need alittle advice

[preston240sx]

ok so i just bought a new used head for my rb20 over the past few weeks waiting for parts i slowly put my rb20 back together so last night i put the timing belt on an decided to compression test everything .......... while i was there everything was great except ....... number 3 was dead nothing would register on the compression gauge ...now my question is .... sound like piston rings or a bent valve on the number 3 side ? lemme know if i have to i'll tear it all down again....

[240z4u]

You can't tell without doing a leakdown test. Hook an air compressor to the compression gauge thing and see where the air is blowing out.

[SullivanRacing06]

pull the head, remove the cams, pour gas or mineral oil in the combustion chamber of the cyl you think is low, see if ne fluid leaks thru, if so them your got a cracked head or a bent valve

[preston240sx]

ok just hook up the compressor........ number 3 never fully closes.... was told lifter could have a shim out / need to checked with gauge or ... bent valve..... so this weekend i get to do headwork yeyyeyeyeye .... i had to learn the hard way to not cut corners now it biting me in the a**

[Yellow4g63]

ok so i just bought a new used head for my rb20 over the past few weeks waiting for parts i slowly put my rb20 back together so last night i put the timing belt on an decided to compression test everything .......... while i was there everything was great except ....... number 3 was dead nothing would register on the compression gauge ...now my question is .... sound like piston rings or a bent valve on the number 3 side ? lemme know if i have to i'll tear it all down again....

You didn't get the head checked out at a machine shop before you put it on the car?

[preston240sx]

aight finally a weekend to work on the 240 ..... so the problem ended up being 2 bent intake valves ... but the problem seem to be more then that .. has all my friend and me shaking out heads ..... after replacing the two bent valves we reassembled everything back put the timing back in... then did another compression test and got zero compression again.....so... back to the drawing board we hooked up the head again did a leak down test and everything held.... no leaks no piston blow by... and thats where im stuck at has anyone heard anything like this???

[Carl H]

cam timing off by chance?got the engine 180* off?

[preston240sx]

ima double check everything but im pretty sure its in time... on the compression side but i'll check it again but im sure its good to go i'll keep everyone updated ... i've been searching cant seem to find this problem with anyone else

[preston240sx]

alright guys just got my car running... im very happy with the outcome .... bought a disassembled block found 2 bent valves replaced the valves bought a gasket kit and i'm pushing 145 psi across all 6 cylinders.........its also running super smooth could'nt be happier for the 300 bucks i spent on block and gaskets ..also after i hooked everything up i got compression on the number 3 cylinder like i said 145 across the boards .. on a super cold engine
Modified by preston240sx at 10:10 PM 12/10/2009