740 tic burning oil

So I?ve been having this issue for a while. Rebuilt engine, rebuilt 20t turbo, new valve stem seals, etc etc and can?t seem to solve the issue. Car runs great and boosts around 14psi no issues, but when idling hot it chucks some serious clouds. If I hold it around 1500 rpm the smoking stops. It does not burn any oil at all while driving or under load, only at idle/ under 1500 rpm. Occasionally I?ll come to a stop light and it won?t burn anything when idling, then the next light it will. When I rebuilt the turbo (due to the smoking), I noticed that the rear oil seal had a small chip in it. Oil burning seemed to go away for a couple hundred miles- then the car sat about a month or so. Just finished my manual swap today and the oil burning is back.

If it happens when the car is hot, it's probably from the chipped seal expanding with heat. Enough to allow it to leak at low pressures. But also make sure your catalytic converter isn't badly plugged. I recently learned that can make your turbo spit oil clouds at low RPMs.

Well that?s what I figured, except I replaced the seal/ bearings when I rebuilt it. The car has a 2.5 inch exhaust with no cat, the oil burning was gone for the 200-300 miles I drove it between the time I rebuilt the turbo and the time my automatic tranny died.

Are you sure it's not steam from a bad head gasket? I've had that happen, when you're driving down the road the pressure in the cylinders escapes into the cooling system and overpressures it, then when you return to idle the overpressurized cooling system pumps water into the cylinders and it comes out the tail pipe

It?s not steam either. Couple thousand miles on a rebuilt engine with a new head gasket, cooling system holds pressure when tested and no coolant loss. The smoke is thick and blue, and reeks of oil.

What do your spark plugs look like? Clean/put a fresh set in and read them.

Do you have oil in your intercooler?

Have you checked your PCV system?

That can help you isolate where the oil is coming from.

When you rebuild your engine, did you check your valve stems for wear?
New seals aren't enough if the valves are moving around too much.

Just pulled my plugs tonight all 4 were in good shape, no oily buildup or anything like that. Intercooler has a slight coating of oil but it?s been used on quite a few different setups of mine without cleaning. There wasn?t any oil on the compressor side of the turbo. Will check shaft play tomorrow night but should be within spec, only 500 miles on the rebuild now. Pcv box, drain tube, and O ring are new, I pulled it off and checked it, there was no sludge but definitely has had oil inside it and there was a little oil in the hose going to the intake. Valve stems were checked and within spec when the rebuild was done. What really confuses me now- I just put my muffler on a couple days ago and it looks like the smoking has stopped. I was running it straightpiped before when it was smoking oil. Have about 300 miles now with the muffler on and still no oil. Any insight as to why this may be? Gazebo effect?

were the straight pipes installed before the rebuild? maybe it was old oil burning out of the exhaust pipes? not usually the case without a cat...

Yep it was straight piped before the rebuild. Old oil shouldn?t take 1000 miles to burn off though

how is your pvc hooked up? I have to put a catch can on mine or it would puff some smoke. Also hows your drain on you turbo? I just recently did +T on my sons car and it would blow smoke. It ended up being my drain setup.

Pcv is set up as stock, brand new box, o ring, drain tube, and line running to intake before the turbo for vacuum. I?m running either 10 or 12 an line with a 3/4 not fitting tapped into my block above the pan. Line is as vertical as I can get it.