miskatcitnamor

So I finally compression tested my car. Should have been done ages ago but there it is.

Results were 160, 155, 153, 160

All results are close together so that check passes but obviously the numbers are dismally low. Did the test with a Harbor Freight US General quick disconnect kit. Not sure if the equipment or myself could skew the numbers but frankly, I feel like that is grasping at straws.

So I have an engine that tested poorly.

The question is... now what?

baZurk

Was the engine warm when you tested it? Did you push the throttle open when you cranked the motor over? Next step would be a leakdown test to see how much pressure you are really losing.

MR.T

I would bet you're fine. I have a HF oil pressure tester and it's gauge is way out of whack, so there's a good chance it may be the gauge. Like as said before there are certain things like warm motor, pulling fuel pump fuse,etc... That'll result in higher numbers. You're definitely consistent, so that's a really good sign.

yamahaSHO

As stated, was your engine warm and what is your altitude?

miskatcitnamor

Engine was fully up to temp. Altitude was 430'

I made sure that the throttle was wide open, let it crank for 10s on each cylinder.

yamahaSHO

Was there a reason you tested the compression on this engine? Were you experiencing poor performance? If not, I would try another gauge and see what it says if you're worried about low numbers.

starchland

A cold good motor will still test over 200 from my experience, cranking 7 times. Maybe try another gauge and verify it is screwed in properly

miskatcitnamor

One thing I noticed was that when screwing the hose into the engine it never got tight. Seems that the hose spins on the threaded piece. (Lacking vocabulary, I apologize.)

It looks to be by design, though I'm not certain. I did get it as tight as possible, though.

I decided to test it because it had never been done, to my knowledge.

I guess the next step is a leakdown test before I decide what to do about these numbers.

I'm guessing my options are pretty limited and somewhat ugly.

yamahaSHO

Buy, borrow, or rent a better compression tester if you're worried. Unless you the motor is of high mileage, abuse, or your were missing performance, I wouldn't worry about a leak down tester. To make you feel better about the low numbers, a non HF setup may test more accurately and get rid of the crappy gut feeling your probably have.

MR.T

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