Here we go again... 6nz problems

Extremely bad exhaust valve guide. Saw that on a reman head once, it did not make 20,000. That was one mad commission mechanic.

 

I have seen the exhaust guides give up too CAT had a problem with that while back it was supposed to be fixed. Won't be any doubt when you pull the covers and see one spring looks like oil is cooked to it and the rest are clean. You can also really feel it if you shake it side to side

 

It's possible. You've got about 120 psi trying to push pass the compressor rings when you're approaching cut out. Never had to check for that issue before. I'm sure someone will correct me if I'm wrong but in my mind it would make sense to remove the discharge line from the compressor and run the engine. If excessive blowby is gone with discharge line removed and comes back with it connected, I'd say that's the issue. If it persists, keep looking for the cause.

 

Yea it will have too come off. Not sure if warranty will replace the head or just fix its issue. Seen it both ways.

 

Try not to fixate on any one thing mentioned. Could be any one of the things mentioned, till it's looked at its hard to say. After idling a while when you first pull out especially loaded do you smell oil burning almost like a small leak onto the exhaust