Detroit series 60 12.7 oil out of breather

Sounds like the engine has a lot of wear. That's what the blow by hose is for. It let air pressure out that blows by the engine rings. You can have a blow by test and they can measure the pressure coming out the blow by hose. From that they can tell you if it time for a rebuild.

It usually blows oil even at ilde also. but lack or power and lots of oil coming out blow-by hose. Sounds like it time for a rebuild

 

Save your money on the test Lol. I think you’ve covered that. Excessive crankcase pressure can also be caused by a bad air compressor or a bad turbo. Rule those two out before signing up for an overhaul

 

I would suspect Turbo as it’s worse under a Load And is losing power. Maybe a mechanic with more knowledge than I can help.

 

How many miles on engine? If truck had 90,000 a year put on, then its at well over 1 mil. miles. Probably been rebuilt, but things don't last forever.

 

Movement of shaft is normal as long as it’s not scraping sides. But I’ve heard the seals can go bad and pressurize oil system.Dont know much more. Or how to check it. But that amount of blow by all of a sudden is definately serious. I wouldn’t run it much meanwhile.

 

Well not huge miles. Have you owned or drove the truck long? Anyway that is a lot of oil pushing out the breather. Would get it into shop and hopefully talk to someone knowledgeable. Compare new turbo price to dyno test and all. May not be a whole bunch more money to put a new or rebuilt turbo on and try that. If thats not the solution, at least you have a low mile turbo. Then i probably see a rebuild in your future. Unless air compressor. Actually in my over 40 years never had a turbo or air compressor do what your describing. Not saying it couldn't . When engines breath hard out the breather, its a rebuild.