Proper Oil Catch Tank

The Dog has been having occasional heavy white smoke coming out of the exhaust since the turbo conversion. There could be some causes for this but i ruled out most of them already like worn piston rings or valve stem seals. What's left is the probability of inadequate oil drain line, bad turbo seals or clogged PCV line.

Since the smoking only happens occasionally and mostly during idling, bad turbo seals are unlikely as this usually happens even when cruising. What's left is now either inadequate oil drain line or clogged PCV line.

Being cheap, i used an old AC dryer bottle as my oil catch tank. Since i didn't plumb it back to the intake line, it's possible that this isn't enough to relieve the crankcase positive pressure and causing the oil not draining properly from the turbo and finally seeping out of the seals and smoking. Fortunately, i found a used Greddy oil catch tank replica at a bargain. I bought the tank and install it myself. Here it is in action.

It's not uncommon that PCV lines are run incorrectly after a turbo conversion. Most forgot that now their intake manifold will also see boost pressure and they didn't change the original PCV line. As far as i know, stock 4A-GE PCV line don't have any check valve. It just goes straight from the valve cover to the intake plenum. After a turbo conversion, you'd need at least a check valve there. You don't want any positive pressure from the boost to leak into your crankcase. This will blow your seals prematurely and, as i suspect it earlier, could cause improper oil drainage from the turbo.

If you don't want any check valve, at least you'll need to move the line going to the intake plenum to further upstream. This line should only see, at maximum, atmospheric pressure and this, on a turbocharged engine, can only be found at the compressor inlet. Thus my line goes from the valve cover straight to the catch tank and from there it goes to the compressor inlet, routing the line above the intercooler and no check valve necessary.

Did it solve the problem? Not completely but it's better now. I still have some smoke every now and then but it's noticeably less frequent. All there's left to do now is enlarge the oil drain line. It's annoying that i have to take off the oil pan just to do this but i guess there's no other way if i want to get rid off the smoke completely..