messed up sparkplug,do i need a rebuild??

[juanishio]

i dont want to make this long so here it goes....i was on the freeway ,i was traying to cut down some traffic so i floored it,when suddenly my car started loosing power sounding like a wrx...i got home took out the spark plugs ,turns out that the 4th cylinder had a damaged plug.did a compresion test results were 150 150 150 70...cars still runnin weak is there a way a valve could have hit the sparkplug,or is that something just the piston could have done???my car is an s14 with a s13 sr

[s13silvia123]

pics please..............

detonation?????????

no the valves cannot hit the plugs unless it breaks off and hits the piston as it comes up and hit the plug.

my guess is the piston. you might of melted the piston.

[brndck]

sounds like either melted piston or a valve burned and no longer seating/sealing fully. if you have access to a leak down tester (different than a compression tester) thats your best bet. or you can try adding a small (maybe a tablespoon or less) of engine oil directly in that cylinder (the 70 psi one), and then compression test it again. if your compression comes up with oil in it, you have bad piston rings. its a longshot and you'll need a teardown either way, but... knowing is half the battle right?

[juanishio]

thanks for the help man ill try that out