12.7 Detroit backfires and throws fireballs

Flipp: problem with the C15 is still unknown. Engine is currently being rebuilt as the head is cracked in 3 places.

It is understandable how frustrating it can be trying to chase down problems and not even the Cat mechanics can find it. The computer says it’s running fine. Even brought a loaded trailer in for the test, drove for over an hour, when the problem shows up, it’s not showing on the Cat Et.

So basically, we are at the throw parts at it stage.

First we will see if the rebuild with a new head fixes the problem.

 

im pretty sure the fact that the timing was off 1 tooth is ur reason, that always causes some sort of damage

 

Flipp: any luck so far to solving the issue?

 

i think it would depend on the severity of the bent valves, i came across a 60 that was two teeth off and it did run like crap and was sending pieces of valves through the exhaust, so one tooth it could still run, other than that it might just be an issue within the ecm

 

When mine was overhauled, they found marks on 3 of the pistons from valves hitting. Don’t know for sure if or how bad the valves were bent. It wasn’t visible. They were probably that way for a while though. It ran good, up until I blew an injector, and eventually cracked the head. An Engineer from Detroit said it was probably caused by worn valve guides. Same mechanic found cam gear 1 tooth off on a friends 12.7, after he had bull gear done. Valves were bent, had to replace the head. I’m just guessing that the tolerances are so close, that a bent valve is possible.

 

Hey Flip you ever find your problem. I have the same issue. Driving me crazy..