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Showing results for tags 'onan p220g_lost compression'.
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Finally had some time while it did nothing but snow today to open up the Onan that was on my 520-H Loader tractor. This is a continuation from when I swapped out a spare P220 because of only 30PSI of rear cyl compression on the original engine. Long story short......the first owner of the tractor had the original motor's rear cyl intake valve seat repaired not once but twice to where it is now .030 over. (You will see that easily from the pics of the front to rear cylinder). I didn't even put 500 hours on this motor as the third owner and it is really carboned up but the valve seat and valves look pretty good. It's using some oil but from what I could tell, the valve isn't the main culprit in the loss of compression. I'll know more when I get to the tappets. Looking around the heads and the gasket, it doesn't look like it was leaking around the head. I'll know more later this week when I get the intake off of it and adjust the valves. Again, it was in real need of a decarbon job! First pic is the front cyl. Next two are the rear cylinder with the close up of the over-sized valve.
