Truck bought for parts, got it running, but…

[Mogman]

Any other words of wisdom for turbo oil leak at the base?
Have you seen this issue before?
Is the torque maybe too much or too low?

I have not, I torque them to 35lb

 

[mccullek]

Ok, so I finally got around to install the new turbo cartridge, new gaskets, new turbo bolts, unblocked the wastegate (it is moving smoothly now), but there is not much change. The blow-by is the same and it still leaks oil at the turbo base, maybe less than before.
I tightened the two turbo bolts little by little alternating from each side to about 30 ft-lbs as there is no torque info in the manual.
In one GM manual I found it says 33 to 44 ft-lb and on the flashoffroad site it says "Turbocharger Mount Bolts 43 ft-lb".
I have another set of bolts and another seal to try, has anyone dealt with a similar oil leak like this before?

One thing about many of these machines is that they sat around for a long time before they were actually auctioned off. Normally when you run them a bit the rings reset and the blow-by improves. Not sure how much you have run yours now, but assuming you have had it a while since this thread is older.

I would get all of your leaks corrected and then do an oil change and ditch the synthetics. I am not sure how much truth there is to it, but I have heard that synthetic oil tends to create more leaks, so an oil change using regular 15W/40 diesel oil might help with the leaks and rings. I had some blowback in both of mine, but no leaks. I used Valvoline Premium Blue HD Conventional Diesel Oil 15w-40 in mine, and it runs well, no leaks and the blow back is all gone now. I specifically did not put the synthetic in it because I was told it was more prone to drips and leaks in older diesels, although I put it in all my personal vehicles. Again, I am not sure how valid that claim is about the diesel leaks, but I have heard it many times. Mine purrs on the regular Valvoline 15W-40, so it seems to be a good choice.

 

[Mogman]

Ok, so I finally got around to install the new turbo cartridge, new gaskets, new turbo bolts, unblocked the wastegate (it is moving smoothly now), but there is not much change. The blow-by is the same and it still leaks oil at the turbo base, maybe less than before.
I tightened the two turbo bolts little by little alternating from each side to about 30 ft-lbs as there is no torque info in the manual.
In one GM manual I found it says 33 to 44 ft-lb and on the flashoffroad site it says "Turbocharger Mount Bolts 43 ft-lb".
I have another set of bolts and another seal to try, has anyone dealt with a similar oil leak like this before?

Did you inspect the mounting surface for the turbo and the turbo itself very carefully?
Any damage, dings etc. could cause your issue, even thought there is no valid reason to run synthetic oil in a Detroit I don't think that would be your issue here.
It is a very simple setup as far as the seal goes but any damage to the mounting surfaces can cause an issue.
For example any dent in the circumference of the machined surface for the turbo mount can hold the surfaces apart

 

[T9000]

Did you inspect the mounting surface for the turbo and the turbo itself very carefully?
Any damage, dings etc. could cause your issue, even thought there is no valid reason to run synthetic oil in a Detroit I don't think that would be your issue here.
It is a very simple setup as far as the seal goes but any damage to the mounting surfaces can cause an

Yes, I took a close look and one thing that doesn't look right is that the small side of the snowman seal seats lower than the larger side, almost level with the engine block edge, giving the feeling that there is very little to no compression present when the turbo cartridge is installed. I ignored it thinking that it would be very unlikely for it to be machined wrong, but I will take it apart again and try to use a second seal, sliced longitudinally to make it thinner and see if the leak stops with a fatter seal. I think I have a way to remove just the cartridge without removing the whole turbo assembly. Here is all put together, looks a lot better than when I got the truck:




EDIT: BTW, the engine starts right away, even as it sat with the turbo removed for months (I sealed all openings) and it sounds very buttery, which overall is a good sign.

 

[T9000]

Good news! It turns out that when I installed the turbo assembly the first time, with the crossover attached, I pushed out the snowman seal (found it in the engine valley), I guess when was trying to fit the crossover under the body. This time, after learning the turbo inside and out, I removed just the cartridge and saw the missing seal:






I attached just the cartridge and ran the engine without the wastegate assembly and the leak stopped. I am about to put everything back together and take it for a ride, see what happens.



Once the leaks are fixed, everything is closed and sealed, will clean the rest of the engine.

EDIT: On both sides of the crossover I added NPT fittings, which have pressure and IAT sensors for now, to dial in the wastegate spring boost (IAT is for a different purpose, not related to the boost setup):

 

[T9000]

One thing about many of these machines is that they sat around for a long time before they were actually auctioned off. Normally when you run them a bit the rings reset and the blow-by improves. Not sure how much you have run yours now, but assuming you have had it a while since this thread is older.

I would get all of your leaks corrected and then do an oil change and ditch the synthetics. I am not sure how much truth there is to it, but I have heard that synthetic oil tends to create more leaks, so an oil change using regular 15W/40 diesel oil might help with the leaks and rings. I had some blowback in both of mine, but no leaks. I used Valvoline Premium Blue HD Conventional Diesel Oil 15w-40 in mine, and it runs well, no leaks and the blow back is all gone now. I specifically did not put the synthetic in it because I was told it was more prone to drips and leaks in older diesels, although I put it in all my personal vehicles. Again, I am not sure how valid that claim is about the diesel leaks, but I have heard it many times. Mine purrs on the regular Valvoline 15W-40, so it seems to be a good choice.

Just a quick update, I fixed all the oil leaks (so far it looks good) and replaced the synthetic Shell Rotella T6 with conventional 15W-40 (couldn't find Valvoline HD in my area and got Chevron Delo 400 SDE HD). I run Rotella T6 on my other HMMWV (same 6.5TD engine) with zero blowby and no leaks or issues and really didn't expect any dramatic change, but did it just to eliminate any potential variable and have a baseline.
When I re-started the engine the blowby was much lower than before, but after driving it around for a few minutes it came back stronger, like it was before changing the oil. Will keep an eye on it and see if it improves. Otherwise the engine sounds and runs great.

EDIT: I have one other issue to figure out, being that when I drive it for a few minutes something gets very hot and some white smoke, steam like is coming from somewhere under thru the opened doghouse.
I stopped it right away and couldn't see exactly where it is coming from, initially I thought it was the leaking oil that was burning on the exhaust pipe and manifolds, but it is still doing it after I cleaned the oil. It almost smells like burned plastic but not exactly. It was smelling like burnt oil before fixing the leaks but this smell is somewhat different. Still investigating.

 

[TOBASH]

Have you pressure tested each cylinder? That would answer a great many questions all at once.

 

[T9000]

Have you pressure tested each cylinder? That would answer a great many questions all at once.

Not yet, tried the easier things first and that would be next, looking to get a testing kit.