Arg, I was hoping I could join these boards on a lighter note, but I think I may have a spun bearing on my 2000 WS6. When I purchased the car, I took it to a Pontiac dealership and had them do the 100-point inspection or whatever.. he took me outside to show me everything about the car. I asked him what this squeaking sound was from underneath the car... (you can only hear it from underneath... and the top of the motor sounds beautiful--nothing out of the ordinary.)

Well the mechanic, (and actually two of his co-workers, whom owned either an SS or WS6 for several years... both 2000s actually, said that for sure it was my A/C tensioner and/or idler pulley.

Well it sounds just like a tensioner going bad. Basically a metallic scraping sound coming from right near the bottom of the motor. Goes exactly with the RPM of the motor.

If I determine that it's coming out of the motor, is it possible that the balancer/crank pulley is what is causing the sound, or would it HAVE to be an internal bearing?

Thanks in advance!

-Steven

 

This is an easy one. Pull both belts and start the motor. If the sound is still there then you have an internal mechanical problem. If the sound isn't there when the belts are off then it's indeed one of the rotating accessories, pullies, or tensioners.
Had a terrible sound like that on the wifes GTP and it was an adjuster idler pulley.

 

Took the words out of my mouth. Also, after you yank the belts, turn each pulley by hand and see how they sound/feel....

I doubt a spun bearing would sound like metal grinding....

 

Rod bearings sound like a deep thunk, thunk, thunk. You won't hear any scraping or grinding noises. Sometimes a spun rod will also having a tapping noise to it, but that's usually the piston lightly hitting a valve and/or head.

 

Yeah, pull the belts off and fire it up. It wont hurt anything.

 

Even easier, spray a little WD40 on the belts while it is running. Belt noise will go away. Watch out for moving parts.

 

Just take the belts off, WD 40 wont eliminate any internal noises in any of your pulleys.

 

Ya can't hear a rod knock at idle unless it's fixing to window the block.

 

Not true. I spun a rod bearing years ago, and it was audible whenever the engine was running. 3 days, and it locked up....

 

GM tensioner pullies are somewhat (in)famous for making noise, usually a ringing or metalic grinding noise.

i've replaced mine and the brand new GM tensioner pulley will just start making the same noise the old one did 8 months later.

pull your belts and report back, both the main belt and teh A/C belt.

 

Didn't I say "unless it's fixin to window the block".

 

That is true, but mine just locked up because the bearing seized against the crank. I think I could have just polished the crank and used stock sized bearings and it would have worked. I reused the rod and piston without any work to them at all. Just put a reman'd crank and new bearings in and drove the car another 90k miles before selling it.

The point to all that was that the noise was loud enough to plainly hear at idle....but the cause really wasn't that bad....

 

So did we ever get a diagnosis on this thing?

 

Ya got extremely lucky.

 

spun bearing, rod or crank usually means bad to no oil pressure