Dog Whistle in the Engine?
After my head gasket replacement I am noticing a new noise. When driving down the road, at 50-55 for example, if for some reason I have to roll on the gas, or I go up a little grade, I hear a VERY, VERY high pitched whistle from the right side of the truck. It is so high pitched it sounds like it is almost out of my hearing range.
When it happens I seem to notice that boost is around 4-6 psi usually.
Anyone else ever have this? I'm thinking a bad seal from the manifold to the up-pipe, or a cracked manifold?