Bad compression

[Wing0tj]

I have been having problems with vacuum for awhile and I just recently had a compression test done, and the readings came back as 145,135,105,135, dry, and 160, 155, 120, 150 wet...I know that when you put hte oil in it should raise compression ~30psi or w/e we are measuring in... I was just wondering if anyone had see numbers like these before, where on of the cylinders is significantly lower than the others, or if andyone has any ideas on causes. that would be great. RIght now I really think it is rings tho... any idea appreciated

 

[luv2rallye]

I just recently had a compression test done, and the readings came back as 145,135,105,135, dry, and 160, 155, 120, 150 wet...I know that when you put hte oil in it should raise compression ~30psi or w/e we are measuring in...

If the compression raises significantly when you add oil THEN it means your rings are worn/leaking. Adding oil should NOT raise compression much on a good engine. Also it is VERY important to have all cylinders read within 10% of each other. Your 105 cylinder indicates a problem like a leaking/stuck valve. Do a leak down test to tell.

 

[Wing0tj]

what about the valve being bent...is it possible for the valve(s) on one cylider to get bent? or would it be something like the lifters on that cylinder...any idea what might cause it... cuz I have no way to have a leakdown test done anytime soon.

 

[Defiant]

#3's got a weak valve. Most likely from face/seat wear. The next step will be head removal. How many miles on that bottom-end?

 

[Wing0tj]

I dont know how that could be it is brand new head...

bottem end has 122K on it tho

 

[royale10]

the idle vacuum is also pretty low. it is usually around 15 in mg or less. it is rough but not usually rough enough to make it stall. im also thinking that we need to put some new rings on because the head is brand new. unless we screwed something up putting it on which is very unlikely.