Tecumseh help

[Iggy]

replying to trader_4, Iggy wrote: Walk away, he's not checking anything and just keeps trying the same thing, expecting it to fix itself.

[Steve Kraus]

Yeah, since posting I found a photo of the off-center T shaped key.

Sort of. I do not own a gauge; I will have to decide if one is worth buying for this. I do feel it on my finger if I place it on the spark plug hole not to mention hearing it wheeze at the exhaust. (Muffler is off for now.) And it's harder to turn with the

Let's say the compression is bad. Would that prevent it from running at all (as opposed to running badly or weakly)? What would be the likely cause? Broken ring? Now that I think about it, when I had the head off the cylinder did have some scuffs.

[My 2 Cents]

Neighbor bought a used mower from a friend and the air cleaner hold down was cross threaded... long story short the cylinder was scuffed and ruined. I got it to run but just barely. With yours I'd be checking that and the valve clearance and I once had a lawnboy the old 2 cycle type.. had spark and would fire and and sometimes run... I finally notice a spark jump from the back of the coil to ground.. the coil was cracked and the plug would fire when out of the mower but not under compression. So you might try a really wide gapped spark plug to test for something like that. Briggs makes a spark tester if you want to spend a few bucks. Also make sure the tank is vented properly or drill a small hole in the cap. Intake manifold gaskets... blah blah blah. When all else fails try one of these Predator engines from Harbor Fright.

... wait till they are sale or use the coupons they always have. Happy mowing !

[Steve Kraus]

This morning I tried fingering the spark plug hole on the other mower with a T engine and not sure I can tell the difference. What was the deal with "compression release" that they used to advertise as making starting easier? Maybe it was only on Sears Craftsman mowers with T engines. Whatever it was, isn't it going to make it harder detect issues?

Unless it really is just a weak spark (jury still out on that), the carb & gas issues would have been addressed in testing with fuel shot in (the mix would have been correct at some point) so that just leaves a severe mechanical issue of some sort and likely not worth fixing.

I'm nearing the point where I'm going to give up. I would then dismantle the engine just to see what's what. There is actually an extensive Youtube video series where my exact engine is dismantled and reassembled. That's probably too much trouble and/or maybe beyond my abilities. But dismantling as a learning exercise before pitching the metal into recycling sure, may as well.

[trader_4]

That is what it is and you raise a good point. How do you test for compression on an engine that has compression release? If you can get your hand over the carb intake or intake manifold with the carb off, you could test for suction. Not sure how probative that is though, ie how you judge how much should really be there by hand.

I guess the compression release thing brings up another point, which is that to get the engine started, it apparently will start very readily with a substantial decrease in compression. If it didn't compression release would not work.

I'm not so sure about the fuel mix being right at some point if you spray ether or fuel into the carb. It would have a high probability of being right enough to fire at some point. But on the other hand, I have seen cases where I sprayed it into a carb on a mower and it still would not fire. If it's flooded for example, you would flood it more and might not clear it enough to get it to fire while pulling X times, etc. But those, I've left alone or left the plug out overnight and next day it started.

I had good results with my two cycle leaf blower. It had a gunked up and stuck piston ring. I took it apart, cleaned it up, with that and the new $16 Chinese carb, it's running better than ever. This thing went from running great after I put the new carb on, to not starting at all next time I tried to use it. Given that, compression was not even on my list, because I wouldn't think it could go from running full blast to suddenly not starting due to that. But I guess if the piston ring is getting fouled, eventually it gets to a point where it sticks and then suddenly it's kaput.

[My 2 Cents]

The old style Briggs and Stratton held the intake open just a bit all the time (they usually had "easy spin" on the recoil starter).. newer engines most all of them use a centrifugal fling out thing on the camshaft the keeps the valve open just a wee bit till it's up to speed. One of the reasons you can't check compression on the small engines. Is this overhead valve? If so it's really easy to adjust the valves but go by the book, on some you have to turn the engine a 1/4 way past TDC so the compression release doesn't give you a false reading. Also it's rare but a loose blade will give you hell, it acts as the flywheel and if it's lose the engine will pop but not run. Spark plugs can be misleading with small engines, they look good but try one from a known running engine. I use a shot of carb cleaner to get the little engines to start easy. If you get the word out you'll get lots of free non running mowers to play with. Folks just go buy a new one when they quit and put the old one out by the curb. What can you do with one of the old engines you get running? Here one thing...

[Steve Kraus]

Interesting development just now.

All along I felt that whatever experiment or test I was trying in an effort to get this thing going would be that much more likely to succeed with more vigorous cranking, more than I can manage by hand.

This engine does have a 12V electric starter which runs off a battery one keeps charged with an external charger. I have not used it in years because the plastic ring gear on the periphery of the flywheel is chewed up so I don't even keep a battery installed. So among my experments I tried hooking it up to my car's battery and hoped that there would be sufficient momentum to get past the bad parts of the gear but that was not this case.

This morning as I still had the shroud off to look at the flywheel key I thought I might take advantage of the exposed crankshaft top. I tried cranking it with an air wrench but it was not fast enough.

So, after rounding up the appropriate adaptors, tried again with an electric drill. (After the usual shooting some gas into the carb with a syringe.) I thought it was a lost cause but what the hell, after some lengthy cranking the engine started to run. Not great...a lot of missing but it did run. I killed it after a minute as I didn't want it to overheat without the shroud guiding the air over the cylinder.

I quickly bolted the shroud on and it cranked up with the recoil starter okay and I put it to the test picking up leaves. I don't know anything else as I was pretty convinced there was a broken ring or some other internal calamity. Of course the real test will be starting it cold.

But there you have it. A Festivus miracle!

[trader_4]

Good to see it's working. That's why I told you that I had similar experiences once in awhile, where you'd think it should fire with ether, etc, but it would not and just letting it sit for a day with the plug out, then trying again, it started. I would suspect yours and mine were simply flooded and it's not as easy to get the right mixture level in there under all cases as you might think. Hope it keeps going, I'm off to blow leaves, see if that sucker still starts OK.....

[Clare Snyder]

If the compression is low it won't start well. If you are hearing it "wheeze" at the exhaust port I'd say you most loikely have the exhaust valve stuck partly open.

[Clare Snyder]

Put some "top lube" in the gas - something like Marvel Mystery Oil. Some in the oil too - I'm betting you had a stuck exhaust valve and you want to free that up.

[Steve Kraus]

I cannot rule anything out at this point but I did have the head off at one point and valves seemed okay. They cannot stick closed, right, only open?

One thing I totally forgot about was there was a time when I yanked the cord and it just seemed to lock up. I pulled the plug wire and turned it backwards a bit and then it was okay. Liquid locked? Yes, maybe but who knows? Up until this morning I was thinking that was further evidence of some serious internal mechanical issue.

It could be a combination of things. Poor carb, air leaking into the suction, poor compression, weak spark. Faster cranking might get around all of them. We shall see.

[trader_4]

One thing not asked in all this is how much service has this mower seen?

Meanwhile my leaf blower is still working better than ever. Blew off most of the yard, went through two tanks of gas now. I'm behind on leaves this year because of waiting for the carb and all the repair drama. But then so too are the leaves because of warm weather. I'd say we're at least two weeks behind here in NYC area.

[Steve Kraus]

It was a gift for my (since passed) mom in May 2006, a Lawn Boy 10686. I liked the intuitive propulsion (just pushing the spring-loaded handle makes it go, no other control) and the electric starter. She mowed the small front yard by herself into her mid-80's. It's a small fractional acre suburban lot so 11 years of that.

The negatives on this unit: The key starter switch fell apart twice, once under waranty. I eventually replaced it with a pushbutton on a box (containing a relay since the button could not handle the current). And the Molex or similar charger connection with a 12V cigarette lighter type connector.

And though the manual mentions an high lift blade I don't think they were ever made so we were left stuck with a compromise blade. The last mower (which I still have) I removed the original compromise blade and got a lift-only. Far superior if you bag and want to use the mower to suck up leaves & debris. The compromise blade lifts at the sides but blows down in the middle for mulching purposes. I should look into an aftermarket blade.

You can tell the compromise blade because if you approach debris on the driveway it is as apt to blow it away as it is to pull it in. The traditional blade was more like a vaccum cleaner.

This morning I pulled out the mower and followed official procedure with the primer bulb. No start. I shot in a few cc's of gas and pulled the cord and it started and ran. It doesn't sound totally right but it was running just from a hand start. This whole thing is puzzling.

[trader_4]

Did you check to see how much you can get a new carb for on eBay? I found one for my leaf blower for $16. IDK how much you want to throw at it, but that's an option. If you don't keep it, you can put the carb up on eBay an d get most of your money back. Also they have rebuild kits that have new g askets, needle valves, etc for ~$10 for many carbs. If you go that route, check if the carb or kit has the gasket between the carb and intake, that m ay not be included.