alright, the car overheated once about 6 months back and has been sitting in my garage since then getting ready for the turbo kit. I did a cold compression test on the motor 2 weeks ago. #1 cylinder pulled 110 psi, #2 cylinder 130psi, #3 150psi, #4 175 psi. The motor is a b16 block gsr head, forged rods, 9:1 forged pistons. The motor was freshly rebuilt and has less then 1000 miles on the whole setup. Why would i get results like this, i know doing a compression test cold may give me inaccurate results but damn! Could it be that the rings are not sealing and could be sticking when im turning over the motor. It has been sitting for 4 months at least. I can't turn the car on because the turbo setup is not complete and the car is not tuned. and as it stands, is not together to fireup. any ideas? maybe warped the head? bent a valve, headgasket? i just don't know where to go from here. I dont want to put the turbo kit on a messed up motor. Maybe pull the head? what exactly would i be looking for once i did this.. Thanks for the help guys.

 

Squirt a little oil down the plug holes, turn the motor over a couple times,(by hand, or you'll spray oil everywhere) and try again. If the numbers come up, it's a ring issue. If not, look elsewhere. And don't forget to hold the throttle wide open while cranking for the comp. test.

 

alright ill give that a shot, what im saying is why would i be getting variating psi #'s like that. the engine has sat for a while... could the rings be sticking.?

 

might be the rings, mostlikely the valves arn't sealing coorectly, who knows, engines that have forged pistons are usually bored to a wider tolerance so when they heaat up, everything doesn't mash up... but that still deosn't explain your results

o and by the way, leaving the throttle closed doesn't affect your compression test results.

 

damn this motor has barely been ran. what should i do? tear the head apart and try to find my problem
or finish the turbo kit and see if i get good psi #'s once the engine heats up? im kinda stalemate here

 

any help, please... could i tear the head apart and if I did, can i beable to tell if the head is warped or would the machine shop have to verify that? Give me a ball park price $$ for machine work if the head is warped and if the block needs rehoned, how can i find the problem thats leading to these low compression #'s? Thankyou.

 

do a leak down test. you're doing a comp. test with the motor cold and only turning it over by hand, i wouldn't trust the readings from that. a leak down test is meant to be done with the engine off and is a lot more accurate and will tell you exactly where the problem lies if there is one.

 

well i wasn't turning it by hand. i was turning it over with the ignition but it seemed to crank rather slow like the battery was dead almost. so i turned the crank manually to see if it would turn freely, it does, so i don't think i bent any valves... how do i do a leakdown test? do i have to take the car to a shop?? or can this be done by myself
? how much for a leakdown test? thanks dudes

 

fawk it. im just going to get the car running first, finish the turbo kit, then take it to a shop to be tested. That seems like the most logical solution. No reason making assumptions in the dark

 

i wouldnt bother with a cold compression test. just wait until you can start it and let it warm up a little first. ive tried cold compression tests before and got all sorts of wacked out numbers on very strong motors.. that gave numbers within 5psi of each other when it was warm.