I have a '99 Chevy Lumina 3100 V6 with 54k miles. There is a high-pitch buzzy whine that changes pitch with engine RPM/transmission speed. I removed the serpentine belt and drove it briefly - the noise is still there without the belt. So it's not the power steering pump, alternator, H20 pump or belt tensioner. Transmission has had regular service (fluid is full and clean) and shifts smoothly in all gears. The noise is only evident while moving (forward or reverse) above 5 mph. There is a slight raspy "scraping" noise in park or neutral, which becomes almost undetectable when shifting to drive or reverse with the brake still applied.
If the car has to be moving it is most commonly a noisy wheel bearing. That can happen on any brand of car but with GM's bolt-on type of bearing it can be impossible to tell which one it is that's making the noise. The only sure way that works for me is to run it in gear on a hoist, then listen next to each one with a stethoscope. The noisy one will be obvious.
November, 16, 2012 AT 4:52 PM
Thanks for the response.
Ordinarily, that would make sense, but wouldn't a wheel bearing make the noise all the time while the car is in motion? In my experience with bad wheel bearings, bearing whine and pitch is consistent with vehicle speed (engine/trans RPM). This noise can only be heard while accelerating - when I let off the throttle, it all but disappears - and it changes pitch, dependent on engine RPM/transmission range (when the trans shifts to a higher gear, the pitch of the whine is lower - when the engine RPMs go higher, during acceleration, the pitch of the whine gets higher). Pretty much the same effect you would hear from non-resistor spark plugs over your radio speakers, only this isn't an electrical issue. This is a "whizzing" type of noise, very odd.
November, 16, 2012 AT 4:57 PM
** Correction ** What I meant to say in the previous post is: "In my experience with bad wheel bearings, bearing whine and pitch is consistent with vehicle speed, not engine/trans RPM". Sorry about that.
November, 16, 2012 AT 9:20 PM
Everything I can think of I can discount based on some of your observations. I was considering a rubbing timing belt or noisy idler pulley but your engine uses a chain. Perhaps the chain is stretched and rubbing on the cover. I've had a few axle seals that caused a high-pitched squeal and was wondering if a front crankshaft seal could do that too. That would occur any time the engine is running. You wouldn't have to be moving.
There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.
November, 18, 2012 AT 4:52 PM
Thanks again, I'll check around and see if I can find that tool.
November, 19, 2012 AT 12:55 AM
The guys on the tool trucks sell them for $200.00. There's a newer model in which four of the microphones are wireless. I've seen the older version on amazon. Com for less than $70.00, but since you may never use it again, try to find one to borrow at an auto parts store.