2008 c15 engine brake

I have a 2008 c15, had the overhead done about two months ago. It originally went to the shop because of a ticking noise, which turned out to be a broken rocker stud and 4 loose ones. Replaced all nine.

Engine brake worked fine before, and for about three weeks after. Before the motor warms up, ( 5 or 10 miles), the engine brake works fine, then it gets extremely weak. Myself and several mechanics have run it with the valve cover off and energized the solenoids individually, and all three at once. They all work. They also function properly when you change the range selector switch. I changed the oil pressure relief solenoid, the pressure sensor, and the selector switch on the dash.

Just seems like once it warms up it doesn't hold oil pressure. Everybody says that the brake assembly is un-serviceable. Seems like there's got to be an O ring folded over somewhere or something, that can't hold the pressure once the oil is heated up.

Another guy says there are oil supply tubes that would have been removed with everything else when the studs were changed, and that these have O rings on them.

Anybody know whats up with this?

 

That's the first info I've gotten that makes any sense. I guess the one to start with would be the back one, which had the broken stud. Sometimes it will start working fine for a half mile or so and then act up again. I don't have a lot of internal engine experience, but would the shaft be a changeable part? I know you change one set of jakes. Or is the shaft tied into the jake assembly somehow?

 

Probably is cracked. I been told that's the next thing that happens after the stud breaks if you keep running it. Great. Another $1200.

 

Funny you mention those bolts. I'm trying a new mechanic, he was saying about those bolts and the oil supply hole last night. He's suppose to be working on it today. He'll be my hero if he fixes it. He's the third mechanic I've been to for this. I'm afraid to go to a dealer with it, they don't know anything anyhow. This guy only does motor work and is the exclusive motor guy for a few small fleets in my area. I'll post the outcome.