 109).
With your skills, I know you can make a crankcase gasket - head gasket, not so much.
I suggest following the crew chief’s advice, and just enjoy burning some 16:1 fuel and oil mixture through the old boy once or twice a year. That’s about all a seventy-year-old Johnson should be expected to do, right?
“Welcome back to Farmcraft. This is my Johnson.”
Never gets old.
I am ashamed by how much time I have spent watching him play with his Johnson. 😂
You ough to teach shop ... I've been wanting to understand this for years and like you I enjoy learning why something works the way it does Thanks John for explaining the way this works😊
man the owner's manual back then was a whole another level thing. Imagine getting a car or something today and getting a full breakdown on how the engine works so you could fix it whenever it breaks / modify it to suit your needs better
Most locomotive engines are 2 stroke diesels that operate in similar fashion. The crank doesn’t get fuel, but there is still a clever arrangement to get it all done in 2 strokes. As you were saying, it’s a great way to get good power to weight ratio, but on a locomotive you want a lot of weight. But running the engine at a lower rpm still gives good horsepower on a 2 stroke, so that is very desirable on a loco for longevity. Max RPM for an EMD 710 locomotive engine is under 1000 rpm. At max RPM a 16 cylinder makes 4500 hp, which gets converted to 3.1 megawatts in the main generator on modern locos. So… 2 cycle for a loco, big horse power, low rpms.
Never thought I would watch this many videos about another mans johnson.
All Johnson jokes a side though a bit of laughter sneaks out when you crack the joke..
Really enjoyed the explanation’s that you share in detail. Really helps understand functionality with the proven comparison your showing.
I truly hope you find another outboard to tinker on, I personally have learned alot from your “Johnson” and really any video you do you give all possibilities with details. The world is a smarter place having this channel available! THANK YOU.
Hello from Finland! I have enjoyed watching this saga. Old outboards are my hobby, specially been restoring Britsh Seagulls and small OMC engines from -70's.
Ever see or find any Archimedes Penta opposed twins over there? Only a few over here in the states. I worked for Penta for a number of years and would love to find one someday.
OMC'S Are awesome, do you have the book "Evenrude Johnson and the legend of OMC"? They used to have a large boat here in Milwaukee with every outboard on its stern.
Dude, you just have to accept that when your Johnson gets old it simply doesn't perform like it did when it was new, no matter how much magic lube you use.
Funny
Maybe try some Viagra or Cialis?
😂
I would think that is what he is doing... marvel mystery oil IS viagra for for an old Johnson isn't it?
🤣🤣🤣🤣
I’ve worked on outboards for 25 years and I’ll tell you that most smaller motors(25hp or less) with head gasket failure was between the cylinders, it’s usually the narrower part of the gasket. I believe your compression is perfectly fine. Compression on a two stroke rises with rpm, also the smaller volume combustion chamber doesn’t require as much compression as a larger one due to using less fuel/air mix. Just my 2 cents.
This channel is growing rather quickly. I’ve been around watching for a while now and I’m excited to finally see the recognition here on RUclips that you deserve!
Let’s hope at least try head gasket and rings if possible. The reed valve parts sometimes go bad on two stroke that sit a long time. The engine sounds pretty good now. Great project
Hopefully, if anything is bad with the Reed valve, its just something a good cleaning and polishing of the surfaces will fix. Hopefully it is just a bad head gasket and not a whole can of worms.
I spent last week tearing apart the rear end on the work truck because it needed a axle seal. That turned into almost having to replace the whole rear end. We're kind of Lucky it didn't just explode on us driving around in the hay field checking on the cows one day.
Your explanation of the two cycle engine is right on point but there is another factor which improves performance.
When an expansion chamber is attached to the exhaust port and tuned properly, it causes an impulse to occur just before the exhaust port os closed which forces any fuel air mixture which may have escaped back into the cylinder. It can in most cases improve the compression as well. Or something to that effect. It is cool to hear a motor tuned properly “get up on the pipe” and go like a scalded dog!
I had a motorized bike, nd I put an expansion chamber on it.
When it came "on the pipe" it was almost scary. Bicycle was
NOT built for that much power!
I've been playing with 2 strokes for about 1/2 my life. Yamaha
had a wicked fast street bike. RD400. Wish I still had one.
steve
Man can’t stop talking and working on his Johnson.
Something something throttle and strokes something.
One does not simply stop working their Johnson.
@@772tsweet77 Or Johnsons. :) My dad has a nice collection of them somewhere between 7 to 10.
Reaming a bore and extending the stroke along with using any type of power adder are my preferred methods of improving my Johnson's performance.
Thank you for schooling me.
I now understand the differences.
You did a great job explaining everything.
Thank you.
I own a 115 hp Evinrude/Johnson outboard.
I am not sure if it's a 2 stroke or 4.
I know now what to look for. Thank you for your help!
Keep Going. I had an Evinrude blow head gasket between cylinders, it ran poorly, spitting raw fuel out of exhaust. after a few seconds, motor quit and would beardly start, very little power, then quit after 5 seconds.
Small cylinders always show lower compression values than larger cylinders. The first thing to do is check what compression your gauge shows on a healthy running small engine maybe something like a chainsaw or brush cutter. If the values are also low then its the way the gauge works. I have had many small engine newly rebuilt show 80psi on my gauge but on my car hit 160psi with 250 000 miles. The fact both cylinders indicate very similar nimbers leads me to believe the rings are still good
I agree
I.E......"relative" vs "absolute" numbers. Comparing the pressure of one cylinder against the other, shows the relative relationship. But in this case, the concern is with the low absolute values. It's easy enough to test the gauge with an air compressor, to see if the absolute values it is providing are accurate.
@@ls2005019227 your theory is correct but in practice. All small cylinders show lower compression number than larger cylinders simply because of the volume of air being forced into the same space and that is compounded by the fact this is a 2 stroke with low compression ratios usually around 7:1
Was watching BigStack videos and found yours by accident. Browse through a few videos and love what u do. Earned both respect and subscription. Keep going my friend
I like your Johnson...series. I thought the series was over. I'm so excited that it wasn't quite. I wish I could help with my comments. But hopefully you will be happy enough knowing that I ALWAYS learn something when you make a video.
The hose length on the compression gauge will not affect the final compression reading, but it will take a lot more cranks to get to the final reading.
I agree, though I wasn't thinking of it when I shot this video. The check valve on the compression hose makes the hose length essentially a non issue.
That's a beautiful Johnson. Loving these videos.
A leak down tester is a better tool for checking engines, I've made my own and its a very handy tool. uses compressed air and any leaks are easy to find. great video's!
Wayne Pulley, formerly of Pulley's Marine on Gwynn's Island in Mathews County. He was a Johnson dealer for years and years. I just saw him earlier this month. He's long retired, but he can probably tell you exactly where to source all that stuff. Obviously I'm not going to post his number and whatnot on here, but he shouldn't be tough to find. Good luck. Awesome project. 👍👍👍
Can’t get enough of your videos!
Can't wait to see the upcoming episodes! I'm with you and most of us viewers....leave her looking as is and try to do what you can. Ultimately she runs!
Great explanation of the two stroke engine, thanks!
I had a similar situation with a 1959 Evinrude Fisherman Golden Jubilee 5.5HP Engine that somebody gave me. It had been sitting in a barn for 40+ years and didn’t run. It had low compression, and decided to take the head off. I found out that the part of the head gasket in between both cylinders was burned, which in turn caused the low compression. I replaced the head gasket, sanded down the aluminum head with 2000 grit sandpaper to make sure the head was evenly flat, then put the head back on, torqued it down to the proper specs, and voila, compression was back. I got the engine up and running again, and now I was able to move forward with cleaning the carburetor, and replace the water pump. It’s a great runner again rather than a static display.
I'd love to see more episodes on your Johnson... Wait...
I've been restoring a 1936 motorized two-stroke bicycle and love to see more in that topic!
it's surprisingly entertaining to see someone work one there Jonson ^^
Your having way to much fun playing with your Johnson!
Excellent diagnosis - UK
Just like any 2 stroke, pull off the muffler, turn over the engine by hand and look at the pistons and rings, if there are visible scoring marks or damage to the piston then you have your answer. If it looks good (which is subjective but I'm sure you're snart enough to make a judgement) then leave it alone. Look at the piston, is it all shiny (worn), scratched up (damaged) or are there some machining marks still visible (perfectly fine).
Also you may be able to measure the ring thickness which combined with taking the head off and measuring the bore size will help finding replacement parts.
Like i said previously, try run it with the best 2 stroke oil you can buy which is synthetic motorcycle oil (for water cooled engine) Motul 800 or Maxima or Amsoil etc. They have a much higher film strength which helps the oil stick around the rings and gives better sealing/compression, it works.
Not sure this engine will have reed valves, could just be Piston Ported?
Likely piston/port. Engines with reed valves should have raised compression, as well as improve fuel economy.
My guess for checking compression when cold is so that the baseline is comparable to the numbers the manufacturer setup if indeed they created those numbers for a cold engine.
thank you for your excellent education about 4 and 2 stroke engines!
As always a great video. Your videos and coffee make for a great morning
Hello from England
Thinking a simple hone buster used very sparingly will really make a difference.
Run some seafoam through with the fuel oil mix it really helps loosen stuck rings.
lastly any 2 stroke needs to be used hard. An Italian tune up makes the world of difference
It's a new PBS show, This Old Johnson!
10:18ish if the throttle is closed wouldn't that create a vacuum in the crankcase restricting the amount of incoming fuel /air interning the crankcase ? I think it would !
Another factor to consider, are the seals in the crankcase, if they are worn this can lead to the fuel/air charge being lost. BTW love your channel
I'm a systems analyst and I love the boat motor show... it feels like I'm watching my own job but with physical stuff
I would say hold on a bit! Fact is, compression gauges will very, but the compression of each is comfortable, and you have it running strong. You are right about going in deep can become a parts nightmare, and you know the old saying..."if it ain't broke, don't fix it!" It is pumping great, you've got that, starts easily (every old engine has it's own personality). I know you mentioned it in one of the vids but missed it. Not so worried about putting mystery oil or such in except when first messing about with the engine after sitting, but don't skimp on the oil mix. Lots of younger mechanics say you can use a thinner mix because newer oil is so much better... Bah! No! Use what is recommended for that engine, as it probably shows on the tank instructions if they still are there. It is not about the new oil, it is about the size and type of bearings. Outboards are under constant load when they are pushing. New oils may be less smoky. Many of the commercial river fishers used to use straight 30Wgt way back in the sixties. These guys used to smoke pretty well. Who doesn't love the smell of two stroke in the morning! :)
I do agree with the keep it original as well. That is a pretty engine as it sits. Hell, I'm 69 and I know a face lift won't make me run better! Worked almost exclusively on fifties/sixties engines for a small shop in Delaware way back, and with the USAF MWR when I was in Interlick Turkey where we kept a small fleet of old rental boats alive. Been messing about with boats ever since, albeit just enough to keep mine in the water. So run the little guy a good deal and see how it settles down. Protect it in the winter, keep any 10% ethanol fuel out of it or empty the system after each weekend. Very good vids!
I love the way you presented all the in's and outs. Discussed all the options. Marvel Mystery Oil we used that stuff everywhere, including on cuts as a disinfectant. I wonder if it would help the Arthritis in my right hand? ✌🤟🖖
Very interesting information. Thank you.
Great explanation of a simple two stroke. Wait until you get to work with tuned exhaust with a two stroke. Expansion chambers, properly designed can use the exhaust pressure wave created by the shape and length of the exhaust to actually have a supercharging effect at a very narrow range of rpm at the high end. During the overlap when both the exhaust port and transfer port being open, some fresh charge follows the exhaust out, but the bounce of the exhaust pulse will push that charge back into the cylinder in affect pressurizing the charge because the transfer port closes first. On the Kawasaki H2 Triple with racing chambers, going past 5000 rpm felt like you flipped a light switch, and it was hang on for dear life!
With a 4 stroke, shooting a squirt or two of oil into the cylinder before a second test will help determine rings or valve leakage. Could this work to help diagnose head gasket or bad rings in a two stroke???
You'd have to match the rpm at pull speed because that's all the more rpm that is available on initial startup. So if it runs at pull start rpm then it's obviously adequate to generate enough compression to run otherwise it would never start. Then once you've established compression at pull start rpm then you've got a base line to measure the increase at throttle rpm. So you'd have to put a timing light that measures rpm on a dead pull then measure from that point to whatever the factory specs claim rpm is at full throttle. Two strokes are a pain in the ass to diagnose but it's honestly probably your red valves from sitting so long they get rusty along the outer edges closest to the ports and then as you run it the heat burns off the thinner compromised material and steadily reduces efficiency until it just won't hold enough viable compression to start and run.
You can sometimes get low compression and yeah the components aren’t warm but the piston rings have lost the spring in them from possibly being overheated or just age it is possible to put some spring back into the ring but it is a last resort if you can’t get new rings I’ve done it in the past by stretching the rings over an old piston and blow lamping The ring until it is glowing cherry red I’m not sure whether I should have quenched the range at this point I didn’t but I got reasonable result but I would recommend this is a last resort cheers Derek
On two strokes, there is a bit of a dynamic effect to the intake portion of the cycle. It's not easily explained in a comment, but there is a bit of a supercharging effect happening in the crankcase, as well as a scavenging effect with the exhaust leaving(Though not nearly as much when just turning it over as opposed to it actually running), so compression is more RPM dependent than normal even when everything is in good shape. Not to mention there's always some degree of dynamic compression that comes into play due to blow-by. That's not to say that there's no issue with the head gasket in your case, just pointing that out. But none of it is really a factor you should worry about much. Your tests are perfectly fine. Fortunately, it's a two-stroke, so it's really easy to get in there to see what's going on. Unfortunately, finding a replacement head gasket may be significantly less easy. As for Marvel Mystery oil, great stuff, I absolutely love it. It's awesome for breaking free a seized up cylinder in my experience. But it won't do squat for lost compression, nor do I see how it possibly could except for one oddball possibility that wouldn't apply in your case as you've already had it running for some time.
It really is a cool little motor. As a mechanic by trade, it makes me all warm and fuzzy inside watching you keep her ticking. Lol.
I've seen some videos explaining how a two stroke engine works and particularly find this explanation the easiest to understand, even thoug my mother language is spanish.
such a cool johnson!
Great work in that old Outboard. If cylinder bores are chrome plated and worn too much that's going to be a challenge but not impossible maybe bore out and resleeve if block is thick enough or have them replated. Pistons rings can be bought according to size needed. Bearings or bushing will just need to be machined out to fit. I would try Amsoil and see what happens. Good luck,waiting on next installment.
Isnt it amazing that an owners manual used to have an explanation on how things work!
A compression check can be done with the throttle closed on a 2 stroke maybe if an engine is warm.
Compression check: If you are relying on air to enter the cylinder via exhaust port (throttle closed) would muck, carbon chunks or rust not potenbe drawn back into the cylinder, especially if the engine has been standing for example..just a thought.
Don't tear the powerhead apart yet. I found my Johnson Service Manual (10th edition), and my TN-26 Owner's Manual. I think your Johnson might not be too far from normal. (Regarding compression, at least :)
I gave myself a brain blister trying to calculate piston displacement, compression ratios, and PSI tonight. I'll try again in the AM when that Rusty Nail has worn off.
I think that it's important to point out that crank case supercharged, flapper valve 2 stroke engines are thought of as representative of the 2 stroke cycle in the US, but they are actually a corner case of 2 stroke cycle motors overall. It is possible to use the engine layout shown above to make an extremely simple/cheap but also extremely dirty 2 cycle engine, which despite requiring some form of intake charging is still simpler than a 4 stroke due to the lack of valves. That is by no means the only 2 stroke layout: the biggest, most efficient engines on earth are all 2 stroke, and the oil path is indistinguishable from a 4 stroke.
2 stroke engines, because they lack an intake stroke, are necessarily the flithy, crank-case charged "Weedeater engines" that we are familiar with IF they lack some other kind of intake charging and direct fuel injection. In the 1950s-2000s, when big, normally-aspirated 4 strokes were the norm, the only clean 2 strokes were huge engines like the Detroit -71 series. However, any engine using positive pressure charging and direct injection has met the difficult threshold for making a clean 2-stroke, and those features are increasingly common now. For instance, the entire Ford Ecoboost line already has all of the expensive parts of a 2 stroke (direct injection and turbochargers), such that converting the design to 2 stroke would actually involve making it simpler/cheaper to build. Thus, the idea that a 2 stroke engine can only be what we have seen thus far is deeply misleading. For a design with a presence on youtube, you might check out Achates Power, which is a modern variation of the old Junkers Jumo/Fairbanks Morse 38 8-1/8. More conventional SCCI 2 strokes whose development was sponsored by the SAE are also getting similar thermal efficiency, up to 55%, with soot/NOx emissions which are significantly better than current production 4 strokes.
This is a really cool and old 2 stroke radial diesel 2 cycle: ruclips.net/video/ZMVHflfCdmg/видео.html . It's pretty easy to find videos of Detroit -71 series motors, and those are all 2 stroke diesels as well.
i am loving this series, i have a '39 "HS 39 Johnson" and am trying to resurrect (her) but i fear the quick action magneto is faulty. i also have a canadian OK15 from the 40's suffering a no spark syndrome. your series has given me hope
If a motor has sat for a lengthy period without running the oil in the bore can have dried/evaporated or seeped away affecting a compression test. Otherwise, unless doing a wet test (adding oil to the cylinder after a dry test to potentially indicate where a known loss of compression is occurring ), the vast majority of the compression tests I've performed have shown little difference between warm and cold readings on a recently operated engine.
a quick way to check the rings would be to push a bit of engine oil into plug hole. if the bores/rings are bad you will see a substantial increase in compression
I agree on the: if something is old shouldn't shine like new. It should work, yes, but the patina of time should be there.
Great opening. You have a nice looking johnson.
I run a 1999 Evinrude Johnson Oceanpro 200 two-stroke on my dual console boat. The starter spins the rotating assembly about as fast as your drill on high. Not sure if that means anything, but figured I’d throw it out there.
I have to admit that I found this video about a man's dysfunctional Johnson more interesting that I would have thought.
Thanks for an interesting video.
4 stroke carb the butterfly is partially open in idle. Most folks turn the engine multiple times because the compression gauge builds up to max compression read. Either way works just fine.
What I would do: Get a cheap ebay digital tach that triggers off (inductive) plug wire. The engine is rated for full power at 4000RPM. The chances that it has a "non standard" prop is likely nil. Get it warmed, adjust the high speed needle with the tach and for best performance, and if it turns up anywhere near 4K your compression is not an issue. What readings do you get pulling it hard with the recoil? Also if you have not, I would make an effort to check the gauge for accuracy. If it starts fairly easy, and turns up to rated RPM, you are good. I mentioned before to try and soak cylinders with ATF, same thing basically as Marvel in this case
You should check the thickness of the cylinder head gasket. A small difference in thickness can make a big difference in cylinder pressure.
Farmy, may I suggest you to do a PDR (paintless dent repair) on the fuel tank, then polish it up and/or put new clearcoat on it, essentially maintaining the worn/patina but sealing it/locking it up in a nice glossy finish, without the geometrical flaws it now has in the tank.
Also, there's a chance the headgasket does not have fire rings (no metal) in which case you can at least fabricate your own. You could then also rehone the bores, so the existing
rings can bed in again.
Ki
Looking forward to seeing more of your Johnson!
Greetings from UK, First visit to your channel but looks very interesting & varied, like you say some others are good but they tend to do the same stuff, just heard "it's alive ---sort of! Ha ha.
Hot vs. Cold compression check? It's like setting valve lash, or tire pressure..., it depends on what the company's engineers spec'ed. If the Johnson engineers sped'ed 70 PSI cold, then it should be checked cold (and engineers often do what is easiest, and cold is easiest), else hot.
I'm anxious to see that head gasket!
If you have any youtube buddies with a laser cutter, its possible they could cut a new copper gasket out of proper thickness material. The fun part would be blueprinting the old one.
I had an evinrude (70's 35hp) blow a HG. Mine was catastrophic enough to lose almost all compression. At least I was upstream of the launch ramp :-D Relatively easy fix.
Could most likely do a Rubbing to get a decent copy if you will, ive done that before on simple things, not sure how well it would some on things that protrude or flange etc but thats an option i would think. Oh theres also another thing that can be used, we use it to test Pressure on mounted items, Heat sinks on a cpu for example. The paper will change color where pressure is added, so maybe you could marry the 2 parts together and get a Print if you will ? Not sure but just an idea . Cheers .
PLEASE give any links for parts that you find . I got a couple these old out motors up in the attic.
I looooooooove you Johnson, when I grow up I want the same !
Your two stroke Johnson came with a users manual?!
Very interesting!!! Here’s hoping the Marvel Mystery Oil experiment is a success!!! 🤞🏻
great explanation!
Opening line, priceless. You missed the power head hidden joke though
The rings on the pistons over years of use will wear. Best case you can replace the rings, worse case you need to re-bore the engine block and replace the rings with slightly bigger ones. That is what used to happen 40+ years ago.
Respectively, check the condition of the crankshaft seals. Your compression is dependent on the "charge " from there
In my country, we don't worry about getting pistons rings and that stuff as original parts there are parts abound that are the spec. We just use those that fit. I live in Thailand and I don't see why America wouldn't have parts that would fit exactly, what I do is join a FB group they have all the answers there or the Johnson club in your case....
How is the compression during a "wet" test? Give it a couple squirts of motor oil in the cylinder before doing a compression test.
I agree. Finding parts is likely wishful thinking plus as is, it has character that a full restoration would essentially remove.
Not being inclined to tinker with engines I know only basics, but I was impressed by the operation of the two cycle engine compared to the four cycle engine. The two cycle engine was prototyped.around 1880 roughly 20 years after the four cycle engine and while in a sense simpler it certainly took more thought to work out the details of its operation.
Knowing NOTHING of engines, that is a very interesting fact.
Thank you for giving me such an intimate view of your Johnson.
Make an adapter to go into your spark plug hole. Fill it with positive pressure and see if you can put more than what your compression makes. You can even get some soap bubbles and spray around the head to see if you find any leaks on the outside. Your head gasket could be not leaking around the outside or between cylinders but it could be leaking into the water jacket and exiting out that way. I'd definitely take a look at the bore too....if the cylinders got extremely rusty and you turned it over....it could've definitely fucked up some rings or scratched the bore pretty good. Just tossin some ideas out. I'm no expert by any means.
I'm only 58 but I remember those engines being a pain to run in the 1960's. I have a couple 2-stroke lawn equipment POS' that I would love to get rid of except the 4 strokes are nearly twice the weight.
I had a Johnson 5.5 hp that was 4 cylinders! Somewhere around 1952-55. It ran well until I left it sit for a few years. It pushed a 16’ nicely through the water.
Your engine was actually an Evinrude Zephyr then. That was the smallest production 4-cylinder ever produced. It was 5.4hp. Look them up! The later 5 1/2hp engines were a vertical twin design produced both by Johnson and Evinrude.
Do a static pressure test in lieu of compression test to check for leaks. add oil to confirm head or rings.
Doesn't air gas mixture go into the pressure gauge and if so why doesn't it harm it over time?
If you turn an engine slowly by hand, you can often hear the pressure hissing past the ring gaps. No matter many compression rings you have, it is still a leakage path. Albeit, it's a tortuous path through the gap in the first ring, around the circumference and through the gap in the second ring, etc. This is my anecdotal reference for saying cranking speed matters in a compression test.
May the "Johnson" jokes never end! BTW I think your Johnson needs to be blown. You could literally design and build a supercharger for it with the wherewithal you have...casting, machining, etc. It would probably wreck your Johnson, but it would be a very cool project. Ok, I'll leave it at that. 🤣😂
I like the patina too. But put a clear coat on it to protect it
My suggestion is put it on a stand, crack open a beer, and just take up canoeing. 🤪
What do the cylinder walls and rings look like?scratches?
You can check both warm and cold. It's really a reference and in many cases, manufacturers will specify what constitutes a valid test. If your values, based on specs, are within said specs, that is what you'd go by. You don't want a lot of variance between cylinders, if multi-cylinder. Warm is "best", but again, it's a reference value. What's good or bad is dependent on what the manufacturer is saying is "okay". There are some general values that you can go by, but again, it's just a reference.
You did the right thing by using a drill to check compression. Imagine cranking a diesel over with a wrench to test it's compression. No, you'd use the starter.
Hi All
Great Vid's
I am sorry to say
I think u missed a few seals
It's your fault &
It's your
great sense of humour &
u invented it
LEAK DOWN TEST IT!! A leak down test will tell you the complete story. You put the piston at top dead center, hold it there, introduce air pressure and the gage will tell you percentage of leakage. By listening to the engine, you can determine, rings or head gasket. Even more useful on a 4 stroke
how do 2 cylinder 2-stokes not interfer with each other. Are they in phase?
You know, There are things you can to do increase your 2 stroke Johnson to at least a 9 - 10 stroke..... :P