Quick question about turbo oil drain

[supraguy@aol]

My '88 project began having an Issue with serious, SERIOUS oil burning.
I have a brand new, fully built 7MGTE, zero miles. Car had been started a dozen times, and driven only twice, for a total of about 1/2 mile, to load the piston rings.
Later, it began developing the oil burn issue. At first, I was afraid that the cylinder walls had glazed over, causing blowby. I later took off the turbo, and found that loads of oil was leaking out of its seals.
This is a brand new, never run Precision 6266, journal bearing turbo:

My question is, of course, why did this happen? How was I forcing oil out past the seals?
The front and rear seals both look great, but there was obvious leakage past them(including a slight amount from the front seal. The obvious choices are:

Excessive oil feed pressure/ volume
Insufficient drain size/ bad drain angle
Excessive blowby gasses, backing up the drain

Precision doesn't call for any use of a feed restrictor, But once the oil burn started, I installed a .065" restrictor, as some people had reported using online.
No change. My feed size is 4an. Some people had suggested using a 3an, so I've ordered a replacement.

My drain location is the stock location, using a 10an line and an Arizona performance 10an block fitting.
I checked the condition of the line, and it's completely clear, no kinks. Here is a pic of the angle.
To me, it seems to mimic the stock line:

As for pvc blowby, I don't know. I could try a leakdown test, but just wanted to see if anyone saw anything that they would do differently.
Thanks for looking

 

[GC89]

What does the oil feed look like? Any type of restrictor?

 

[black89t]

if it leaked that much oil driving a half mile i bet you got one the many pt turbos that just fail. seen many leak in under 1000 miles. there quality control doesn't seem that good. i personally know a couple people that have had that happen. part of the reason i got a brogwarner turbo.

your oil feed and drain are just what it calls for. basically all journal bearing turbo require the same. and 7m's don't really have that high oil pressure compared to most motors so doubt thats the problem. also doubt its blow by. the crank case pressure when under boost say over 20 or 30psi is much higher and properly functioning turbos don't push oil past the seals.

id try not to idle the car too much either unless you're doing a cam breakin. get a load on it to seat those rings!

 

[supraguy@aol]

Yeah, still not sure what the issue is.
@GC89- The feed line was a 4an, now going to a 3an. Also added a .065" restrictor, but that's the smallest ever recommended for journal turbos.

 

[sheedy126]

The drain line doesn't look bad, but it does taper flat before it gets to the block.

I had a similar issue on my 7m, also rebuilt but under 10k miles. It was a hx35 with a - 10 to the factory location.

Burnt oil out the ass so I tried to redo the drain line for a more sloped angle. Same issue...

I then switched to a - 12 drain straight to the pan, turbo being rebuilt of course, I now have no issues at all

Before:

After :

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[MarkIII4Me]

^
Where in the pan did you run the drain line? Did you use the factory oil cooler return location? I was always afraid that would be below the oil line, but not sure how much oil would have to be in the system to go up that high. I've had my turbo rebuilt (no oil present on turbine when pulled) and still have smoking at decel (some oil out of the compressor too). -3AN feed line and -10AN drain to factory location. No blowby whatsoever. Also, do the turbo's seal get blown from this and need a rebuild, or will relocating the line (assuming that is the issue) keep the oil from pushing past the rings without a need for new seals.

 

[sheedy126]

You know I'm not sure if the seals need replaced when oil starts getting past the seal ring. Mine smoked for awhile so I had it rebuilt anyway

My drain line goes where the factory oil cooler line went, since I'm using a relocated oil cooler, thermostat, and filter. No issues so far but I also don't run my oil a quart over full like some recommend.

You may try fitting the new drain line first, then go from there. It'll be cheaper than having the turbo rebuilt as well

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[MarkIII4Me]

Did you have to tap the existing hole in the pan to accommodate the -12an fitting or did you weld in a bung? Looks tapped to me. Problem is, I don't want to drop my pan if I don't have to so I was wondering if I could tap it while it was still installed. If memory serves correct, the factory drain had a plastic bung installed in the pan. If I drilled that out, I doubt there'd be enough material left to seal at the threads of the new -12AN fitting. To the point, can this be done without removing the pan?

Do you really think that the relocation of the line and switching to a larger diameter drain resolved your issue, or was it maybe the new seals you had installed during the rebuild? Your -10AN drain line looks about as perfect as I've seen. Mine unfortunately has a 90 deg fitting right off of the turbo (exactly like the OP's), but it was the only way I could make it work. I tried going -12AN to the factory location, but it wasn't possible, as the fittings were so large that they would touch each other. No room to put a line in between.

 

[sheedy126]

Did you have to tap the existing hole in the pan to accommodate the -12an fitting or did you weld in a bung? Looks tapped to me. Problem is, I don't want to drop my pan if I don't have to so I was wondering if I could tap it while it was still installed. If memory serves correct, the factory drain had a plastic bung installed in the pan. If I drilled that out, I doubt there'd be enough material left to seal at the threads of the new -12AN fitting. To the point, can this be done without removing the pan?

Do you really think that the relocation of the line and switching to a larger diameter drain resolved your issue, or was it maybe the new seals you had installed during the rebuild? Your -10AN drain line looks about as perfect as I've seen. Mine unfortunately has a 90 deg fitting right off of the turbo (exactly like the OP's), but it was the only way I could make it work. I tried going -12AN to the factory location, but it wasn't possible, as the fittings were so large that they would touch each other. No room to put a line in between.

It's drilled out to 3/4" and tig welded the bung in place. I don't think it's possible to weld one in with the pan in place, but heck it might be

If I didn't have the turbo rebuilt because of oil blowing by the seals before I switched to the - 12 drain, I don't think it would have stopped smoking. It had quite a bit of oil coked up inside which is bad.

I definitely think fitting the - 12 drain to the block fixed my issue.

Originally when I first got the holset installed I had a - 10 going to the factory location. It started smoking bad. Upon further investigation, the drain line was kinked so I sent the turbo off for a service/new seal. I also put a new drain line on, the one first pictured. Was fine for just a little, then same issue. Smoke.

After that, I sent the turbo off yet again for service/new seal. This time I went with the - 12 to the block. Got the freshly serviced turbo installed, and no smoke! I think the drain line fixed the issue in my case, and may be a contribution in your setup too

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[supraguy@aol]

Thanks for your input, guys. Upon disassembly, the front and rear seal rings look great, but I went ahead and ordered a rebuild kit for it, regardless. I will be fitting a transparent -10 silicone drain, and playing with the length to get the best angle I can, to the stock drain location. What I can't understand, is how the stock turbo drain isn't exactly vertical, and is actually corrugated(!), and yet has no oil burn issues. Maybe it is pcv pressure after all. I'll post pics once I reinstall.

 

[hvyman]

I would go to the pan instead of using the stock drain on the block. -10 should be plenty.

 

[supraguy@aol]

I would agree, but going to the pan requires me to remove the pan for welding. And since it is the stock location, and a better drain than stock, I don't see why I would have to
change drain location. Since there's no deadline on this repair, I'm willing to try a lazy repair first, before trying to modify.

 

[supraguy@aol]

Upon further reflection, I am thinking that part of the issue may be the manifold itself.
My HKS knockoff sits the turbo lower than stock, and I think that directly affects the height/angle of the drain line. This is probably aggravating the situation.

 

[MarkIII4Me]

I can't help but think that the design of the factory drain is the culprit. If you look at where the drain feeds into the block, the oil will hit a wall before it drains down a hole in the bottom.



I assume that this wall works as some kind of baffle, but if you have a lot of oil volume flowing down, I can see this causing a major backup in flow. Looks like draining to pan is the way to go. I'm in the same boat you are at the moment and don't feel like pulling the pan to have it welded.

 

[supraguy@aol]

Agreed- Not a great design as far as flow rate goes, but I just can't see my aftermarket turbo flow any more than stock, especially with an inline restrictor.
And I already have to pull the pan on my 89...I don't wanna do the one on the '88 as well!