Questions about tecumseh 5hp compression #s?

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I have a tecumseh 5hp (manufactured 1998) that stalled for an undetectible reason and would not re-start (this is on a craftsmen mower). Once it cooled down it started back up fine. I found some head bolts loose then tightened them. I proceeded to check the compression and found the highest it would go is 92 psi. Anybody know if that is a normal compression reading? Thanks for the Help!
 
I heard the old rule of thumb was anything over 60 lbs of compression was acceptable on a flathead style lawnmower engine. That could be wrong but it's what a close friend that worked on mowers with me always said. Seemed to be somewhat accurate too.
 
Originally Posted By: cknight49090
What is the engine model #?


model # 143.985004
family - stp185u1g1ra
 
Originally Posted By: FFeng7
I heard the old rule of thumb was anything over 60 lbs of compression was acceptable on a flathead style lawnmower engine. That could be wrong but it's what a close friend that worked on mowers with me always said. Seemed to be somewhat accurate too.


thanks! if thats the case i have plenty?

This mower has had a hard life. It mows 2/3 of an acre in the mowing season once a week.
 
If it will stall when warm and won't restart until it has cooled down, that tells me it is a heat related failure. I bet your ignition coil is going bad. I've replaced a few of them on Tecumseh engines that had the same symptoms and that fixed the problem.

Compression sounds okay. It is hard to get a reading on small engines since many of them have a decompression feature that helps make the engine easier to start.
 
Originally Posted By: jeepman3071
If it will stall when warm and won't restart until it has cooled down, that tells me it is a heat related failure. I bet your ignition coil is going bad. I've replaced a few of them on Tecumseh engines that had the same symptoms and that fixed the problem.

Compression sounds okay. It is hard to get a reading on small engines since many of them have a decompression feature that helps make the engine easier to start.



Thanks, I was eyeing the coil also. I do have a spare coil off another tecumseh.
 
Last edited:
Originally Posted By: cknight49090
It should be above 80 but 60 is acceptable as already said.

Thanks!
 
Originally Posted By: caravanmike
This mower has had a hard life. It mows 2/3 of an acre in the mowing season once a week.


It's hard to kill a Tecumseh engine. They usually don't get much love, but they have full pressure lubrication (though no oil filter) and are very easy to service. The most common issue with them is dirt getting into the main carburetor jet. It's a simple job to clean that out, or if it just doesn't run right, get you an Oregon carb off Amazon or eBay for 20 bucks. Parts are easy to find and reasonably priced if you have a local shop who services Tecumsehs.

I will say that I've never had to replace an ignition coil on a Tecumseh engine, but it sure does sound like that's the problem here. You should be able to confirm that by checking spark at the plug immediately after it shuts down. If there's no spark then, but you get spark back when it cools down, it's very likely the ignition coil.
 
Originally Posted By: Hokiefyd
Originally Posted By: caravanmike
This mower has had a hard life. It mows 2/3 of an acre in the mowing season once a week.


It's hard to kill a Tecumseh engine. They usually don't get much love, but they have full pressure lubrication (though no oil filter) and are very easy to service. The most common issue with them is dirt getting into the main carburetor jet. It's a simple job to clean that out, or if it just doesn't run right, get you an Oregon carb off Amazon or eBay for 20 bucks. Parts are easy to find and reasonably priced if you have a local shop who services Tecumsehs.

I will say that I've never had to replace an ignition coil on a Tecumseh engine, but it sure does sound like that's the problem here. You should be able to confirm that by checking spark at the plug immediately after it shuts down. If there's no spark then, but you get spark back when it cools down, it's very likely the ignition coil.
thanks! this is my third tecumseh mower, usually the decks rust out or crack on me. and i end up harvesting the motors for other good decks from neighbors.

but next week when i mow again i will be mowing with my sparkplug socket in my pocket ready to go to check spark, if it stalls again.
 
Might try making the plug gap really close, to help you troubleshoot a failing coil. Sometimes it's easier for the spark to jump a tiny gap.

But, also, don't discount a spark plug issue. Always start with the basics.
 
Originally Posted By: Hokiefyd
I will say that I've never had to replace an ignition coil on a Tecumseh engine, but it sure does sound like that's the problem here.


That makes 2 of us. For the overwhelming weakness of the carburetors of Tecumseh, I've never seen a bad ignition. I own and run a snow thrower with nearly 700 hours on it and I've only replaced the spark plug 2 times. All signs clearly point to a broken wire in the ignition system.
 
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