Valve compression?
 

Hi everyone, I am looking for advice on how to go about fixing my r4unner 3.0l v6 engine. I have done a compression test and the results were
1 - 150
3 - 150
5 - 151

2 - 138
4 - 50
6 - 135
I have added oil to the #4 cylinder and there was no change so I am wondering about what to check for on the valves for that cylinder and how to go about fixing it. Thanks everyone!

it could be a valve...it could be a compresion ring... it could be a blown head gasket. how many miles u got on it?

I got these heads from another guy and he told me there was about 120,000 miles on it. The gaskets are all new.

check the shims.. im willing to bet that one is not lwtting the valve close all the way

I would tear down that side and do a leak test on that head. The quick and easy leak test is to put talcum powder on the combustion chamber side and then pour a liquid (I use rubbing alcohol or mineral spirits) and see if any leaks onto the talcum powder. If it does then the valve is not sealing for some reason. Valve could be burnt, bent, shimmed wrong, etc but at least you have a good handle on the problem.

If all the valves hold fine, then the likely culprit is the headgasket, warped head or block or maybe a crack in the block.

Thanks guys I will give those a try and get back to ya!!!

Hi Guys, I did my valve clearances and these are the results:
#2
exhaust- 0.281 mm
intake - 0.266 mm
#4
intake 0.282 mm
exhast - I couldn't get my smallest guage(0.037mm) in there. It was very very tight.
#6
exhaust - 0.230 mm
intake - 0.281 mm

So I was just wondering what my next step would be because it was my #4 cylinder that was getting th 50psi on the compression check. Any help would be much appreciated. Thansks.