I have a 2003 Bluebird Skoolie 5.9 Cummins / Allison 545 conversion that I use for living in on road jobs. Today as I was coming up to Farmington from Albuquerque. On an uphill grade I heard a "pop" and then an air leak. My air brake system is good, it only hisses when the engine is under load. Down hill it is barely noticeable. When I stopped to check it, the filter clog indicator had come apart so I put a cap on it until I can get a replacement. The leak is still active... I checked the pressure side of the turbo for a bad relief valve but couldn't find any. When Vehicles pass me on the left I can hear a pft pft pft kind of noise reflecting off the cars... It is definitely an air leak, has to be associated with the turbo because it changes with load on the engine. Everything seems to be running ok... Any ideas here?

 

Sounds like you had a turbo duct failure either from the turbo to the intercooler or intercooler to the intake manifold. Check these carefully as the blowout could hide.
Back to morning brew . . .

 

That's what I was thinking... I checked initially and didn't see anything... I'll take off the expansion joints and the ducts and check more carefully. Thanks, Jimmy

 

It turned out to be the suction hose on the Air Compressor.