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Screeching sound, but not from belt

L

LeoD

New member
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 etc.
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?

Has anyone else had a similar problem?
 


Internal, you don't want to go there.

Might be a bad balancer, typically not a screech, but can be. Since you pulled the belt, that gets many other things out of the way. Might be a PCV malfuntioning.
 
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???
 
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Try running with the oil filler cap off. You may be getting to much vacuum built up in the motor and removing the cap will stop it.
 
I forgot to mention, I tried that too!
I'm thinking bearing, pushrod, or even a valve guide that's generating the noise ?
Whatever it is, it's not going to be fun!
 
Okay. On 3800 if your PCV vent line gets plugged it builds vacuum and the front seal squeals just like you describe.
 
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LeoD said:
I forgot to mention, I tried that too!
I'm thinking bearing, pushrod, or even a valve guide that's generating the noise ?
Whatever it is, it's not going to be fun!
Click to expand...

video plz

pushrods/ valve guides cant "screech" unless you press em against a chalkboard
 
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