Hello everybody,
One of our company trucks, a 2008 Resistol with the 6.7L, makes a horrible squealing sound when the exhaust brake comes on, between 2200 and 3000RPM... As soon as the exhaust brake disengages the sound immediately goes away... How does the exhaust brake on these trucks work? Is it a variable vane turbo or is there a gate valve of some kind? I don't wanna drive it like this... Anybody have any ideas? It only has 67000KM on it so it should still be under warranty...
Thanks!

 

Assuming it's an exhaust brake and not a compression brake I'd be looking for an exhaust manifold leak.

 

They have a ring that opens and closes, and yes that would be an exhaust leak. Check all the exhaust manifold bolts if you can get past the EGR stuff. Won't hurt it, just annoying to hear.

 

If its still with all the EGR stuff in place, there could be an exhaust leak at the EGR cooler or from the cooler servo connection. Either way its more likely a gasket or something small making all the noise.

 

Thanks for all the input fellas, took it in to get looked at, turns out it was indeed an exhaust leak. Thanks again!

 

Was it covered by the Cummins 100K warranty on the motor? I have the same problem....thanks for letting me know.

 

Yup it was. Only one gasket was leaking apparently but they replaced them all so I was pretty pleased with that.
Cheers!