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Discussion Starter · #1 ·
Anyone know what would cause low compression other than worn piston rings?

I did a compression check and according to the service manual it should be between 139 - 215 PSI. I am getting 90 PSI on cylinders 1 and 2, 120 PSI on cylinder 3, and 180 PSI on cylinder 4.

I plan to pull the motor apart and change the ring since they are cheap, $40 a set, but I would like to know if any of the valve may contribute to this issue so that I can get it fixed while im in there.

Thanks
 

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Discussion Starter · #3 ·
I did a wet-test afterwards by dumping just a little over 1 tablespoon of oil in cylinders 1 and 2. They both went up from 90 PSI to 140 PSI. From what I have read, this is most likly going to be worn piston ring.

Anyone have any thoughts?

Thanks,
 

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That would indeed follow worn rings. While it would sound pretty likely that you are gonna open the motor up, I'd do a leak down test too.

My compression tester has a standard coupling on the hose to connect it to a gauge, or I can pull the gauge off and hook to an air supply. So while I can't do a true leak down percentage test, I can find the leak path.

Rings could be stuck or cracked too...either would surprise me. Head gasket, valves...all possibilities...but I must agree rings are most likely.

Hopefully the cylinders are ok.

Good luck, and let us know what you find.
 

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While your in there might as well get a valve job, and put some fresh bearings on the rods and crank. Hell maybe even a new chain tensioner. When its all back together get the valves adjusted.
 
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