Hello all, Recently I got my "85 Shelby back on the road with a fresh turbo and an upgrade to TII. I took it for a ride and much to my dismay when I got up to 11 PSI smoke started to poor out of my tailpipe and engine compartment. (I didn't have a pcv system hooked up) Thinking my turbo had problems I called Chris at TU and he helped me understand that blowby was preventing turbo oil from returning to the pan and forcing it out the turbo bearings. We cant have that now can we.
What to do, the car hadn't been using oil before and now it was very embarassing to have this problem. I realized that the open valve cover port was causing part of the problem and had to do something about the blowby. This isn't a good time to rebuild the engine but I thought I had a solution that would cost less than $20.00.
I took a metal tube that lots of turbo Dodges had and cut it off at an angle on one end and removed about a quarter inch of the other end. I got under the car and eyeballed where I would put it on the manifold pipe and outlined it with a magic marker. I then cut an oval hole in the pipe a few inches down from the turbo outlet. I got an ordinary 1/2 npt X 3/8 npt threaded black iron bushing and using my die grinder removed the internal threads to fit the pipe inside it. I welded the pipe inside the bushing and screwed on a check valve from a 1987 Chevrolet Caprice with a 307 "Y" engine. This is part of the air injection system and dosn't allow exhaust to flow back into the air injection system. I re-installed the manifold pipe with a length of 5/8 ID heater hose and screw clamp. I attched the other end to the emmisions outlet on the valve cover which has a straight outlet.
This created a pan evacuation system. It creates a vacuum because the flow of exhaust past the opening for the tube welded into the manifold pipe scavenges any air flowing out of the valve cover opening. The tailpipe is open so no significant positive pressure is created at the check valve. When the engine is running and you have the hose off the valve cover a very small pulse is felt at the hose. When you open the throttle very good negative pressure is felt.
There's nothing new about this system, fuel dragsters use it to scavenge high internal crankcase pressures and it helps with ring seal. I thought it would work but I wasn't sure.
I took the car out for a test and yippee, no more smoke. Additionally the engine seemed to idle smoother. Its not clear if this can cause problems down the line but at least for now I can avoid a rebuild which I dont have money or time for.
The pictures will tell the story and if you have the tools, its pretty easy to do.