LQ4 into a 3rd Gen/1972 Nova by frojoe

4 minute(s) of a 891 minute read

I have no idea.. cold oil pressure is 60psi and warming up to about 40-45psi depending where I set the idle... these turbos have spent a total of about 10mins at idle. Oil pressure has increased to mid-60's when warm at about 2500rpm the one time it was revved to that rpm and held there.. engine hasn't revved above that in its new configuration.

I'm trying to wrap my head around how this is possible.. I simply can't see how the -10AN turbo drain would be any restriction in its current form especially at idle, especially with "an oil restrictor" in place. The only thing that makes me second-guess myself is that the driver side (leaking) has 5/8" 0.043" stainless tube for the majority of the drain tube, however it's a minimum 30* downhill the whole way. The passenger side is -10AN Earl's UltraPro hose the whole way and didn't exhibit any signs of leaking. I was itching to dig into this yesterday but the engine didn't cool down enough before I had to leave the garage.

My plan of attack, in order of effectiveness is:
- don't touch any of the turbine housing bolts or CHRA... leave the current "leak" intact
- drain some oil to bring level down to "full" on dipstick (already done)
- undo turbo drain, use dulled aluminum filler rod to check for any obstruction, at same time inspect that turbo drain gasket isn't obstructing the drain flange.. re-attach drain
- restart engine, warm up, check for leak
- if leak is still present, remove CHRA+compressor from the turbine housing, leaving turbine housing attached on hotside/downpipe for convenience... visually inspect turbine wheel and axle shaft seal, inspect downpipe to see if oil has been blowing down it

EDIT:

Another thought I has was if this leaking oil is just assembly lube? I noticed that when I left the turbo's on their side in a box many months ago, there were some oil drips from what I presumed was axle/seal assembly lube, maybe after the turbo shaft had actually spun more than a couple rotations, some more assembly lube got flung out around the turbine housing & CHRA mating area. I didn't want to "stop" the leak by checking the tightness of the turbine housing cover bolts after this happened, but maybe they're allowing that assembly oil to drip out (although I didn't hear any exhaust leaks from the turbo).

Thanks for that info Clint, I'll read thru what Garrett has to say. I spent a good 5 minutes inspecting the turbo top and bottom sides as best I could with a flashlight and a pen mirror, since things were pretty damn hot still... I really couldn't see anything at all other than the drip in the pics, which to the best of my thinking appears like it is to be originating from underneath the turbine housing bolt head. It was impossible to take a pic of, but the top side of that bolt head between it and the underside of the CHRA was clean and dry, so I think that rules out oil dripping on to of the bolt head from the CHRA. The entire CHRA was dry as far as I could see..

I aim to go back out there one night soon and give it a closer inspection with it cold. Good call on pulling the compressor elbow off to inspect.