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Discussion Starter · #1 ·
Hi guys-

My 10515 has alot of hours, a heavily scored piston, leaking seals (top and bottom), but runs great with 121lbs of compression. It needs to be primed 5-6 times to get it to start.

a few days ago it started quitting randomly. It also starts back up,but seems to need to be primed in order to re-start. then it runs great again with lots of power for another 15-20m or so. If I had to say anything I would say it seems to run lean. Carb it clean as a whistle, and is a typical LB plastic carb with a priming bulb only.

Is this a symptom that my seals are finally gone?
 

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Hello 4running.

Yes, this is a classic motor with a classic symptom. As the seals finally go, the piston cannot create enough pressure in the crankcase as it falls, and also cannot pull enough vacuum through the carburetor as it rises. It's not that the seals leak fluid out, but that they leak air. I suppose it won't be long before your mower won't start at all. The good news is that these are fairly easy to work on.

I hope this helps,
HDNewf.
 

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Discussion Starter · #3 ·
Yeah, I think your right. The lean condition, is really a symptom of these seals leaking. I order a set and get them installed. This is a great machine, and I am not willing to give it up over some seals.
 

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But, was not the compression at 121 ?
I agree with the seals, nevertheless.
Also, the cleaning of the exhaust at the same time the seals are done.
I think that this is definitely what my 7229 needs (bushings and of course seals).
I was never a well trained mechanic, had to do it all via OJT...this has limitations..
 

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But, was not the compression at 121 ?
...
Yes, you can have good rings and bad crankshaft seals. Cylinder pressure will be good, but 2 cycle engines also need to pressurize/scavenge the crank case. The bad seals leak air that disrupts 2 things:

1. As the piston moves up it creates a vacuum inside the crank case which is used to pull the fuel mixture from the carb.

2. As the piston moves down it creates pressure inside the crank case which is what charges the cylinder with that fuel mixture through the intake ports.

As the leaks in the crank case get worse, the end result is leaner and leaner fuel mixtures and rough running. Eventually the engine will not run at all, even with high compression from the piston rings.

I hope this helps,
HDNewf.

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