Hey, i have a little problem with an ls motor my friend just put back together. Actually its a big problem but ne way. so my friend calls me today and hes saying his motor isnt running after he just replaced piston rings in his block. he put the motor together and when he cranks it it doesnt turn on. so i go there and make sure hes getting fuel and spark. all seems well. then i do a compression test and the first two cylinders are showing nothing. The third one has perfect compression and then again the last one shows about 3 psi. Were are about to take the head off again and see whats the problem. But before we do that do u guys have any ideas on what it can be? I was thinking he could have put the headgasket on wrong. the head or the block could be warped so were gonna check all that thursday. Has this ever happened to any of you?

 

need some answers

 

could be bent valves if the engine was put back together with the cam timing all out of whack. You'll need to do a leak down test if you don't want to take the head off right away but one way or another it's going to come back off.

 

the timing is perfect. the motor ran before it was taken apart tho. i just hope its not a warped block or head. that would suck.

 

check valve adj...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GsrIntegra789 &raquo;</TD></TR><TR><TD CLASS="quote"> i just hope its not a warped block or head. that would suck. </TD></TR></TABLE>

If it was, it would have shown up as a problem before you tore it down and would have found evidence of the problem then. If the head didn't seat properly on the dowel pins, possibly...just do a leak down or remove the head and see what's happening.

 

good point. thanks guys ill keep you updated. i wont get to work on it till thursday, oh well.

 

today i took the head off. and cylinder 1 has a big gash down the middle of it. that would explain why im getting no compression out of that cylinder. but how come number 2 and 4 didnt get any compression either? headgasket was on right and the timing was dead on. idk what the problem is. i checked the head and the valves are not bent.
Any ideas/?

 

So you're saying there is a gash up and down the side of the cylinder bore? If everything else looks ok and valves aren't bent or leaking (would have been a good idea to do a leak down test before you removed the head) I would say possible incorrect piston ring installation.

 

90% of the engines people build and never start is incorrect valv adj... yes IT WILL NOT START

 

Guy above is correct. Had it happen to me on several occasions. I was like how the hell can i have zero compression?? Then the valve adjustments and bam! Worked like a charm. See, i made the mistake of taking the head off, wasted a good headgasket while at it. I see that you already took yours off too.. Good luck

 

Car is running. I took the piston out. honed the cylinder as much as possible without making it too big for the piston. (there is still a gash there). Put the piston back with new rings. put the head on did a full valve adjustment. and the thing started right up.

 

no i dont know what im talking about...

 

on the LS cylinder head if you mix up the lifters (which is extremley easy to do) you will get no compression.

valve adjustment

 

I think his pushrods were too long. Saw that on OCC.