djteggy99

ok so we just got done rebuilding my gsr motor replacing the old pistons and rings with brand new itr pistons and rings last Saturday and probably not even 100 miles on the motor yet. Will me and my bro did a compression test on it today and it came out with a really uneven number. when tested the numbers came out 200,140,150,190 is it way off or is it just because the rings are seated yet or are the numbers too off. I mean i havent even putted at least 100-200 miles on the motor yet.

mar778c

iTrader: (1)

Did you disconnect the injectors?

djteggy99

no..i remembering read on ht that someone had uneven numbers like mines but he said that later on his numbers wasnt uneven no more cant remember my bro says that i have bad exhaust vavles which we did replace two exhaust valves in number one which the number was 200 but im thinking its just gonna take time to seat my rings then itll get even later on. If the reason are my valves imma have to rebuild the head too which i dont really want too unless i know it is because of the valves. will the bad valves cos my compression to be uneven too?

mar778c

iTrader: (1)

If you did not disconnect the injectors then you did not perform the test correctly.

Yes, leaky valves can yield bad test results. Perform the test correctly and report the results.

djteggy99

ok thanks

djteggy99

ok today me and my bro did a test again it read #1 220 #2 140 #3 120 #4 200. 1 and 4 looks good but 2 and 3 are way off probably my valves for sure now unless anyone else can have a idea what is wrong.

00Red_SiR

Have someone perform a leak down test and listen in the exhaust and intake for air escaping. When you installed the new pistons and rings did you re-bore the block or at the very least have it rehoned?

Scott_Tucker

You do not need to disconnect the injectors before doing a compression test. You should disconnect the connectors to the distributor or pull the ignition fuse (if it has one) so you don't accidentally light yourself on fire.

Did you do a wet compression test too? That would tell you if your rings are sealing. I doubt the numbers are low because your 'rings haven't seated yet'. If a wet test is inconclusive, you need to do a leakdown test on those center two cylinders to determine where the compression is leaking.

djteggy99

its probably bad valves the No.1 which had 220 was the one exhaust valve that cracked and we replaced it with brand new oem ones and compression looks really good.We looked at the other valves too they looked bad too but we thought we would be ok but now i see i will have to replace all 8 exhaust valves.

Scott_Tucker

You may be right but why not just do a leakdown test now and confirm it? Instead of removing the head, spending money to put valves in it, reinstalling it only to find out your rings aren't sealing? Basically do the test now so you can take care of everything at once. By just going ahead and replacing the valves you are just guessing and guessing doesn't fix cars.