compression at 120

[josephg15]

all cylinders have a 120 compression...is this good or bad...thanks sr20det redtop

[Luke]

Tell us what procedure you used to check compression. That does not sound right and it would be nice to tell you did it wrong rather than you're engine needs rebuilding. If you're sure you did the test right, try putting a cap-full of engine oil into the cylinder and try again. If that brings the compression up, your rings are worn to hell. I can't say it's that because you're reading 120 across the board.

[AmoebAssassin]

Were you at full throttle while cranking the motor? If not your comp tests will come out low!

[Luke]

Were you at full throttle while cranking the motor? If not your comp tests will come out low!

Exactly. Warm the engine up, disconnect the CAS, pull the fuel pump fuse, remove all spark plugs and crank the engine 4-5 times holding the throttle wide open. Report back to us with the results.

[spider_slayer]

i've done a compression test on a cold engine before by accident. and i got 120psi all around. try again. but the good news is that the cylinders are all at the same compression.

[josephg15]

ill have to wait till tuesday to do another compression test because my gauge is at work...ill get back with the results then...thanks

[S13240]

Make sure you warm up the engine first then do your compression test. Anything below 126 or was it 128 psi is bad(minimum values per fsm). Pretty much the engine is a goner(needs rebuild).

Max is 156 psi or 160 psi...can't seem to remember...accidentally formatted my hard drive the other night and still haven't downloaded a fsm yet.

Anything numbers higher than that, you probably did it wrong or have a magical engine.