Compression test not so good

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Dec 27, 2014 | 11:44 AM

scatgo

Thread Starter

Junior Member

Joined: Jul 2013

Posts: 44

Likes: 1

Model: Cherokee

Compression test not so good

From back to front I got 170 170 155 120 90 140. This was done with the engine cold and the gas pedal to the floor.

Last edited by scatgo; Dec 27, 2014 at 12:15 PM.

Dec 27, 2014 | 12:05 PM

CCKen

CF Veteran

Joined: Aug 2010

Posts: 8,357

Likes: 102

From: Canton, MI

Year: 1999

Model: Cherokee

Engine: 4.0

Quote:

Originally Posted by scatgo

From back to front I got 170 170 155 90 140. This was done with the engine cold and the gas pedal to the floor.

There's one missing (tee hee).

Add a teaspoon of motor oil in the cylinder with 90 psi and try it again. If it comes up the rings are bad.

If it doesn't come up by adding a bit of oil, there may be an issue with a cracked valve, a chunk of crap stuck in the valve seat, or part of the piston ring lands blown out.