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General Forums => The Mess Hall => Topic started by: GlacierJim on December 19, 2006, 10:28:30 PM

Title: Compression Check Range?
Post by: GlacierJim on December 19, 2006, 10:28:30 PM

Looking at buying a motor with the miles unknown. They have run a compression check on it and I was told the following:

"MOTOR WITH 140-150 ON THE COMPRESSION, 25 PSI ON THE OIL PRESSER"

Can someone give me a link to show on a graph where this motor stands? Or give me some idea of what the normal compression range is @ with 25psi of oil presser?

This is for a 1995 YJ 2.5L

Thanks,

Jim

Title: Compression Check Range?
Post by: Jeffy on December 20, 2006, 12:04:52 PM

Well, that's pretty good compression.  Although I'd like to see each cylinder listed instead of a range.  If one's 140 and all the others are 150, I'd be wondering why it's lower.  Although it's got good compression.  Jeep recommends 120-150 as good.  Max variation is 30psi.

I'm not sure what's the deal with the oil pressure.  If they're doing a cylinder leak test they should be using around 80psi to replicate the engine's normal pressure.  For a compression test, I've never pumped up the oil pressure.  Although I was doing compression tests around 15 years ago.

Title: Compression Check Range?
Post by: GlacierJim on December 20, 2006, 09:48:59 PM

Jeffy,
  Once again you have the answers :)

Thanks and wish you happy holidays!!


Jim

Title: Compression Check Range?
Post by: Tall Boy on December 21, 2006, 11:08:19 PM

It'll only take you a little while to check it yourself though.