Tecumseh Trouble - Engine Misfire and Melted Tank

[@LukesMovies]

Seriously I love that you don't make your videos short! Please never change that. It's one of my many favorite things about your channel, the other thing I love about your channel is how much depth and attention to details you put in and you're extremely skilled at working on small engines. Your content is pure gold. Thank you for your time and pubic service to your viewers don't ever change how you make your videos ☺️

[@johncourtneidge]

Agreed!

[@stevevogelman3360]

Pubic service….hilarious

[@georgedyson9754]

Yes, I am also perfectly content with long videos! Keep them going.

[@LukesMovies]

@@stevevogelman3360 in a way it is kind of a public service he’s doing this to help people, you don’t have to be a jerk

[@craigl3009]

I was a mechanic for years and eventually owned a small engine shop when this engine was new. My shop was a master service dealership. I have 2 comments. First these flat head Tecumseh engines never were known to be smooth runner's. . 2nd your not considering a sticky governor. Start with checking the governor rods. For abnormal bends , and spring condition, some models in the series also had a secondary spring. To help stableize movement of the governor rod. It seems you covered all the other likely conditions well.

[@eugeneoreilly9356]

The governor problem would also explain the hunting at low engine speeds.Sticking flyweights could cause erratic running but I don't know about a high speed misfire.

[@a4000t]

Those things shook like Hunter Biden when he runs out of crack. Poorly balanced in my experience. That being said i don't think some had carb's matched properly. many used that offset flywheel key that could roll over but not shear and throw the timing off.

[@carlmatyas9920]

😮​@@a4000t

[@kevinmills5293]

The non standard exhaust may be causing back pressure issues (not enough) and the misfire.

[@fluffybabypolliwog]

@@kevinmills5293 I was thinking the same thing. Running out of suspects ...

[@thomasstewart9368]

You're not alone. I "had" an 8 hp techumsa with exactly the same issue. It was on my log splitter I owned for 20 years. Because it would "run" crummy I just let-err-rip spit & sputter while I split wood. Every year or two I'd try fixing it. I did everything you did 10-times over 20 years. My carb was NLA & the closest carb I could get was for a generator. That didn't fit or work well at all. I bought every carb part available for my engine. What I ended up doing that fixed the hard starting & running ruff was....the little brass screw in jet on the top side of the carb ..... I used a finger drill & made the through hole (not the tiny side hole) larger one drill size at a time. That finally fixed it - Yahoo & sold the log splitter. I ever see another 8 hp techumsa I'm not fixing it - whatever it takes to replace it would be a shortcut. Grrrrrr8 video 👍

[@capt2278]

that would make sense as he mentioned he has to run at half choke through most of his video meaning he has to cut down on the air supply. Could mean he isn't getting enough fuel? hmmmm

[@rogersemple3122]

Most people today will dump it and head to Harbour Freight.Time and money saved !

[@daivdash]

I have that log splitter. Leave it parked in the barn for 6 years with fuel in the tank and pull it out leave it all winter covered with snow. Put fresh fuel in it in the spring. Hit the primer 3 times and start it. Seems to have been what mine wanted. Runs better now than when it was new.

[@4Truth4All]

James, I had a Coleman generator like this and it ran the same way from new. It ran fine under load but stumbled occasionally when not under load. I never got it figured-out. I appreciate your efforts and don't mind the length of this project, this is the second time I've watched it and have learned more this time around! Keep up the good work.

[@martinflanagan2506]

Another great video James ,2 tricks I use. Valve lapping suction cups are prone to not sticking very well, I now use a 3/4" dowel and stick it on with hot melt glue , works great. The other trick is when grinding the valve stem use a vernier caliper to measure valve length before grinding. Saves putting valve in and out of the block to measure the clearance. You get top marks for persistance.

[@jcondon1]

Thanks for the tips.

[@doseven]

@@jcondon1 You can use a few drops of rubbing alcohol where the glue meets the materials and it will cause the glue to pop right off!

[@adamfletcher4262]

Yeah I thought about hot glue

[@CliffLewis28]

Great tips! 👌

[@waynedavies3185]

When doing valves, I also use double sided foam tape, but instead of using the valve tools as shown, I use a piece of dowel wood. It works great. I never have issue now doing valves. I get them done easy as tying my shoes. The dowel never slips off till I remove it from the two sided tape and I can apply far more pressure while spinning the valves and not have them slip. I threw my valve tools away.

[@Mrcrowley1967]

Length doesn’t matter when there is good content James I love going through the trouble shooting with you and the group

[@scottdavis9442]

That’s what the wife says, length doesn’t matter as long as it’s good content.

[@CliffLewis28]

@@scottdavis9442 🤣

[@parkerbirch5286]

How deep you plow doesn't matter, it's how long you're in the field.

[@jayjudd6518]

I could listen to the guy all day.

[@maurice5447]

I had the same problem and it was trash I the carburetor

[@jeanbaptistevallee4500]

A two hour fix it video first thing in the A.M.. I like it!

[@haneyoakie14]

That was absolutely worth 2:15 of my time. I have a similar unit that has been under the bench taunting me. After the comprehensive video you put together, even though the machine is not 100%, I gained enough knowledge to give mine another shot. I appreciate that you took the time to show almost everything. You presented fuel, spark, timing and compression and gave each one it’s due. No one can do that in 59 minutes. Your length of video meant you could show all the complexity, and you share your process and you thinking. That is where your content has more value than most. Thank you for this video. It gives me confidence that I can try to take on a similar challenge. You have helped me a lot in the past and you continue to do so here. 6 Stars, on the 5 Star scale.

[@johnbrizendine7716]

I totally agree!!! I love these longer videos!!!!

[@YukonHawk1]

I completely agree. It was worth every last second!

[@fredrickwright5975]

O

[@jodymorgan9869]

Are usually Speed the video up when I watch these unable to get through them a lot faster and if I need to I can always rewind.

[@carlbrown5150]

I worked on small engines at a rental company. I have seen coils weaken after they warm up.!!😉

[@matsurikudo5130]

After i just found this video and watched it,i can see what my grandfather said was essentially true,he worked at GM for 40 years and knew his way around engines and such,he owned numerous Tecumseh powered yard equipment tools over the years,and what he said was "they (the Tecumseh engines) like to be put to work" and now i realize what he meant,also fantastic videos,keep it up John!

[@avitiello100]

James, have you considered tired/week value springs. The compression will test good, but week springs will not follow the cam accurately at speed, causing the intermentent misfire you're experiencing. Take them out and measure their height. And while they are out, clean the carbon and lap. Good luck. Really enjoy your videos. They are a part of my weekly must-see video list on KZbin.

[@markholtrop8561]

I think you may have a valve floating issue. Weak valve springs will do that. It would explain your higher leak down at lower pressure as well. While you did lap the valves in, your exhaust valve may be ever so slightly warped or bent as well. I'd try some valve springs.

[@toopersistent]

Jim, During the 1980s, Kohler had a reoccurring problem with valves or valve guides. Similar symptoms; but, with additional occasional caveat! The exhaust valve would stick in the open position, until the engine cooled. The engine would suddenly die, and have no compression for several minutes. Eventually there would be a LOUD snap, and could then be restarted with ease. Thus, As did MarkholtropXXXX (9 months ago), I suspect a bent or warping exhaust valve. Once, we cured the problem in an Allis Chalmers Garden Tractor, by cleaning/reaming the valve guide. That unit had replaceable guides, but we lacked ready access.

[@qalliicha]

Nanci 😂😢😮😅😊f

[@shearn3162]

I can't believe I watched all 2:14 of this! That's a testament to the quality of your content, your vast knowledge and your determination to get things done right. Your video definitely did help me. I now know to avoid alllll things powered by a Tecumseh! Ha! Some of your other videos have definitely helped me rehab a Briggs carburetor. Thanks a bunch and keep them coming.

[@Trumplican]

ah you gotta understand though one engine having issues isnt a reason to avoid that brand

[@mahmoodbhamji6279]

Nor can I! It was just watching this man's sheer determination. I have to give him full credit for his perseverance. Thank you. And endeavours.

[@jonminer9891]

Ha! I have not seen you working 4 hands. It was a lot of work but the end justified it. Thanks for sharing! Stay healthy!

[@oldsranch]

Compression ring with low tension, or weak valvespring(s), those are my guesses. Both would show better performance under load for this small engine application. Anxious to see the follow up on this one!

[@johnh8268]

I was thinking weak valve springs too.

[@blackcat31w]

I bought a Troy Built tiller with an 8 HP Tecumseh back in the 90's. I still use it and it runs about the same as the one in this video. I gave up years ago on making it run smooth. My suggestion is to move the engine to your garden tiller. 😄

[@NY411Info]

lol

[@grahammoss5373]

I don’t know the first thing about small engines except how to use them. Your methodical approach and excellent narration kept me captivated all the way through. I hope you sorted the problem for your own sanity.

[@johncourtneidge]

Yes!

[@royhedrick8099]

I have had some similar issues before, I always go to the coil where it mounts. I remove it and clean the mounts on the block and clean where it mounts on the coil, then I use a little silicone grease before I regap the coil. It fixes the problem about 50% of the time. I hope this helps you your videos are very helpful especially on the generator side.

[@jcondon1]

Forgot to mention that, but did clean the coil mounting location and the old coil as well where it meets the block.

[@michaeltarasenkoop2389]

To prevent the tank from getting hot due to heat shield being to close place a spacer bar to raise tank up higher above the mounting bolts with spacer material

[@jimbrewer2893]

@@michaeltarasenkoop2389 I have used heat shield material as added protection.

[@Mrcrowley1967]

Did not read all the comments but what about the lobes on the cam shaft ?

[@garbleduser]

@@Mrcrowley1967 This is the comment I was looking for!

[@firestorm.v1]

I know it's not the same application, but when I used to maintain a fleet of pushmowers and other motorized small engine equipment, Tecumseh always proved to be problematic for weird things like this. They were always the more tempermental units to get running and even then, they would never act really *right* when compared to B&S, Champion, and other small engines of the same form factor. I'll be watching to find out what you find out in your investigation, but that's definitely a head scratcher. From what I can tell,. you've gone above and beyond, this thing should be running like a top by now.

[@PaulMack1249]

Hi, Jim…as you know, my field of expertise was electronics and not gasoline engines. When you made the initial test for spark I observed a really strong spark appearing on your tester. This got me thinking of possible leakage from the secondary of the coil to ground intermittently, or even from the spark plug wire itself. I used to see this happen on the secondary side of flyback transformers in older televisions that I used to repair which provided the high voltage to the CRT. Sometimes, the insulation on the second anode lead would fail and cause intermittent arcing to ground. They made a substance called Glyptol in a spray can that could be applied to the entire transformer and second anode to restore the dielectric properties of the high voltage system. It sure looked like that could be your issue until, at the end of the video, you showed where you actually replaced the coil, which pretty much blows my theory to bits. When you’ve gone through everything as thoroughly as you did and eliminated just about every possibility, you might consider a manufacturing flaw in that specific unit, one that is so small that it’s impossible to detect yet significant enough to cause the misfiring. Good try, pal. At least now I know you’re human! 😂 You’re still the best I’ve ever seen, very helpful, and most entertaining.

[@aerotro]

I think your right I seen that too.

[@DeadKoby]

Your scenario was plausible indeed, until the coil replacement. If one could start the engine with the cover off and observe, perhaps we would learn something.

[@brainndamage]

It could be sparking at the shutdown tang because that still has relatively high voltage pulses on it and is out exposed in the elements. It was even painted over which could be trapping dirt or moisture.

[@robertrich5774]

Could be kill switch wire it self dry rotted insulation or arching intermittent.. causing intermittent missing

[@robertmorin6495]

Yes that's possible. This engine also has a "low oil shut off switch" which may be bouncing on and off too.

[@OnTheEdgeNow]

An easy way to check for vacuum leaks, or to check the fuel mixture is with a propane torch. By turning on the torch without lighting it you can introduce the propane gas into the carburetor and it will change the mixture without actually adjusting the carburetor. You can run the motor at the problematic RPM and see what changing the mixture does. This helps isolate a fuel mixture problem. By using a torch with a rubber hose attached, you can look for vacuum leaks. This eliminates spraying flammable liquids in areas where it would cause trouble. It looks like when it is backfiring flames are coming out of the muffler. My guess is the exhaust valve is sticking. If it was rings you would see excessive blow by out the crankcase breather. I didn’t see what condition the spark plug was in, but I would make sure it is the proper plug. I would replace it. I have seen spark plugs do strange things.

[@markward7556]

I have a 13hp Tecumseh on my lawn tractor. It uses the same type ignition coil. I used a timing light to check timing, they run it at 30° before top dead center. Some engines miss under light throttle with this much timing, I suggest trying an offset flywheel key if you find out your ignition timing is as mine at 30°. You can use a battery powered timing light to check this and mark the screen behind the starter with a chalk line at top dead center. My Briggs & Stratton generator only runs the timing at 0° top dead center.

[@michaeltarasenkoop2389]

I had a tecumsoms gen and it ran for a long time without any problems for a long time ! The older machines seem to be built much better built ! Than the newer ones !

[@akdenyer]

Hi James, to get burning gases out of the exhaust can only be a few things. Bad ignition timing I.e too late, sticking exhaust valve. Excessive un atomized or large particle fuel in the combustion chamber. An interesting experiment would be to run it on LPG or NG as the fuel is already in a gas form. This would eliminate poor carburation. Fuel injection would have a similar effect but hard to do on a budget. Some newer B&S engines have fuel injection now. We deal with 100’s of small engines at work but mostly Honda and Lifan Some Kolhler and Kubota and B&S. Interesting issue I would love to get the scope on to try and see what is really going on. You could try a video of the valve operation and then view the video in slow motion to see if there are any anomalies.

[@sergey8644]

Since you checked almost everything on the engine side, please check the generator side. If there is an intermittent short within the generator, it will introduce a brief large load on the engine. At small speeds this could be impacting the engine. Connect an oscilloscope to the outlets and check if the wave is stable.

[@sta3539]

I had a bad bearing on the output side of an old Pincor that was causing a similar issue when it would feel like getting sticky for a second

[@eugeneoreilly9356]

The output waveform wouldn't be stable with a misfire anyway.Any brief interruption of engine speed will distort the waveform.

[@killermacmc]

When James fails, the viewers win. I love long-form vids from you.

[@johnwells5113]

Hi James my name is John Wells I am from the Philadelphia Pa area and pleased to be subscribed to your Channel James .I watch you tare these Machines down every day i can keep up the Great work my friend love John from Philadelphia . I love making dead engines run again alive❤

[@k8ble]

don't worry about the money you throw at it , look at it like you paying for a education, its an education we learn..if you dont sell them you could always rent them out..great job as usual.

[@WaqarAli-zg3wb]

A great video. One suggestion is when watching for spark using light, record the spark light at high speed and watch back. At 400 frames per second you spot the missing spark.

[@richlocker1458]

Hey James, love your videos! I haven’t read through all the comments, & I know this video posted 7 months ago. Perhaps you’ve already found the answer. Based on 25 years experience, I think the intake guide clearance is excessive, causing the cylinder to pull air out of the crankcase. Especially when the engine has the most vacuum ( idle & no/light load at rated rpm. This also explains the hard/erratic starting. Went through the exact same thing with an HM80. Ran great under load, couldn’t make it idle properly, did everything as did you. Intake to guide clearance. Tecumseh makes 1/32” oversized stem valves.🇺🇸😊

[@TC-uy8ng]

Your videos are never too long, regardless of the outcome. I learn something from you every time, You are a BOSS!

[@somerandomguy3868]

You really did battle this one, it so happens I learned small engine tuning on Tecumseh and they are very forgiving about carburetor settings, I have found a new spark plug helps even if the engine still runs on the old one, nice job James

[@LouisMednick]

I'm certain that this solution I'm about to give has already been stated to you. This happened to me on a mower. I had an intermittent misfire, similar to what you experienced. I checked everything and just couldn't find it. I was 100% sure that it was electrical and guess what? It was. But, nothing that I had experienced before. The issue was the kill wire. If you think about it, it just doesn't make sense. But, considering the time that I already put into, I figure that I should continue down a road that I was sure would end in disappointment. Much to my dismay, I found the issue. I unplugged the kill wire and the misfire stopped! I pulled the fly wheel and found the issue. The kill wire was rubbing against the underside of the flywheel. When the engine was cold/cool it ran pretty good with only a small amount of misfire. But, as it warmed up, the misfire would continue to get worse. The wire was bare on one side and cracked on the other side of the insulation. I replaced the wire and voila, the misfire stop.

[@martyb3783]

Even though you haven't solved the problem yet, this was an awesome video. I ALWAYS learn from your videos and it was absolutely worth 2:15. Great job! I hope someone comes up with an answer for this.

[@chrispixx]

Once you first got it started and found it was producing electricity, you should have just repowered it with a predator engine. I do appreciate your persistence and attention to detail. It was a very interesting video.

[@ludwigr.reindl4146]

Let me reiterate: it works well under load and that's when you need it working the most. Perhaps it is a tolerance issue in the manufacture of this engine, or there is another worn part somewhere in that old engine. Thanks for the great videos. :-)

[@mikerossman9863]

Good idea with the 2x tape👍🏻 I don’t think I’ve ever not heard them old Tecumseh engines not pop and miss no matter what they were on. They hard to kill if maintained.

[@johnbrizendine7716]

May want to check the cam, if the cam is a bit "wobbly" it will cause these intermittent and sometimes unreproducible issues. Though it mainly affects Briggs engines from the late 2000s where the cam shaft comes loose from the gear, but there may be a burr or something like that on the cam lobe or a sticking lifter/tappet.

[@JimUntershine]

I admire your persistence - It's heart-warming. I try to never let the value of my time exceed half the yard sale value of a project. "It's a Tecumseh - It's part of the charm" "It may sound like shit - But it starts every time and will power things up" "You'll get used to it" :)

[@rickkerns3164]

I have this same engine and after a few years, it exhibits the same exact behavior as yours. Mine is used to power a chipper shredder. I followed the same exact path you did in the video several times over the years but was never able to get rid of the misfires either. It’s the only engine (I have probably 15 or so engines across all the brands) I was unable to bring back to perfect. Finally, I set it aside and swore to myself I would not waste any more time with it, lol. And, I’ve never bought another device with a Tecumseh engine on it either. Crazy engine for sure. It will be interesting to see what you find if you open up the lower engine.

[@lewiemcneely9143]

I am with YOU! I HATE them! I wouldn't swap a Briggs or Kohler for their whole factory. OR Robin!

[@baileyhatfield4273]

I got a free Craftsman mower with an older like 13 horse Briggs flat head. Originally i messed with the carb, nice and clean, it started PERFECTLY, ran ok but had like pops. Carb adjustments did nothing, kind of leading me to beleive carb. Also was blowing a good bit of air back through the carb. Thought it was weird, already had a new plug just because its cheap and it looked original on a 15 year old mower. Checked and the intake valve was not sealing and leaking compression, zero lash either. Got a gasket ect, lapped the valves, adjusted the lash to spec, everything should be good, yes? Well now when i adjust the carb it actually does something, still pops, it will go and run, just it doesn't sound as nice as it should, being everything is so nice and perfect. Annoying spending the time, not because it doesn't work, but because you want it perfect and it didn't really help. Not gonna throw it by any means, but its something else.

[@lewiemcneely9143]

@@baileyhatfield4273 I've got one like that that the governor is very sluggish on. An 85 model 4 horse flathead with an 'all climate' carb on a Snapper 21. Didn't make many and info is less. I got a real Briggs book for all flatheads from 86 on I think but hardly anything on that engine but even less on the carb. I think i have an angle on it but will have to wait to see. Never had a Briggs to run sorry. Tecumseh? OH yeah. IF the mower had a hood scoop to pull fresh cool air in through slots in the hood to the motor intake screen and it's gone, rig one back up again. The hot air gets trapped under the hood without the foam between the hood underside and engine and it gets way too hot. I also run DELO 15/40 Diesel formula lube oil in all mine and my truck. Thicker oil lubes better and cools better.

[@shatnersufolanded7785]

Just picked this one up today for 35 dollar I am so glad you did this video. I'm going to watch this before I even jump into mine.

[@stephenlawyer3031]

Any time you remove the head on a Tecumseh engine it is always a good idea to take an indicator and check the timing as just a change of .001 thousandth of an inch on the points can make a change in the timing. I owned and operated a shop for several years and was a certified repair and warranty center and found this to be a common problem.

[@terrydouglas2777]

I was thinking what about the points and condenser when he removed flywheel to check the key. Tearing that far down, I always checked to see condition of the points if they have a burn spot on it. Plus, I might look old with a long white beard on outside but the kid in me loves to charge up the condenser from the motors when I put new ones in. Then sit it on the table and wait. When you hear a yell you caught one. They always just need to pick it up and look at it to see what it is. Touch wire and housing at same time with bare hands and win the prize. I use to set out about 10 to 20 per week back in the 1980s. Ah the good old days. An I know alot of you reading this did the same thing. Great minds think alike. Just like grabbing a electric fence a only hold it for half a second an say nope it's not on. Then someone else always has to check it. Bigger yell. Hahaha. We had so much fun but nobody got hurt, we did get some good deep scars back then but most have faded since that time. Great video buddy. Stay safe, wear rubber gloves.

[@baratono]

No points on this model engine. Electronic ignition.

[@benjamincresswell3713]

@@terrydouglas2777 Hi, when he had the flywheel off, there are no points or condenser. Tecumseh is using the B&S points eliminator coil. It has a trigger coil and a couple of npn transistors to start the electron flow and then interrupt it. So, no points on this setup.

[@NY411Info]

@@baratono lol I know, wtf. Also .001 on the points would not make a difference in running anyway. It's not rocket science. It's a old school engine, they aren't too picky.

[@chrisdevitto4340]

Working on a hm100 on a 5000 watt devilbiss gen, same problem exhaust valve no clearance, did valve job new head gasket, then carb same issue exactly misses at no load, but under load good. Compression 60+, will check coil and wire but beginning to think about weak valve springs or low oil sensor problems. Thanks for the good work.

[@gregblack2628]

Well here I lay with busted ribs. This made my night Lord knows I can’t get comfortable enough to sleep much less do anything right now learning The details are fantastic feel like I went to class. The BEST PART IS Knowledge for all my small engine machines. THANK YOU.

[@atlas3863]

good work on sticking with it👍 i’m thinking it could be a sticky valve at you stated or maybe the decompression possibly malfunctioning.

[@P.Trim69]

Got that same one but it's branded sears companion 10hp 5000watts. Missing the metal air cleaner cover end piece. Great video

[@adamfletcher4262]

Reading a few other comments about camshaft and de compression damage from the tight valve clearance I would be leaning towards checking that I really respect how much time you put into thiese old engine sits great to see so much effort put into making them run great again ! Brilliant video love the real in depth trouble shooting videos it's easy to watch for 2 hours plus ! Keep up the great work

[@johncourtneidge]

Yes!

[@4richardatkins]

Thank you for a really absorbing evening's entertainment. Puts my last few weeks trying to cure a 30 year-old Farymann diesel into perspective!

[@richardcook9738]

Nice job James! You are bringing all of us together with thinking caps on. Several things come to mind because the engine does seem to run better cold. First, fuel boiling in the carb bowl (winter gasoline can and will make this worse). Second, the exhaust valve sticking or compression release malfunctioning. Third, pre-ignition reducing the spark plug heat range. If I know you from all your videos, you don't give up unless there is an obvious flaw. I do recall more than one person installing a 8HP Tecumseh from a junk snowblower (the engines all ran great in the winter) on a log splitter which all ran like crap on the log splitter. (seem to run lean and back-fire when hot)

[@gordiehattrick]

Jim, you were fighting the Tecumseh legacy... There is a reason they are no longer in business. Every piece of power equipment I have owned with a Tecumseh engine gave me problems. You have the patience of a saint, I would have chucked this into the scrap pile after an hour trying to fix it. BTW, I had a good laugh at the multi-meter you use, I have the exact same model 🙂 Absolutely enjoy your video format and production!!! Great work, bravo!!!

[@watermanone7567]

HI Jim: I had some of those Coleman gen sets years ago that had a rear rotor bearing failure. Sometimes they were covered in warrantee. As far as the engine goes, some of the Tecumseh engines don't run to great until under load. Maybe a better spring on the governor might help stableize the engine better. Thanks for a great video.

[@tlgreer1]

The reason you need to run with choke on on your original carb , was due to bad placement of the float bowl when you put it back together,you didn’t Aline the float to the drop in the bowl at recessed place , so in turn it wasn’t allowing the float to drop far enough to allow proper fuel flow thru the needle valve into the float bowl at higher speeds, and which caused the need for the choke usage. Also the value lash problem didn’t help it as well but you took care of that part. Just thought I let ya know what I noticed when you reinstalled the float bowl on the first carb after cleaning it :-)

[@johnplump3760]

Always enjoy your diagnosis and progress on repair of small engines. Over the years, I have worked in mine and my neighbors. Managed to keep them going. Your videos have sure helped. Very good tips. Thanks

[@johncourtneidge]

Yes!

[@mostwanted33986]

Hi james.great video as always, I’m actually leaning towards the compression release tap on the camshaft, in some cases when the exhaust valve clearance is too tight that can cause the tap on the camshaft to bend and consequently causing afterfire from the exhaust. Hopefully it will be easier then that and Good luck 🍀

[@joewilliams5519]

James … have you ever used a sledgehammer on a project like this?

[@jesterr7133]

That is a good idea. It would explain the odd leakdown.

[@martin4787]

At 1:02:42 James, you show a shot of the valve seats and what I can see is, what looks like the exhaust valve seat is oval shaped. When you tried grinding it in, the valve was still bottoming out on the follower. You should have taken some of the stem before attempting to grind it. What I think is happening is the gasses are are getting under the valve and lifting the valve when it's running, but not when you're doing the compression and leak down tests.

[@Sev_Auk]

I agree. Martin's idea is worth a shot.

[@jcondon1]

You are absolutely correct. Cannot believe I did that out of order. Also as you mentioned the seat did look a little off.

[@barthanes1]

Yes, definitely sounds plausible.

[@martin4787]

@@barthanes1 If the rings were leaking, you'd see the gases passing the rings coming out of the breather Bert. Also, you see a flame coming from the exhaust every so often which is the other clue.

[@martin4787]

@@jcondon1 Correct that seat James and I think that'll fix it. 🙂

[@livingsurvival]

I have a small engine business and have been binge watching your channel. One thing I never see you address is the spark arrestors. I find especially on suitcase generators they can cause a lot of little issues. I usually just hit them with a torch. Otherwise love the attention to detail and clear explanations.

[@jcondon1]

Normally not an issue. But have seen a couple.

[@livingsurvival]

@@jcondon1 the newer wen and ryobi tend to clog up quick.

[@TerryLawrence001]

Thanks for all your efforts and these long videos. I like all of your content and especially love the thorough analysis and well done video quality.

[@johncourtneidge]

Yes!

[@williambradford1467]

Great video; even at 2+ hours I was disappointed when it ended. No video of yours is ever too long. I've seen some comments below (and you've mentioned the same in other videos) that you may want to at least rule out the "missing" air cleaner assembly as a contributor during testing. It's plausible, although the symptoms are more erratic than I would expect for that condition. I'm restoring a 20-year-old 8HP Tecumseh-powered chipper, which is presently 100% disassembled in a box. This video provided lots of tips, and I'm looking forward to your next video on this project as further help as I work to rebuild my own.

[@davidbgraham461]

Nice to see you using the adjustable wrench in to correct way. I suspect that not too many people understand the stresses on such tools.. Love you work and, admire your skills.

[@norseman3303]

James, I usually watch your channel on my television, but that prevents me from commenting so I'm using my laptop. Just wanted to thank you for putting so much time and effort into your videos. I typically do my own small engine work, but I have learned so much from watching your videos. I can't thank you enough. I have even upgraded a few of my tools after watching. Thank you again for such detailed and complete videos showing diagnosis and repair!

[@jcondon1]

Thanks for the positive feedback. I appreciate it.

[@Skynet-1]

I think this is the second time one didn't turn out like you hoped (yet). The other one was your buddy's whole house generator that was a no go. I like watching your thought process on these. Fine line on how much money and time you want to throw at this one. Good luck!

[@jeffclark2725]

Well said, i have had several of these projects come through, and when your done, can you get the investment back ot of it, and it last more than a couple years, great video, there are alot of these engines out there

[@philliphall5198]

No big deal just shim the valve springs with.005/.010 shims Fixed it. New spring are to weak to

[@michaelkennedy2528]

@@philliphall5198 .005 to .0010 might be just a tad much, but as i mentioned earlier, it usually only takes about .003 to get it spot on, otherwise you may run into spring bind.

[@LORFCASTER]

With this type of content, the longer the video the better to be honest. Sure seventy hours would be too much, but 1, 2, 2.3, even 3h ish for this kind of content just feels right.

[@Jim-ie6uf]

I thoroughly enjoyed the video. Fortunately for me, I’m home with pneumonia and have the the time . I’m at a loss as well as to the problem. Please do another update video, all your subs are waiting breathlessly for it, none more than me. Pun intended 😀

[@etusuku8848]

Yea, me too, just at home having some fever, but can't sleep until Tecumseh final episode.

[@brianwood5220]

Real great effort on your part here James. The length of time a video lasts is not an issue. In fact with a shorter one I'm wishing they were longer. I thank you for all your content however it comes to us.

[@johncourtneidge]

Yes!

[@ecc1944]

I have been watching your videos for a while. This one I really enjoyed. What a great lesson in testing all that you thought possible only to find a bad crimp. GREAT WORK. I was Chief engineer for our Volunteer Fire Dept. Besides the various diesel trucks, It was always me who was called on to fix the small engine troubles. I always told everyone that they made me chief engineer because I had more tools than anyone else!!! You do an excellent job with your videos and I always make time for a James Condon video! Wow I should have made no comment until watching to the end. I thought you had it with the crimp. My guess (underline guess), would be a tear down and you will find a problem with the rings????

[@BigDaddy_MRI]

Well James, If I were to guess, I would think that no-load, the compression release is causing the exhaust valve to pop just a few thousands. But put the engine under load, the compression release is not actually trying to cause the valve to pop any at all. Crankcase pressure? I don't know, the release mechanism is probably centrifugal and speed actuated. Unless it is broken, or a bit damaged, that is out the window. Otherwise, I would re-ring the engine and gently hone the cylinder, give it a good cross-hatch and stop. Then break in the engine carefully, and see if the problem is fixed. I don't think it is spark, although, I would buy a new spark plug, because I had a 5 horse Briggs lawnmower that ran like crap and it was about a year old. I did everything except tear it down, and finally replaced the plug. And then it didn't run at all. So, I bought another plug, and the thing fired up and we are still using the mower today about 8 years later. So, don't trust new plugs, or maybe I'm one out of 100,000 that just got a bad one. But the second plug fixed the original problem. Looking forward to the second video. Thanks James for great video content. Take care.

[@wildefox1478]

Great video, excellent troubleshooting and testing as always, pretty strange issue with that engine. Hopefully you get it figured out, nice work James!

[@bubba6945]

id suspect weak valve spring being the issue

[@brad6551]

I love the way you grow an extra set of arms at critical moments

[@jesterr7133]

This was an interesting video. I had to wait until I had enough time to pay close attention, but I don't mind long videos at all when you are dealing with an unusual issue that doesn't have an obvious solution. I love learning new ways to troubleshoot. That is my weak point, so I love stuff like this.

[@SgtGoogleDad]

Still could be the coil wire itself. As the coil wire heats up it can become a resistor ie hotter the engine hotter the wire as temperature goes up so does the resistance. So cold engine coil wire seems fine but once at run temperature the resistance in the coil wire or even the coil it self can increase to a value above the documented tolerance. Kinda rare but does happen and is one of the most missed causes for a misfire that I have run into on customer self diagnosed issue. Hope your having a great day James haven't chimed on for awhile so figured I'd throw my 2 cents in for what it's worth.... just because it looks good doesn't mean it is good. Even when you get a good reading. Must remeber test values change within engine temperatures. Figured it it's an appropriate reminder that sorta fits in with this diagnosis. Love your videos and the just pure diagnostic patterns you follow. So clean and very rarely do you get into the weedes. You are a master at small engineering repairs. This coming from a 30 ish years master tech. You know your stuff forwards backwards upside down and blindfolded so rare anything gets by you. It almost feels like watch sports and your my team that I'm cheering for. Keep it up. Thanks for the great info.

[@dquick282]

Hi James, Been awhile since I last commented but after watching this video I regret it. I’ve said it before but I love your troubleshooting methodology. You got to a point where you had to walk away and think about it. I appreciate your thoughts. Proper troubleshooting is not always shotgunning part replacement but actually proper critical analysis. Sometimes you lost and like this example you did replace the coil. I was thinking the same the last 30 mins of the video. I would have done he same thing. I was an aircraft mechanic and leak down checks were very common. I can’t imagine with those results having rings issues. It I’m with you. What else could it be? It’s quite exciting for me to see your struggles so sorry I’m getting satisfaction on your troubles but Troubleshooting is my favorite part. I’m definitely living vicariously through you. Me personally these longer videos are better for me. Don’t worry too much about going too long. I appreciate you trying but still showing quick content what you did off screen. Love this channel. Thanks for doing great work and holding an excellent standard. Hope all is well and please keep the content rolling.

[@thepubliceye]

james has been doing so much for so long with so little, that he is now qualified to do anything with nothing

[@billhenry7833]

Looks like he has plenty of tools to me

[@ronaldbrown5745]

For ever!

[@ebertilaar2271]

​@billhenry7833

[@BruceBoschek]

😂

[@pantherpaw9]

You’re an excellent mechanic. Great determination sir! I would have been loading a brand new generator in my truck at Home Depot long ago 😂

[@Amy_McFarland]

Ha ha, I saw your black kitty sneak on by just b4 the valve cleaning...like maybe he won't notice...lol

[@onepeanutwhistle5232]

Are any of us going to suggest a “cat” scan now?

[@Amy_McFarland]

@@onepeanutwhistle5232 You just did! 🤣😂🤣

[@myusernameisrighther]

@@onepeanutwhistle5232I’m still waiting on the Lab results.

[@markthehunter4885]

I try not to like you but you went through this engine with a fine tooth comb. you left no stone unturned and had me on the edge of my seat throughout the whole video. this is one for the books as this engine may be possessed so I'm glad you have a video of the diagnostics. "the little engine that could" is very good at hiding a small secret, my hat is off to you. if you do uncover it I would sure like to know.

[@seastacker8582]

We had that same generator. It was ungodly loud. We bought that same muffler to try and quiet it down. It’s been years, but I seem to recall it was a Tecumseh part/ kit.

[@WrigleyFieldBlues]

Your patience is phenomenal! I'd have taken a sledge hammer to that engine by now (joking, not really... although I'd have liked to). My Dad had a snow blower with a Tecumseh engine on it. We struggled with trying to get it running good for years. It's actually comforting to see that even the experts can't always get to the bottom of things with this engine. After all your effort I hope to see a follow up on this one explaining the magic formula. Seems like you've already had some good suggestions here.

[@WACKO1123]

Perhaps an oscilloscope on the sparkplug could reveal a fluctuating spark pulse as well as it's voltage. Only idea I have. Great video.

[@v-g-z3689]

Should have thought of that... very good idea actually! An oscilloscope usually finds an ignition related problem within seconds... we do it on cars all the time cause the customer obviously dosn´t want to pay for hours of troubleshooting. Why not use it on a small engine!

[@mjg263]

I have the same basic Tecumseh engine on my snowblower (just the winterized “Snow King” version) and it runs exactly like that. Pops and misses a little when sitting with no load, but runs smooth when it gets down to business under a load. Tried everything in the book and never could get it to smooth out under no-load conditions, and I’ve been working on small engines since they still had points!

[@chubbyadler3276]

I don't remember ever having an older engine of that sort from the 1980s and 1990s that ran absolutely perfectly, so what you have at 1:39 seems normal.

[@baileyhatfield4273]

Know anything about a lawn tractor/gardin mower engine 13.5 Briggs that pops? Starts perfect, carb been cleaned, new plug, good gap on the coil, valves lapped and lash done up. Runs i'd say flawlessly, besides the pop. Makes me feel like a redneck (might be) for having a machine that just doesn't sound good.

[@chubbyadler3276]

@@baileyhatfield4273 I think this may be partly what this one is about, and like I said, all the older 1980s and 1990s Brings and Tecumseh motors I have been around miss every couple of seconds, especially at no load. It may just be the nature of the beast.

[@benjamincresswell3713]

​@@chubbyadler3276 No it's not. I have never allowed an internal combustion engine to run with a misfire. I've always fixed it. For Jim, the question is at what cost. If you had the right tools you could see what's making it misfire. It's not rings, not valves, not timing, not A/F ratio, it is electrical. Somewhere the spark is being diverted. Could be as simple as a bad spark plug(s), or low tension side intermittently shorting. But I'd put my money on a bad ignition coil right out of the box. That breakerless ignition has some sensitive electronics inside it, ie: a couple of NPN transistors, and there might be your dinner. If Jim knows someone with a scope, they could look at the spark quality and see it breaking up. Trust me, I worked in precision engine tuning at GM for 36yrs w/ the EPA breathing right down my neck. Try tuning a DOHC 4 valve/ cyl with variable cam timing, duel fuel injectors and modulated EGR. If we couldn't "tune it," we couldn't certify it, and that means we couldn't sell it. If it really matters to know, you have to have the tools to find it or keep replacing parts until you hit it. I hope Jim finds it and lets us know. bc

[@chubbyadler3276]

@@benjamincresswell3713 They must have sold them new with defective coils back then, because every one I ever had did it. That's not to say there wasn't another issue that affected them all, such as the fuel I had available over the years, but it would have to be something whacky like that.

[@craignelsen3740]

i have a couple tecumish 10's. i'll be saving this video in the event that i need to revert back for instruction if either shows the symptoms. ty for this wonderful video

[@keithbeaty3292]

Hi James, another great episode. I like the long videos, watch it over a few nights. My soon to be five year old boy loves watching too with a question every five seconds. Was raising the tank an option and extending the heatshield with a piece of sheet metal? I think I would have tried that. Thanks for all your great work 👍

[@Farm_fab]

Just finished up another generator, Jim. I replaced the gas tank with the missing threaded cap for one from a HF generator, and the tank was a direct bolt up. It started easily, but produced no power. I removed the brush holder, checked the rectifier, and replaced the electric outlet. I then started the engine and checked the output on the back of the generator, and it was outputting 128v. I still have to test to see how close it is to 60 Hz, but that's another day. I have a clamp meter which has a frequency setting, so it won't be hard to adjust. Since I use the generator on an Amish farm, I'll make a dolly to roll it around, but it will only fit that generator.

[@adnacraigo6590]

I can only think of two things. One has to do with the coil breaking down or grounding issues with the coil. The other one could be a defect in the casting or a slight crack in that aluminum mount for the carburetor that could be leaking vaccuum.

[@johncourtneidge]

Yes, a minute hole in that pipe might be it.

[@robertfountain4856]

A small engine shop would never gone as far as you did with this engine but I do like your low pressure leakdown percentage jump result. • The only thing you didn't consider is if the engine didn't like those White Wheels. • Why is it fighting being started??????? I'm pleased to see you check the intake manifold. • I'd sell it as is at a reduced price with a love note saying that it runs well under load.

[@paulperkins920]

I wonder if a higher octane fuel would solve the issue. Like it isn’t missing but pre-ignition of the fuel charge. Hope you get it going. Thanks for the videos

[@brucepickess8097]

Pre ignition is called "pinking" and you can audibly hear that. I'me sure that he would have heard that.

[@RS-yj3gn]

I'm sitting at 6am watching with interest this fantastic video of yours! Thank you so much for teaching us to be calm ,rational and patient and so much about all types of small engines and generators. But I have to admit given the number of nagging issues I would have lost my cool on several of occasions..... Recently I bought a new Opo mobile for about 400, - bucks, in three days I could not get the software to work for me.... So Opo flew against the wall. Feel better now!

[@SgtGoogleDad]

Hey James, love your videos, keep up the good work. In reference to what your seeing. At high pressure / low pressure . I've seen something similar to this. What may be happening is when you apply high pressure it's forcing oil from the crank case up into the ringe causing a hydrostatic seal. Which approximates the appearance of a good reading on leak down etc. But it's actually oil being forced up the cylinder walls creating a hydrostatic seal. Hence the higher than normal compression. The only seen this a couple of times in over 25 years working on engines etc. Happens both hot and cold, cold reading will be just a bit higher than hot. The pressure will be slightly high with a cold engine and drop slightly on a hot one. It basicly reverse blowby. Is there a breather tube or something similar on this engine. If so check to see if it's blocked or partially blocked. By breather in refering the crank case breather being blocked or partially blocked the worse the blockage the higher the compression will be. The clue is the higher than normal compression of 70 in stead of the 60 you normally see. Super rare but will bet dimes to dollars you'll find the issue in that area. Hope this helps. Easy way to test for it is do a compression test with the oil fill plug 1 installed or ie in place.,2. With the oil fill plug removed. Remove the engine compression will drop if this is the issue.

[@Haffmatthew]

I really enjoy your videos, man! I’m a novice at small engine repair and so watching your content feels like I’m being familiarized with the basics and offers me a wide amount of foundational information to then use when I’m tinkering on my own projects.

[@jongerber3476]

I sure am glad you got a lift. We are not getting any younger. Wish I could have had one working on bikes for all those years. Thanks for posting.

[@michaelkennedy2528]

Wow, getting old school there. Almost in line with a Model T lol

[@jfjjjjfj]

Mabye it's the rings that are half stuck, as you mentioned. Run it for a while with a syntethic oil with good cleaning ability, to free up the rings. Otherwise check the camshaft. I repaired a B&S 12 hp mover before wich had a bent camshaft. The valve clearance was good at TDC. But the engine refused to rev up over 1000 rpm. I then checked the valves when turning the engine over slowly, and saw a suspicious movement. The camshaft must have got bad when the engine throwed the rod. The rod was replaced and it never run good after that. They had the mover to 2-3 repair shops, but no one could find the issue. I love your videos, it's so satisfying to watch. And you work just like me, calm and with a torque wrench 🙂 Cute cat 🙂

[@johnporter2804]

The big clue here is it got worse with a new plug A stronger spark could produce a higher pressure on the power stroke because of better fuel combustion which could aggravate a problem with the valves having a weak spring and bouncing when closing I have read all the comments and concluded valve spring pressure is the most probable cause according to popular opinion I’ve never seen a new plug make things worse in any engine! That’s very unusual! ( just saying) 😀

[@JernD]

I wonder if the gap size was the same between the old and new plugs too

[@bigrickyricks]

Valves bouncing when closing?! I never would’ve considered something like that. Hopefully, whoever was the first to diagnose that got a medal

[@JugSouthgate]

Great job and video - as usual. Just one thing I would have done differently. I would have made a new flat heat shield from a flat piece of sheet metal, and raised the tank on brackets above it. That way the spark plug could be serviced without removing the tank or heat shield. Just personal preference.

[@GGigabiteM]

One thing you didn't do for most of the testing is have the air cleaner on. The air cleaner creates enough drag to affect the mixture, possibly making it too rich. You may try retuning the carb with the air filter installed, because it can change how the engine runs significantly.

[@brianallen9810]

Your probably right, especially with Tecumseh engines. There's a reason Tecumseh went out of business, those Chinese Honda knockoffs are assembled with far more quality.

[@Farm_fab]

@@brianallen9810 they didn't go out of business. They were acquired by an investment firm, and still manufacturing parts, and have a number of engines in stock. Better check Project Farm from last week on YT before you think they are better than Tecumseh. One they tested used almost half of the engine oil on a 24 hour test. They also produce more carbon monoxide than the Honda engine in the same test. The predator engine was a little bit better, but not better than the Honda engine.

[@littledave601]

@@brianallen9810 I'd have to agree on Tecumseh engines, I've never personally seen one that ran correct. My dad has this exact generator and it has never ran smooth. There was a old guy in my town that had a old rear engine John Deere mower with a Tecumseh engine and he constantly fought it for years. One day he pulled up to his house and idled it down and it threw the rod out of the block. I went to our local scrap yard and got a 8 HP Briggs and stratton and put on it. He said he just didn't know what to do with all of his time since he could just go and mow and not have to adjust the carburetor on the Tecumseh. It was still running when he passed away years later.

[@billyjackson5799]

@@littledave601 yeah Tecumseh motors are good for either pouring oil like a siv wanting to run pretty much wide open no matter how you try to tune them or they will randomly chuck the rod out the side without any warning what so ever every one I have delt with has been like that so when get something and it has one of those on it the first thing I do is pull it and send it to the scrap yard and replace it with a good old briggs

[@GIGABACHI]

That's a good possibility, on motorcycles it happens more than people would like to admit. Same on some GM vehicles with the MAF sensor built into the air filter housing. No filter, bunch of weird A/F related codes.

[@allanarndt3047]

I like watching your thought proses but wondered if you could have just moved the control panel to the front side of the square tubing,this would have given you room for the tank. All you would have had to do was rivet a 2-3” strip of sheet metal to extend the heat shield. Your fix did work but looked like you made extra work? Maybe you could see something I couldn’t in the video which might have been in the way? Just a thought?

[@douglasthompson2740]

PS: Look between the laminates on the old coil pickup arms. Often you will see minute rust jacking the laminates apart. Again weaker field bit less spark. I also wipe a bit of ignition rated silicone grease on the flywheel perimeter, just a bit. Just a hint to hold back the corrosion, especially in a wet application or one that lives outside. I have also seen the coil plug wire have a break in the conductor which after heating up will open up. Inside the insulation so that it isn't visible until you slit the wire for an autopsy.

[@Jaxter1137]

Great video. Well worth the time watching. I love the fact that you also show the links too the stuff you use during the project. Thanks

[@jamesdougan8789]

g`day james i am going to take a guess at a sticking cam follower or valve guide because as you showed something closes at low pressure on the leakdown test as pressure rises and overcomes it and when the engine is running and getting hotter it may be floating the valve (sticking for a moment) . as a flame came out the exhaust i will take a guess on the exhaust side is leaking the air i also thought the decompresser might be sticking hope you do the follow up video to see who guessed right lol.. i like the longer video format great video james cheers

[@wisemannhlakaniphobhengu2285]

James you've done everything we think can cause that ,hope on your next we'll learn how to troubleshoot the problem and will help us learn (South Africa)

[@gregdawson1909]

I'm thinking you might have an issue with the cam folowers / lifters, if ones a little sticky under light load it could be hanging up and causing the problem it would explain why it seems better when cold, but when it gets hot it starts hanging up..

[@jcondon1]

Good point.

[@WayneTheSeine]

This came back up in my recommendations so I watched it again. At the end when you are going through the list of things you tried you mentioned you changed the coil...I did not see it changed. Maybe I missed it. (see you replaced it at the very end of the video) That being said, a shade tree hack we used to use on our outboards to test the coils on a rough running engine, was to spray each coil down with WD-40. A bad coil with micro cracks would temporaily functioin properly and the engine would smoot right out. It didn't last long but you could quickly diagnose which coil of the four needed replacing. Work like a charm.