Hi everyone, having a problem with my PCV system. Opening the oil fill cap results in air pumping out. I hooked up a low pressure gauge at the dipstick tube. At idle there is basically no vacuum or pressure ( less than + 1/2 inches of water or .018 psi) Giving a little gas but not yet getting into boost I saw up to around +5 inches of water or .18 psi.

Posted a similar thread on turbobricks but would like any help that I can get.
http://forums.turbobricks.com/showthread.php?t=331949

Some relevant information:
Stock 1988 745 turbo, ~250,000 miles, max boost at 10psi, b230ft engine. Compression check around 30k miles ago showed 15-25 psi increase wet versus dry on a warm motor. Replaced breather box/oil separator ~30,000 miles ago, running synthetic oil for the last ~10,000 miles.

Also recently set up a catch can set up as follows. Two 15mm lines coming off the stock breather box and one 15mm hose off of where the block mount distributor plug is -> to the catch can -> 15mm hose going from the catch can to the pre turbo intake hose and small vacuum line to intake manifold.

I will be checking for blockage in the breather box drain hose as a possible cause.
Could a blocked turbo oil drain also increase crank case pressure?
Or does the above sound like I have too much blowby due to piston rings?

Thanks for any help/ideas and sorry for the long post.