View Single Post
Old 10-13-2002, 11:25 AM   #24
Scooby Guru
Member#: 7089
Join Date: May 2001
Chapter/Region: NWIC
Location: Western Wa
2016 STi


You're right on Phil, that was my problem.

It sucks to have to admit what a dope I was, but it was my fault all along.

I thought it through again yesterday, and realized that could be my only possible problem. The crankcase was not being properly ventilated, causing some positive pressure buildup, preventing oil drain from the turbo.

I had the valve cover vents and crankcase vent all tee'd together, running into a catch can. Suction on the catch can was back to the induction pipe. The PCV valve was blanked off.

My thinking in this was that the induction pipe is better than a simple breather filter, as there's always a tiny bit of vacuum before the turbo. Even at an idle, there's a tiny bit of vacuum. Obviously, there is not as much vacuum in the induction pipe as there is in the intake manifold, but there is more vacuum in the induction pipe than I would get from a simple breather filter. I thought that as the amount of blow-by gasses introduced into the went up (due to throttle plate being open more), and the vacuum in the induction pipe gets stronger, it would be an ideal combination.

I was wrong, and my setup was flawed. There is just not enough vacuum in the induction pipe to pull the vapors from the crankcase to prevent pressurization of the crankcase.

I have now changed the suction on the catch can to mock the stock setup - the PCV valve and induction pipe are tee'd. Suction motive force at <101kpa manifold pressure is provided by the PCV valve, and suction force with positive manifold pressure is provided by the iduction pipe.

I picked up the VF29 Friday and dropped off the VF34 to be cleaned out. I put my car back together yesteday, and everything is good... except I feel like a dope. O'well.

All in all, it's a $250 mistake... cost me $125 to get the 29 cleaned out, and $125 to get the VF34 cleaned out. Live and learn.
* Registered users of the site do not see these ads.
Austin is offline   Reply With Quote