Originally Posted by critter sit-t
hey I ran a compression test on the car today cylinders 1,2, & 4 were at 90 at idle and 150 at high rpm. now # 3 cylinder held absoutly no compression. now just to make shure im right #1 if the head gasket was leaking i would have lower compression in 2 & 4 correct?? ok now theroy #2 lets say that the person who put the pistons in didnt put the rings on correctly and aligned the gaps up instead of staggering them. if the rings were aligned than the cylinder would hold no compression am i correct on that?? and option #3 the valves in # 3 are jacked. I just would like some advice before i tear off the head and oil pan tto rip out the pistons to fix the rings. if its the valves im going to just pull the motor and replace it with a stroked B16 that i have. thank you for your inputs in advance.I finaly got the problems fixed that the shop messed up but the motor is still holding back after 4,000 rpm so I did a compression test and this is what i found. also does anyone know the equasion to figure out what compression pistons I have?? there supposed to be 8.5:1 but i want to be shure thats what theyre at so i dont grenade the motor when i put on he turbo. ok thanks again all.
Critter >:^)
2 adjacent cylinders showing bad compression numbers signifies a bad headgasket. 2 & 4 aren't even next to each other, so they have no effect on this; only adjacent cylinders. If the rings are aligned, it would still hold compression because only the first ring contributes to compression. The rest scrape the oil off the cylinder wall to prevent it from being burned. It would hold some compression this way but I would think that it would burn tons of oil. The reasons why it had no compression is either A) broken ring lands/cracked piston/cracked cylinder walls or B) you have stuck valves. Bad or aligned rings will still hold compression, so I think it may have to do with the valves or ring lands. For compression calculator, go to
www.c-speedracing.com.