I'm still trying to decide between a couple of different options.
First I have to solve an oil leak problem I'm having with my front 368 - around the center section. (big clamp area) Already pulled the turbo and had it "freshened up"/checked out - still leaking under higher boost ..... we've been chasing this problem for several months now. Car seems to run fine but oil is leaking down/burning on downpipe - cause for concern ....
I've never heard of anyone having a problem quiet like this?
It's a long story - all the things we have tried / thought it could be.
We started out addressing the drain tube since oil was first seen running down that tube. On my 1st gen we had to fabricate the front mount and it resides very close to the downtube.
We did several things to widen the distance between the two - in case contact was being made under WOT / during engine flexing/movement.
When that didn't work (after two or three different changes/mods) we started taking things apart and found the oil appeared to be coming from the center coupling section that connects the turbine side to the compressor side - where the large coupling ring is. We pulled the turbo and found that my thrust bearing was a little loose. (not bad)
We sent it out, had the bearing replaced. Couldn't find anything major wrong mechanically but there was oil in the turbine side. Replaced one seal [just in case - no problem found] with a larger - after a little machining, put it back on - still leaks. The turbo shop suspected high crankcase pressure so I proceeded to route the drivers side front valve cover crankcase hose to my catch can and also connected an additional vac source (2nd intake (pre turbo) to provide additional crankcase pressure release .....
It still leaks.
My plugs look pretty good - not anything unusual there, fairly new rebuild (about 5K) - same Ross pistons, bore etc as you have - using alc injection - wonder if that has anything to do with it ......
I am left to speculate until my motor builder gets back from SEMA ... we'll find out sooner or later - hopefully sooner.
After reading this info it looks like we may have to go back and look at the drain tube again:
Problems with the oil drain system can cause leaks to appear in the turbo. When oil leaks appear at the turbine outlet, it usually indicates a problem in the oil drain system. Something has caused the oily foam to build up in the bearing housing to a height above the seals. Check the following items and correct them to eliminate the problem. Make certain that the turbo drain port is pointing down at not more than a 35 degree swing on either side of a vertical centerline. See that the oil drain line slopes downward its entire length, so that there is no place for the oil to collect inside of the oil line. Especially on new installations, the line should be closely checked and any "sink" traps eliminated. Make sure that the turbocharger drain is connected to some unrestricted place on the engine above the level of the oil in the crankcase. If the oil drain enters the crankcase below the oil level, it will cause the foamy oil to back up in the drain line and the bearing housing sump which will cause a leak.
With the 368 being in a different position than the stock turbo - it's possible the drain angle has changed enough to be causing my problems?
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