Hi All,

I am new to the Jeep world. I just purchased a 2000 with 125k miles on it. It is idling REALLY rough so I decided to change the plugs. All the plugs looked good except number 2. It had oil all over it. I put a new one in and alas oil on it again. I did a compression test on the engine here is what I found:

Dry
1. 120
2. 90
3. 125
4. 115
5. 110
6. 118

Wet
#2. 95psi

I only did the bad one with wet test as all other seemed close to acceptable tolerances.

There is a black spot on my air filter as well. Could the CCV be clogged causing things to get past the valve seal?

Jeep manual say 30 psi is within the acceptable range for the compression test. I do not have the history on the vehicle. There were no stored codes when I plug in the OBD sensor, but the check engine light does come on after a little bit of driving. Do you think this is piston rings or the valve seals (praying it is the valve seals)? I have attached a photo. Any help would be appreciated. Thanks!

 

That engine must have had a rough life to loose that much compression with "only" 125K miles. Given your compression wet/dry test results, it appears that the cylinder is loosing compression due to bad rings. You should have seen higher wet compression numbers if the top end was at fault. Sorry, looks like your engine needs a complete rebuild or be replaced. And if it were mine, I would think twice before slapping that "0331" head back on while doing that.