hi i need some help. i did a boost leak test on my car today and as the air preessure guage got to 14psi i felt air comming out of the port on the side of the valve cover that returns to the turbo. my car has never smoked, the engine is brand new from the dealer with less than 10000 miles. i disconnected and pluged the hose from the intake manifold to the pcv and it is still doing this. what could possibly be causing boost pressure to enter the valve cover/crank case from the intake track. my car runs perfect no issues other than i believe i had a boost leak. thanks for any suggestions.

 

its going to get into the crank case because not all the valves are closed

how much air is coming out?

 

i have set timing to tdc were all the valves are closed and the guage will not read more than 14psi then testing because of the air leak at the valve cover. i did this same test 6 months ago and i was able to pressure the intake to 24psi with no problem and it held that number and then slowly went down. while driving my car reads 26psi on boost guage and pulls pretty hard.

 

setting it for TDC is setting cylinder #1 at TDC, there are still other valves open

 

thanks for replies jeri. i feel even if there are valves open there should not be any pressurized air in the valve cover. the valve stem seals should seal the pressurized air from the intake track from entering the valve cover/crank case area. i am going to do a leak down test tommorrow. but it is just odd because my car has never ever smoked. that air that is leaking out of the valve cover would be a big boost leak at 26psi if i can feel it leaking at 14psi.

 

Normal, just pinch the breather line off the cover when doing a boost leak test.

The air comes into the valve cover from the PCV not the valves.

 

i caped the line from the pcv to the intake to see if that was the problem and it still happened. i feel it has something to do with the pcv. i changed the pcv valve because the pcv is suppose to seal the valve cover from seeing manifold pressure under boost but i am still getting air out of the port. i feel 14psi in the valve cover/crank case is enough to cause seal failures in the motor.

 

Could have bad valve seal then.

 

rebirth of this thread. i'm having the same issue. any suggestions anyone?

 

I have the same issue and I believe it might be leaking around the pistons, pressurizing the crank case and then getting into the camshaft/valve cover area.

I didn't even notice it until I just recently fixed a huge boost leak off the EGR vacuum line. My boost would usually fall 2-3psi max to redline and after I fixed the leak it started to fall more like 5-6psi, almost like fixing the leak made the other (valve seal or piston) leak worse. I noticed my max boost shoot up by 4psi (31 to 35) after the EGR leak fix, but it seemed to keep the same boost out to redline (30ish). The spoolup seems faster now with more surge unfortunately.

I still need to cut off the recirc on the backside of the cover to see if it is comming from the valve seals or not, but I suspect it might just be leaking around the pistons, from cylinder wear. Hopefully she can hold together till next winter

Another thing to note, I can't even build pressure on a bike pump when the engine is cold, but after warming it up I can hit around 7-8psi and it will leak back down slowly. Of course I can hit higher than that with the compressor. Not sure if that points towards pistons or valve seals or if it could still be either.

 

my rings are fine though.

 

I can do another compression test, but I am still making 500+whp. Maybe that points towards valve seals hrmm.

Somebody with more experience will have to chime in. I am not sure if you can get boost leaking around your pistons and not have serious blowby. You would think the pressure of compression would be much greater than the pathetic 8-9psi I was putting into the cylinders, but there might be something I am not thinking of.

 

yea. i'm thinking the samething. I just put a new head gasket on, and had a valve job done. So something is fishy

 

Are you guys pressurizing it on the turbo or the t-body? If your connecting to the turbo, try the t-body.

 

I am pressurizing it on the turbo, are you suggesting the air is somehow getting into the turbo bearing/oil line? I have to admit, that I did do a test not too long ago at the pipe instead of the turbo and I don't remember that leak being an issue, hrmm. I will try it up top again and see what I get.

If it no longer leaks out of the valve cover, the turbo must be the issue. The turbo does have like 75k on it.