My cousin down in Texas is having problems with an 05 w 320k that turbo failed. heres info:
2005 cummins 3/4 ton Same truck I replaced the turbo on. Just flushed the intercooler spotless, drove it about 20 miles and she just died. I'm gonna explain what's going on. Every detail. Someone may recognize the problem.

Truck is completely stock and well taken care of. My cousins dad bought it new.

320,000 miles now.

Turbo shelled out last week merging on the highway with a small trailer behind it.

I told him to check the oil and drive it home. 10 miles.

I bought another stock turbo and put it on.

With the filter off, (in case runoff) I test drove it 10 miles. White smoke like crazy. Seemed like it was burning off the oil that leaked out of the turbo from limping it home.

Seemed normal. All the sudden I lost oil pressure. I shut it down and pulled over instantly.

Pan was dry.... Bottom of truck was covered in oil. And as I was driving, it was idling at 1500 rpms. Like the intercooler was full of oil...

So I fill it back up with oil, drive back to his house really easy and checked the oil. It hadn't dropped.

So I pulled the cooler off and flushed it out. Had maybe 2 quarts of oil in it.

Put it back on and let it idle for 30 min. (Idled real rough around 600 rpms. But wasn't dripping oil from anywhere. Oil lines on the turbo are bone dry, not a drip.

No white smoke either.

So I test drive it. Oil level is perfect. Btw.

White smoke when you accelerate hard and will stay at 2200 rpms on its own. Like its still burning its own oil. Then about 10 miles it ran great for about 1/8 mile. Like it wasn't burning oil anymore.

Pulled over and checked the oil. Barely on the stick?!

So we pulled it back to his house.

The bottom of the truck is covered with oil. Head gasket is relatively dry, water level is good and it's clear...

What do y'all think?

 

Is the replacment turbo new or used? If used are you sure its good?

Oil underneath is probably coming from the breather tube due to too much crankcase pressure. When my turbo went it pushed compression into the oil drain line and pressurized the crankcase.

Bad/broken piston rigs or a blown head gasket can also pressurize the crankcase.

Take the oil cap off while running, how much exhaust is coming out the cap?

 

Good points by Clay and I would agree that the replacement turbo is failing.

I would not run the engine while oil is getting into the intercooler. The engine could runaway on the oil.

Have you checked the turbo oil drain? Make sure oil is draining freely with no blockage nor kinks in the drain line.
If the turbo oil drain line is ok, I recommend to pull the replacement turbo and check it out.