1G Boost leak to valve cover?

[rdeis]

Howdy! I thought I had the boost leaks fixed, but it doesn't statically hold *all* the pressure, just most of it, so it's still leaking someplace, right?

TB gaskets are new, BISS screw is new, TB shaft seals are new, Injector seals are new. Hoses all tight, new PCV. EGR blocked off with a new gasket.
Using a mechanic's stethoscope I don't hear any air leaking from any of the usual places.

But I do seem to have air coming out of the valve cover breather? If I open the oil cap I definitely hear airflow sounds coming from in there.
Is there some other path for air to get into the valve cover? It can't be blow-by coming up from the crank, can it?

 

[jdxnc]

That's air leaking around your rings. You'll never get 100% seal on a BLT, it will always slowly leak down and have some coming past the rings.

 

[pauleyman]

Howdy! I thought I had the boost leaks fixed, but it doesn't statically hold *all* the pressure, just most of it, so it's still leaking someplace, right?

TB gaskets are new, BISS screw is new, TB shaft seals are new, Injector seals are new. Hoses all tight, new PCV. EGR blocked off with a new gasket.
Using a mechanic's stethoscope I don't hear any air leaking from any of the usual places.

But I do seem to have air coming out of the valve cover breather? If I open the oil cap I definitely hear airflow sounds coming from in there.
Is there some other path for air to get into the valve cover? It can't be blow-by coming up from the crank, can it?

Air past the rings goes into the crankcase. EVERYthing is now exposed. oil pan, valve cover etc. all part of crankcase. So short answer. Yes it will come out of the valve cover breather.

 

[DSMPT]

It's kinda normal that you hear the air from the oil filler cap or oil dip stick tube. It won't keep the pressure forever like Joson and Paul said above, the air is slightly escaping through intake valves to crankcase or/and exhaust. And also if you are applying the air to the turbo inlet, the air go to crankcase through turbo oil drain. So you may hear more air from the crankcase.

 

[steve]

Make sure your PCV actually seals when there is pressure on the manifold side. The valves I've seen/tested since the Mitsubishi stopped selling turbo DSM has pretty much all leaked and aftermarket ones almost 100% failed which isn't too surprising since most of the cars that use the same valve are NA and don't need to seal.

 

[rdeis]

Make sure your PCV actually seals when there is pressure on the manifold side. The valves I've seen/tested since the Mitsubishi stopped selling turbo DSM has pretty much all leaked and aftermarket ones almost 100% failed which isn't too surprising since most of the cars that use the same valve are NA and don't need to seal.

I tested the new one and it was "pretty good" but doesn't totally seal.

Is there a source for one that seals, or do I just accept that as normal?

That's air leaking around your rings. You'll never get 100% seal on a BLT, it will always slowly leak down and have some coming past the rings.

Good to know, thanks! so it will leak less when properly warmed up.

Yes, I normally test via the turbo inlet. I suppose I could test at the throttle body elbow as well to eliminate the drain line as a leak source...

Is there a rule of thumb I can use to judge whether the valve cover leakage is acceptable?

 

[steve]

I tested the new one and it was "pretty good" but doesn't totally seal.

Is there a source for one that seals, or do I just accept that as normal?

I haven't found a source that can be counted on. I keep testing and returning those that don't
Others put a check valve inline.