Hello everyone, So I got a compression check done on my 92 3.0 truck and cyl #3 has low compression at 65 all the others have 125-135. I think i might have a stuck valve or something. If you guys could give me some ideas and things to do places to look kind of stuff would be appreciated...... Thank you all

Oh yea im going to work now when I get home tonight I will log back on....

 

check valve clearances?

 

Ok I'll search how to do that also what I'll need. I done valve adjustments on 22r motors but never 3.0 I have never even taken off the valve covers yet its all new to me. If anyone gots any info on how to do this feel free to share.... Thank You

 

what does it cost to get a compression test done?

 

If you paid to get the compression test done, you should've also had them do a leakdown test to isolate the source of the problem: intake valve, exhaust valve, head gasket or piston.

 

The other cylinders are also very low. 180 psi is what a healthy engine would give, so it sounds like you need to do the leakdown test to determine if you can just rebuild the heads or if a total rebuild is in order. It's not uncommon for the 3.0 exhaust valves to burn and lose compression, but for the bottom end to be still in good condition.

 

My compression test cost nothing I did it myself. Also if I had a compressor I could preform leak downtest, I need to get one. I believe 175-180 should be on a fresh motor not one with 150k +. I know its probably be best to rebuild the head but no cash for that, so I'll keep searching.

 

Well, the poor-man's leakdown test is to do a compression test on the bad cylinder, then put some oil in and do it again, compare the results.

If the readings are the same, it's gonna be the valves or gasket; if the second reading improves, it's the rings.

Don't expect too much from this, I'd say.

Bugs is right, though. They should really be above 150. Try that same test on one of the better cylinders just for comparison.

By the way, when you did the check, you cranked it over several times for each cylinder, right? And the same number of cranks for each?