Oil dripping from breather tube on fresh rebuild.

Have you; broken in your motor loaded yet on a long run or just bobtail around?

 

If it's that bad, you've got major issues or a major oil leak. Possibly the rear cam cap?

If you're certain it's out of the blow by tube, it's gotta come back apart

 

That’s a lot of oil in 50mi. I’d be having a look at the compressor first, and anything else on the accessory drive. Gasket or o-ring on the compressor would be most likely, that’s a pretty big hole. Not real familiar with Detroits but I’ve had Cats try to empty themselves around a bad compressor o-ring. No dripping leak, but would fill the channel in horse collar under the transmission with oil in a week on the road.

 

I’ve had 60 series for over 20 years…. I’ve got a glider with a 97 model 12.7. I’ve had same issue for years with it. I’ve got similar oil pressures as you do. This past January I replaced the turbo and air compressor thinking it would help but it didn’t. I also had the crankcase filter removed and cleaned as per Detroit they say the part is obsolete and can’t order it. Mine never loses any oil while idling from breather tube. Only while driving…. Granted not as much as you’re losing but enough to get it on the front of my fuel tanks. So what I did about a month ago was buy a hose that extended my breather tube to about an inch from the ground and it helps. We have a thread about this very issue on here….. use the search box I don’t know how to link it here. @Rideandrepair may be helpful

 

IIRC there is a wiring harness that enters the right rear side of the head. I would wash the oil off and have someone sit in the truck and bring the RPMs up. If you're losing that much oil in 50 miles I would think you would see oil leaking somewhere.

 

Take it out and hammer the heck out of it

 

You say it’s losing 1/4 of the oil? 2-3 gallons in 50 miles? Or 1 quart? A fresh engine will push oil past the rings, and slobber oil out of the exhaust. Sometimes seeping out around the turbo clamp or anywhere it can. Are you sure it’s not going out the exhaust? You have a stack? Grass burner by chance? 2 gallons in 50 miles, that’s a lot of oil, no matter what.

 

Verify its actually coming out the blowby pipe and not anywhere else first.