Cat c16 low power after cat dealer rebuild.

How long ago? Approx how many miles on build? Same injectors? How big of a rebuild.

 

I'm sure you took it back to them first and they said nothing wrong, but hold their feet to the fire you drove it before and after it should be the same. Don't let them sell you the old it's new and tighter snake oil story to get it out of warranty or at least till it blows a hose and logs a over temp event and vboids warranty. If a motor is to tight when built it will run hot be harder to start esp. when at operating temp, which it will reach quickly. They will run as good with 100 miles on them as 500000 if they are right. It could be as simple as a CAC problem to a major issue with out looking touching feeling or at least a little more info I wouldn't wanna throw alot out. Keep in mind even at dealers there are new guys we all have to learn we all need to start somewhere, course there are butchers that constantly change jobs before there crap catches up to them too. Most common thing i found is a 1\4 in pipe plug on bottom of head directly under where cac elbow bolts up is left out creates a leak, reman heads are sent naked if assembled on pallet there no way to see it. Like I said It could be endless possibilities its there responsibility they took your money, you took it there to get it done right you shouldn't have spend thousands more replacing parts that are good

 

Is it whistling when you get in the throttle, and building RPM really slow, any black smoke at all what is eng serial number

 

Sounds to me like they might have turned a new set of numbers into the ecm w/o your approval. I used to have a 3406E 475 that would oupull stock 600's. Originally, it wouldn't blow its nose. Pulled like crap. Told Cat they could have it back if it couldn't do better than what it was and the Cat Dealer put in a new set of numbers and it was like night and day. Took 'em just a few minutes. Nothing I ever ran across w/ pull with it. I'd certainly check that out before spending lots of time and $$$ in chasing a ghost.

 

Sounds like a low nox tune was put on.

 

All c16 files are low NOx files I believe.