My wife's 95 Envoy (Trailblazer) with the 4.2 inline, had developed a whine that can be heard above the engine noise at anything over 1800 RPM. I thought it was the alternator and changed it...wasn't it. It's pretty loud and is the dominant sound in the engine. I've used a stethoscope and the back block is quiet. The alternator makes a whine but the new one made the same sound and it wasn't as loud as what we can hear. There is some whine on the front of the block where I assume the timing belts are. The power steering pump doesn't seem to be any louder than the front of the block.
I'm afraid it's the timing belts....
Appreciate your thoughts?
