Tecumpise Problem

[jacko]

I recently inherited a lawn mower with a 3.5 Tecumseh 4 stroke. I tried to start it and it kicked back hard. First time it busted the pull cord. Second time it nearly pulled my finger off. I was sure that the flywheel key was sheared off and the timing was off, but I checked that and that's not it. I reset the air gap on the coil and still the same. I did get it to start a couple of times and it runs great . Shut it off and try to restart and the dam thing kicks back and yanks the pull cord out of my hand violently. Any suggestions?

[Oren]

I would pull the tappet cover off and see it the valves are working, and not *sticking*. Weak valve spring?

-- Oren

"I didn?t say it was your fault, I said I was blaming you."

[David Martel]

jacko,

Are you sure that the correct sparkplug is installed and that it is correctly gapped?

Dave M.

[Meat Plow]

Is the shear key bent at all, the keyway worn? Flywheel move?

[pheeh.zero]

It does sound out-of-time (sheared key). As I recall...different models have their own color-coded flywheel key. Could this have the wrong key for that model? Also, with the light-weight flywheels...it is important to have the blade tight (and some blade adapters can shear)

[Harry K]

Check the flywheel key again. I had one that was doing what you describe. On second inspection I found that the key was slightly indented. It doesn't take much to throw the timing off.

Harry K

[jacko]

Following the comments I received, I did some re-checking. I pulled the flywheel again and inspected the key and keyway. Both were in good shape. I pulled the head and cleaned away a little carbon. The valves were working well. I changed the spark plug to insure the correct one and gapped it. I reassembled and attempted to start it. The thing kicked back and left me with a very sore finger. While I had the head off, I noted a score in the cylinder wall. Not really deep. I can't imagine what this might do to cause the symptoms I have. I'm baffled.

[DanG]

I think I'm telling you right. Tecumseh has different keys that advance different amounts. You must have the model number of your motor to make sure you have the correct key.

[jacko]

You are right of course. The problem that I have, started suddenly. This mower was being started and used by a kid. It was used earlier this year. No one had the flywheel off before me.Also there are no markings on the motor or mower bed which makes it difficult to identify the model. I suspect it is destined for the parts box.

[DanG]

[jacko]

Dan G. Thank you very much for your help. I just went to my shed and the number was right where it said it was on that site. It's worth a try to pick up the right key. I'll try that when the dealer opens on Monday and I'll post the results.

[Don Young]

You aren't possibly trying to start it without the blade attached, are you? Most mowers with a directly attached blade only have a lightweight flywheel and depend on the blade to provide enough flywheel action for the engine to start without kicking back.

Some engines also have some form of compression release to help starting. Some engines lift one of the valves slightly open and too much valve clearance will defeat this and make it hard to turn over and also kick back.

Don't know if any of this applies to your case.

Don Young

[Oren]

Quick lesson! A scared cylinder will damage the rings!! A burr in the cylinder can affect the ring(s). Without that scenario, the rings can aligned and you have issues.

-- Oren

"I don't have anything against work. I just figure, why deprive somebody who really loves it."

[jJim McLaughlin]

Nice reference, thanks for the cite to the site.

[jacko]

[pheeh.zero]

Previous post: It does sound out-of-time (sheared key). As I recall...different models have their own color-coded flywheel key. Could this have the wrong key for that model? [[Also, with the light-weight flywheels...it is important to have the blade tight (and some blade adapters can shear)]]

Is anyone paying attention...or am I in your killfile?

[Harry K]

really loves it."

True but the 'issues' will be loss of compression to some degree plus oil consumption. It will not cause his problem.

Harry K

[dpb]

Oren wrote: ...

I hurt things (often one them being me) when I'm scared, too... :)

--

[Meat Plow]

Well for crying out loud, why didn't you mention that in the first place??????

[Meat Plow]

No kidding.