Compression numbers...

[918_gsx]

Ok. Car has been running crappy and starts to overheat when you get on it. Can pudder around town though and not overheat. Also, it tends to be hard to start all the time. Just did a compression test on all 4 cylinders. Here's the numbers...And please, try not to laugh too hard while reading these numbers
Cylinder #1...14psi
Cylinder #2...17psi
Cylinder #3...17psi
Cylinder #4...45psi
Anyone ever see numbers this low and the car still run? Granted, you can not take your foot off the gas the whole time, but it still runs. I'm kinda lost. And very little smoke and only at initial start up. Oil is not milky...
Any advice?

 

[19Eclipse90]

Do a leak down test to figure out where your compression is leaking out. Just to be sure, you ran the compression test with the engine warm and the throttle wide open, correct?

http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

 

[918_gsx]

No, i didn't do it with WOT. Didn't realize i really needed to. But I will right now and be right back. Also, any good threads on doing the leak down test on this 1g anywhere? Thanks.

 

[19Eclipse90]

No, i didn't do it with WOT. Didn't realize i really needed to. But I will right now and be right back. Also, any good threads on doing the leak down test on this 1g anywhere? Thanks.

...http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html...

I think there's one somewhere...

 

[918_gsx]

Ok, I just did the test at WOT. Just showed a 3psi increased, so not much difference. Sound like a head gasket?

 

[95dsmgsx95]

Maybe a headgasket but try to put a cap full of oil in one of your cylinders and redo the test in that cylinder.

 

[19Eclipse90]

Likely. http://www.dsmtuners.com/forums/articles-engine-fuel/336535-do-you-have-blown-head-gasket.html

A leak-down test will tell you for sure.

 

[kchaazz]

Get a quart of oil. Dump half a capfull or so into each cylinder and retest. If the numbers go up significantly, your rings are shot. If the numbers dont go up much, then youre lucky and its the headgasket/ valves/ seats.

 

[918_gsx]

Ok, thanks guys. I'll try with the oil in just a bit and let yall know something.

When doing the compression test on this motor, are all plugs supposed to be out at the time or just for the cylinder you're checking?

 

[19Eclipse90]

All four should be removed.

 

[918_gsx]

Ok thanks man. I think I had a bad cap. I replaced it and been driving around hard trying to get it to overheat, but nothing. But I did notice that my upper radiator hose feels like there's so much pressure in it that it may blow. Even well after driving and the car is cooled. This normal on this motor?

 

[19Eclipse90]

What did you decide was the cause of the low compression?

 

[918_gsx]

I think it was just a bad cap. Can't test compression today so I'll know soon enough I'm sure.

 

[19Eclipse90]

Bad cap won't cause low compression.

 

[Tyeler18]

A bad cap won't cause low compression.

Edit: Too slow for me. Just because it isn't overheating anymore, doesn't mean everything is fixed. You need to figure out why compression is low.

 

[918_gsx]

Well, that's the only thing I changed and somehow the car is starting easier, idling better, and has gained some power back. I'm lost.

 

[miguelmcv]

If your Idle got OK, then that's sweet for you so you can drive the Car.

(BBBBBBUUUUUUUUUTTTTTTT).

Seems that you have some Major Problem in your Cylinders, which is a major problem then Idling...

Do a leak down compression test, To check where is your Pressure going to.

Other wise you will end up with a broken engine at any time.

 

[918_gsx]

@Miguel...That's what I'm doing tomorrow. I've never done a leak down test before so I hope I get it right

 

[19Eclipse90]

Compression is dependent on things in and immediately around the combustion chamber. Not trying to talk down to you here, but that is valves, head gasket, pistons, rings, head, and block. Something related to one of those components is the cause for low compression. Do the compression test again with the engine at full operating temperature, with all spark plugs removed, with the throttle wide open, and the MPI fuse removed.

 

[rlacasse1]

Are you saying a bad cap like in the ecu or what? How the hell would that cause low compression?

Listen to 19Eclipse90.

 

[miguelmcv]

He said it got fixed, But I guess he was talking about the Idling, (Not about the Compression).

 

[Calan]

I honestly don't see how the car would be running at all if the compression is truly that low across the board. Numbers less than 20psi per cylinder point at MAJOR problems with the engine. If it does run with that little compression, it would be so rough and powerless that it would be obvious that something is seriously wrong.

My money is on inaccurate test results. Beg, borrow, or steal another comp tester and test it again, making sure to follow the correct procedure. Then do a leak-down test to verify the results.

 

[918_gsx]

@rlacasse1...if you would have read the whole thread, you'd know what the hell I'm talking about. Anyways, I'm wondering myself if it was a bad compression tester. There's no way it should be driving right now without any major problems. I can even get 14psi out of the car right now and no problems.

 

[rlacasse1]

Uh, I did read the entire thread. And unless I'm blind, the first thing you said about a cap was "I think I had a bad cap. I replaced it and been driving around hard trying to get it to overheat, but nothing." Which I guess you may be talking about your radiator cap. Fu(k, I don't know, you never said what cap it was. Maybe it was your oil cap, or maybe your coolant overflow cap. See where I'm going with this?

Regardless, none of them would affect your compression. So either you did a compression test wrong. Or you need a new gauge.

But thanks for being a dick anyways.

 

[918_gsx]

Ok, sorry for not being so literal I guess. Anyways, the radiator cap.