i have a chevy w3500 deisel box truck..basically a isuzu npr.whenever it is first started in the morning it blows light blue smoke for a few minutes..but the biggest problem is that when you step on the gas it whines like a belt and worst of all if you put the exhaust brake on and let off the gas it really whines but the exhaust brake still seems to work.although i do not leave it on because of the noise.i have tried disconnecting the exhaust brake which eliminates the exhuast brake noise obviously, but when you accelerate you still get the whining.even went as far to take the whole exhaust off and it still whined.turbocharger was looked at and it seems fine and ther is no loss in power...please help me with this aggravating noise....thank you whoever answers this for me....

tom kirk, May 2005

Dear Tom,
I had the same problem with my 2000 NPR. It was the exhaust manifold. It seems that the bolt closest to the radiator has a history of breaking off, then the manifold warps away from the block just enough to cause a whistle when the exhaust brake is on and creates back pressure.

Ron, April 2006