Thread: Boost in Crankcase?

I was pressure testing my intercooler piping and noticed my valve cover breather was letting air out. I plugged it up with a rubber hose and a socket, and continued on looking for leaks.

Pressurized the system to about 10 psi and I'm hearing it leaking again. I danced around a few couplers and re-tightened them, still there! Tried to feel where the air is coming from, turned out it was from the dip stick! Started removing the dip stick and a ton of pressure let out.

This doesn't seem normal at all, only guess is my piston rings are toast. The car was cold so they might have not been sealing properly too.

Sounds bad. How was the cars idle before you took her apart.

Idle is fine, with N1 cams on low lobes it still idles at 22-25 inHG. She has no problem idling at 750 rpm.

Now I do have another issue, which is with the OBD1 ECU it self. Every few tune uploads, or ecu reset, it forgets the TPS closed voltage, thus it idles at 2k rpm until the car is started 5 times or so. When this is happening, the TPS voltage is at .50 like it should be (as per Miko), but TPS closed flag is off.

Also I didn't really take her apart, the internals that is, just removed the SSAC header and installed the turbo mani. I will be doing a leak down test on Monday as I'm swapping the stock 20ve cams back in.

When you were checking for leaks was that hose on the intake pipe (turbo inlet)to the valve cover on or off.

It was off, I had my boost checker directly on the turbo. Oh man I think I know what it might be, a stuck PCV valve!

if there is a way for air to get in the engine, then you will pressurize the crankcase. Even on a fresh new OEM motor. The lowest leakdown motor I have ever tested came out at 4%. When you test for boost leaks I typically cap off the throttle body and the turbo inlet.

Capping the TB would be optimal, but wouldn't test any leaks in the intake manifold. Now last year with my T3 setup, when I did a boost leak test I got 23 psi no problem, it was to the point that the turbo comp housing was leaking.

For how much pressure I was seeing in the crank case, I either have a hole in a piston, or non-existent piston rings, or finally the PVC is dead. Last time (couple months ago) I did a comp test it checked out at 210 psi on all 4, so I am really starting to think the PVC is just stuck.

I always cap the TB and check for vacuum leaks once the boost checks out good. It is pretty easy to hear a vacuum leak, or to spray around for it.

Yea, the pcv could cause that to happen. So I wouldn't fret too much if the motor doesn't burn any oil. If you had a hole in the piston, or bad rings, you would have smoke out the exhaust for sure.

Of course, my motor ran strong as hell on 90psi compression on 2 cylinders. You remember that? 2 pistons had holes in them. That motor smoked, but just barely. You couldn't tell except on a cold start. I never saw any smoke behind me, but I did notice some smoke at idle on a cold start.

I bet all is good. But that's me.

If your pressurizing the motor as well are you making sure that all intake valves are closed during the pressure test. Cuz usually at least one intake valve will be somewhat open anywhere on the cranks location. So all your getting is pressure past the rings which is normal Its never going to seal completely.

Definitely dont want to pressurize your crankcase too much as you will blow out the oil pan gasket sealant.

im not so sure about this one...