2002 Pontiac Grand Prix 3100 SFI
Engine makes a high pitched screeching sound when engine is revved.
The sound is coming from the left side (front) of the motor, where the belt runs.
When driving, the screeching occurs when accelerating to highway speeds, or when climbing slight grades, there also seems to be a loss of power.
Backing off the throttle will stop screeching, and you'll be driving like granny.
I thought it was the belt, or a belt driven accessory like tensioner or water pump.
With the hood open I removed the belt and did a quick test. When I revved up the motor it still screeched... NOT GOOD!!!
It runs smooth and quiet until I accelerate hard or try climbing a moderate grade.
If I drive like granny there's no problem!
What internal parts could be causing this?
Also... I pulled and inspected the PCV... it's clean and working fine.
There is no excessive internal vacuum or back pressure.
If I punch the throttle I can get a quick screech (just like a belt would make).
If I slowly increase throttle, it will run smooth until about 3500-4000rpm before it starts to sound off... and all this happens with the belt off???
