Boost leak test help?

[matt98eclipse]

Today I did a boost leak test I made one just like this one in this link
http://www.dsmtuners.com/forums/showthread.php?t=201554

I found a couple little leaks I had in my intercooler piping and fixed them! Im pretty worried cus i found a little leak comeing from my valve cover breather! What could be causing this???

Please help guys, thanxs

 

[Spln_Hrd]

You have intake valve is open on a cylinder with a slight leak into the crack case through the piston rings(kinda normal) more than likely. It could also be leakin through a valve guide seal, but I doubt that because it would burn oil pretty good if you had one leakin that bad.

 

[romeen]

More than likely a leaking PCV valve. Remove PCV from crankcase and repeat boost leak test to see if this still happens. You can also get air past the turbo seals which then gets into oil line and into crankcase. This doesn't necessarily mean the seals are bad though, the oil pressure seals them when motor is running.

 

[kenamond]

Make sure you do the test on a warm motor so that the rings are sealed better. In addition to intake valve seals and ring blowby, it could also be your PCV valve (back-left side of valve cover looking into the engine bay) and/or turbo compressor seal (not necessarily a bad thing) letting boost test air blow through the oil return tube to the crankcase. Both will end up leaking out the VC breather. If you can't hold 20psi without it leaking down more than 1 psi every few seconds second or so, give or take, track down the leaks. With good compression and no boost leaks, you can hold 20psi for many seconds without it dropping. I'm not sure if you have to have it that leak-proof, though, but it certainly wouldn't hurt.

Check your PCV, BISS, TB gaskets, TB shaft seals, injector insulators, BOV flange, couplers, IM gasket, and IC (can have corrosion holes or punctures) with a soapy water spray bottle.

Block off the BCS or MBC line coming off the compressor, too, as this leaks a bit of boost as well (both ball-spring and bleeder boost controllers have a bleeder hole).

EDIT: romeen types faster (and less) than I do.

 

[matt98eclipse]

k thanxs im gonna buy a new pcv valve!

The car doesnt smoke at all and hardly burns any oil at all

When i did the test the car wasnt warm so im gonna get the car to full operating temp and retry it again but when I tested it i put 4 pounds of air and that air would leak out within a couple seconds

 

[kenamond]

k thanxs im gonna buy a new pcv valve!

The car doesnt smoke at all and hardly burns any oil at all

When i did the test the car wasnt warm so im gonna get the car to full operating temp and retry it again but when I tested it i put 4 pounds of air and that air would leak out within a couple seconds

Whatever you do, DON'T get anything other than an OEM PCV valve from your local mitsu dealership (mine was like $4 I think). Autozone, Carquest, etc. valves leak out of the box, because they're not designed for turbocharged applications. Also, don't be completely suprised if the OEM valve leaks a bit, too.

May want to do the boost leak test again on the warm motor before you start blaming the PCV. A cold motor can leak A LOT from blowby. It was a night and day difference on my car, and I have great compression.

 

[matt98eclipse]

I just rebuilt the motor like 4 weeks ago the motor has a little over 500 miles on it. I did a compression test on it around 200 miles and it was 200,180,180,180

 

[romeen]

But I'm sure you did the compression test on a warm motor. Mack is right, you would be surprised how poorly the rings seal when cold.

Here is a check valve that some of us on the forums have started using between PCV valve and IM to combat the all too common leaking PCV's. They are cheap and work quite well.
http://www.usplastic.com/catalog/va...ory_name=45&product_id=15641&variant_id=64175

 

[matt98eclipse]

Yes, when I did the compression test with motor at full warm temp and at WOT.
Ill check those pcv valve out.

thanxs

 

[kenamond]

No. What I mean is that your boost leak test will leak worse on a cold motor than a warm motor. The rings haven't expanded, and the increased blowby will leak out the VC breather. With my motor cold, I leaked down from 20psi to 15psi in about 3 seconds. With a warm motor, I leaked down from 20psi at about 1psi every couple seconds. Big difference! Warm up the motor, then do the boost leak test.

 

[matt98eclipse]

Sorry for the misunderstanding I going to try it again today with a warm motor and see what happens.