Boost leak problem! Help! Please!

[chef]

Hi!

I've got a boost leak detector today, connected it onto the turbo and the car could not hold any boost. The car is a stock mitsu eclipse gsx 90mod. The compressor was making 20psi and I heard all the air was leaking under the valve cover.

Took of the valvecover and notice it was a tube that goes to the valvecover where the air was leaking from. The tube I am talking about is the tube going from the intake manifold to the valvecover, not the oilreturn to the intaketube to the turbo.

Why does all the air goes thru this tube? All the air was leaking from that tube into the valvecover and thru all the cracks in the cover. What is this tube for, and can I shut of this tube and then have boost? The manuell boostgauge shows 8-9 psi and my aftermarket boostgauge shows 0,5bar. When I hold a finger on the tube to block this off, The car will hold some boost.

Hope you guyes can help me!

 

[ddavisaf]

Replace the PCV then retest.

 

[chef]

Yeah! Thanks man! That's might be it! Remember I read that the PVC valve should not let air in. But does anyone know why this valve is here?

 

[ddavisaf]

It allows the pressure in your crankcase to escape during vacuum conditions, and it is supposed to seal during boost conditions.

 

[chef]

Shit, will that say that my air may be buliding up inside the crankcase? My compression numbers are: 168 165 140 158

 

[ddavisaf]

Time to tear the head off buddy.
Run a leakdown test to pin point the problem. There should be less than 14 psi between cylinders. Anything more indicates a problem with your headgasket, piston rings, or valve seals.

 

[chef]

yeah.. your right! But I have unplugged the pcv valve now, and something is loose in there. I am sitting with it in my hand and when I blow air thru the valve with my mouth, the air goes thru... so the will buy a new pcv valve before it take the head of..

Thank you for your help!

 

[ddavisaf]

It's supposed to be "loose".
You should be able to blow air through the threaded section of the valve, and you should NOT be able to blow air through the straight fitting section of the valve.

 

[chef]

When I put oil into the cylinder with 140psi, it raised to 148, so it looks too me that the valves on that cylinder isnt good.

So about my problem... It may be the pcv valve and it may be bad piston rings?

 

[ddavisaf]

You're getting confused

Low compression on a single cylinder means either the piston rings, valve seals, or the headgasket on that particular cylinder is going bad.

The pcv is causing your excessive crankcase pressure, which is a whole different problem itself. Are they related? Yes and No.
You need to replace the pcv with a known working one. This will not fix your problem. However it is a good possibility that the problem originated because of the bad pcv.