First compression test not so good

[davidalindsey]

Okay so I finally got around to doing a compression test.
I followed a great how to on jsamotors.com
My numbers dont look so good.
Starting left to right Cly 1, 2, 3, 4.
Dry test: 125, 110, 110, 111
Wet test: 129, 119, 119, 131
These numbers are all well below the service limit
Please tell me how to get my compression back in order

I also did a boost leak test up to 17 psi
VIDEO LINK 1, A video of the boost leak test.
VIDEO LINK 2, A video of the vent breather under a boost leak test.
And the main video here:
YouTube - Boost leak noise in crank cover, losing compression through the rings?
Tell me what you think
Thanks for yhalls input/help.

 

[JoshCorlin]

Did you do your compression test with the engine at full operating temp. Do a lap around your town and try it again. As far as the leak, If it were your rings, you would hear a leak from the dip stick, it could be you valves or your head. You should also run a vaccum test and that will give you some more insight to your problem if it were the head or its components.

 

[Fast-Orange]

you need to roll your crank over so your valves arent open, i put a regulator on my testor so i can keep constant pressure and roll the crank over to seal it

 

[davidalindsey]

Yes the car was warm. I drive it home from work then waited a couple of minuites to do the compression test.
I dont hear a leak from the dip stick, just thru the oil cap hole.
How do you do a vaccum test?

 

[ramsack]

the breather could just be your pcv valve leaking. cap off where it goes on the manifold and make sure whatever you use is on there good, and test again. if there is no breather leak then you probably just need a new pcv valve, and they are cheap from the dealer.

 

[davidalindsey]

you need to roll your crank over so your valves arent open, i put a regulator on my testor so i can keep constant pressure and roll the crank over to seal it

So you mean I need to Bring the cylinder's TDC (top dead center) so that all the valves are closed?

the breather could just be your pcv valve leaking. cap off where it goes on the manifold and make sure whatever you use is on there good, and test again. if there is no breather leak then you probably just need a new pcv valve, and they are cheap from the dealer.

I did the test just after I put in a new OEM PCV and a USP Check valve.

 

[ramsack]

well very good, then it is most likely just worn out rings since your compression went up on a wet test. i'd say cylinder 4 is the culprit since it went up 20 psi. you could also do leakdown tests as well, and i think cylinder 4 will show how bad it is then. i would tear down your engine to a short block and take it to a machine shop and have them check it out. you may be able to get away with just rings work, or you might have to go oversized. they will be able to tell by measuring clearances and whatnot.

 

[davidalindsey]

^^^^ okay then, how much and where do I get piston rings from?

 

[ramsack]

there are various vendors that belong to the board that carry stuff like that.

 

[davidalindsey]

Ouch $158.50 for a set of oem rings..
Is it okay to dirve the car with numbers that low?
The car runs great, boost full at 16psi, no loss of power or anything like that.
I was thinking later on down the road I wanted to get forged internals.
Like Wiseco Pistons and Eagle Rods. Would the engine be okay for a while till I get the funds for built internals?

 

[Fast-Orange]

yes you need to roll it over to tdc.
a new pcv probably wont seal great until you drive around for a bit mine didnt so just block off the hose, you can block off your uicp and just test the rest of the system and test the engine seperate.
If your complaining about 100 and some for new rings...why did you buy a dsm? there is a while lot more to an engine rebuild then just new rings...do some research and get an understanding on what will need to take place when you tear it down.
Yes you can drive it, it already needs a rebuild anyways so who cares unless your worried about your turbo. its not going to blow up in the next week. you will most likely start burining oil and have a lack of power, make sure you check your oil once in a while for fuel.

Good luck

 

[davidalindsey]

yes you need to roll it over to tdc.
a new pcv probably wont seal great until you drive around for a bit mine didnt so just block off the hose, you can block off your uicp and just test the rest of the system and test the engine seperate.
If your complaining about 100 and some for new rings...why did you buy a dsm? there is a while lot more to an engine rebuild then just new rings...do some research and get an understanding on what will need to take place when you tear it down.
Yes you can drive it, it already needs a rebuild anyways so who cares unless your worried about your turbo. its not going to blow up in the next week. you will most likely start burining oil and have a lack of power, make sure you check your oil once in a while for fuel.

Good luck

Okay thanks for the tip.
Oh and I wasnt complaining about about the money for new rings.
I just did not realize that rings costed that much.
I bought this dsm cause it is to replace my 03 srt-4, I already have a 99 gs oz edition. Ever since I had the gs I have wanted the turbo model and i found a great deal on a 98 gst. So I sold my srt-4 and bought the gst. (I just didnt like the neon).

So I will be getting some Wiseco or je Forged Pistons & Manley H-Beam Rods.
Just waiting for my tax refund to get here.

 

[Zincone91]

Well i just did the head gasket to my car cause i overheated it on highway and i was wondering why my compressions are around 80-120 and they only go up 10 when wet... my questions are what could be some of the causes of this???

 

[okm12346]

It may sound stupid, but did you have the TB wide open. Closed TB will trow off the numbers big time.

 

[Zincone91]

What is a TB..sorry I'm new to this stuff

What would i do to close the TB

 

[McD]

He is talking about the throttle body (TB) just put a brick on the gas to keep it open