Opinions on compression test results

[rocafellafw]

Just trying to get a idea of what everyone thinks my problem could be. Ran a compression test and my numbers were

100-105-106-96

Next up is to do it again and add oil to check and see if the rings are bad. After that a leakdown test. Basically I just want opinions on what those low numbers across the board could mean. Also when I do a leakdown test what would help me tell if it's valves instead of rings or vice versa ??

Some more useful info:
Headgasket/valves/tbelt were all replaced 10k miles ago
Bottom end mileage is unknown
Car does not smoke
Runs/idles fine
Afr's are great for idle, cruise & wot, never ran more then 12psi

Here are the results I got after testing again:
Cylinder 1:
Dry = 105
Wet = 140

Cylinder 2:
Dry = 95
Wet = 120

Cylinder 3:
Dry = 100
Wet = 119

Cylinder 4:
Dry = 95
Wet = 125

 

[92AWDHX40]

The first two look low do another test to make sure.

 

[rocafellafw]

The first two look low do another test to make sure.

Just the first two ?? We did all cylinders about 3 times and the numbers for all four cylinders were +/- 2psi of the posted results. Any opinion on what you'd say is the issue ?

 

[PieEyedPiper]

The first two look low do another test to make sure.

Only the first two?

OP, continue to do your tests. Could be a bad compression tester, even.

 

[rocafellafw]

Only the first two?

OP, continue to do your tests. Could be a bad compression tester, even.

Ok will do. Problem is the car does run pretty badly, bucks very bad in low rpm if I don't give it a good amount of throttle, it pulls strong up top but just lacks any power down low. Also the turbo (16g) takes till about 4500 to spool up

 

[92AWDHX40]

Oh yeah, some reason i didnt see it that well.

 

[rocafellafw]

Should the car need to be at TDC or anything for compression test or just a leakdown ?

 

[19BLACKGST98]

Have you done a boost leak test lately? (for the slow spool)

When my motor was built it read 140's across the board and I was told that it was lower than I expected due to my cams?

 

[DSMTyson]

Do a wet compression test and get back to us on the results.

 

[canada4g63]

I wouldn't drive it anymore before you cause more damage.

 

[herms99gst]

Are you doing the compression test at wide open throttle?

 

[xrdgx]

Try new compression gauge

 

[Magrud3r]

Do a wet compression test and get back to us on the results.

This. I'd also find out if the tester was accurate. Sounds like the car does have issue(s) though from what you said, try again and come back with the results

 

[97ebaygst]

is the car fully warmed up?

 

[99gst214]

I would try the wet compression test like stated before. Also borrow another friends tester just to verify accuracy. If you add oil and the numbers change, then its most likely rings. If they don't change then its something up top. I personally am thinking its something up top, just because that was the last thing messed with. Car needs to be tdc on leak down test, which would be your next step, before taking the head off. Also you could do a boost leak test, just for the hell of it, but a poor valve seat will cause the low compression and hurt spool time.

 

[rocafellafw]

Ok thanks for all the info/replies guys. The car was fully warmed up. A boost leak test has not been done lately but I will be doing that and a leakdown the same day once we get the compressor out. I will also have a friend lend me his compression tester to make sure mine is accurate. Also the test was not done at WOT I didn't know about trying it like that.

 

[DSMTyson]

With the numbers that you posted. Doing the compression test at WOT won't give you much different results.

Do a wet compression test.

 

[eli96talon]

Those numbers are rather low...ide imagine the car would smoke,o have no power...good compression pistons is what moves air into the turbo and helps it spool when it should.do a wet test and see what happens.

 

[reddragon1]

Try a different tester.

 

[rocafellafw]

Try a different tester.

Ok just got doing another test wet & dry with the car a little warmer then last time. Also did with and without wot and got no different results.

Cylinder 1:
Dry = 105
Wet = 140

Cylinder 2:
Dry = 95
Wet = 120

Cylinder 3:
Dry = 100
Wet = 119

Cylinder 4:
Dry = 95
Wet = 125

So I'm assuming the rings are bad but one things worries me. During testing air was escaping from other cylinders that were not being test. So does anyone how any opinions ? I have already priced up a npr rebuild kit that is in my price range.

 

[DSMTyson]

Bad rings, possibly a couple slightly bent valves.

 

[rocafellafw]

Bad rings, possibly a couple slightly bent valves.

Well I'm glad I been getting the prices together for everything over the last couple days. Thanks man, would you recommend a leak-down test or do I pretty much got a idea of what the problem is ? I plan on swapping to good condition stock head for awhile so if there is a valve problem it would not matter anyway.

 

[DSMTyson]

Well, you've pretty much got all of the information you need now. And yeah, it won't matter anyways if you are swapping to a known good head.

If they aren't bent, they might just not be seating for whatever reason. Might just need a valve job.

 

[rocafellafw]

Sounds good. My plans are 300-350hp so during the time I have the stock head on the one I have now will be stripped and rebuilt with better cams, springs, & valves. Thanks to everyone for the help.