Buzzing Noise Over Engine

[DjEarth]

Just started yesterday, overtop of the engine idel I can hear this buzzing noise. I know about the fuel pump buzzing and it doesn't seem to be quite the same noise. With acceleration the buzz gets higher..then when you slow down it slows down as well. Everything is running fine, no starting problems. My friend said it may be the alternator starting to go. Any ideas?

[BlazerLT]

is it a high pitched whirring noise?

[DjEarth]

Yes it is. But it isn't a extremly over powering noise.

[Rick Norwood]

PCV Valve?

[BlazerLT]

might be, easy to check and replace.

Open the hood and have a listen to pin point it.

[wolfox]

Might also be a water pump bearing going south on you. Have that looked at too if you are not mechanically inclined. If you are mechanically inclined, it can be checked by removing your serpentine belt temporarily. Grasp the fan by one of it's blades and turn it. The fan should turn the pulley behind it. If the pulley turns smooth and even then your problem is somewhere else. If it binds, feels clunky or makes a grinding noise or feels rough when you turn the fan, well, you found your culprit.

Other possibilities are bearings in the idler pulley, tensioner pulley and power steering pump. Since it is hard to describe the sound you are experiencing in text, check all of the above. Power steering pumps tend to start making noise when they are low on fluid, so check that too.

Your friend may also be right about your alternator. One way of checking is to take a 12" extension or a long screwdriver and touch it to the suspect part on a solid part of it's body. Place your thumb over the end of the screwdriver handle/extension and rest your ear on your thumb. Wherever the hum/whine gets louder, you found your part that's busted. Needless to say, be very careful when using this technique, you're putting tools and your head near moving engine parts. I used this technique to pinpoint a bad bearing that was making a whining noise in my seprentine belt tensioner. $9 later, I had a new plastic pulley in place and the problem went away.

EDIT: In my experience, sometimes a water pump bearing going out will sometimes sound like a belt squealing. A set of needle bearings on an alternator going out will sometimes make a low moan to a mid-range "Woooooo" sound like a police siren. Idler and tensioner bearings will grind and clunk. Power steering will whine and rumble when low on fluid or the pump bearings are shot, the sound getting worse/louder when the wheel is turned with the vehicle at rest. (Second thoughts always plague me!)

[czm400r]

Mine does the same ever since I had the Alternator replaced. I need to look into where the whine is coming from. Its bad enough I have a whine in the house, I don't need one in my garage.

[lou S.]

Remove the belt from your alternator and see how easy it is to spin the pulley. If it takes a lot of effort your may have found the source of your whine. When those bearings go and lock up you won't be able to turn the pulley.

[89BLAZER4ME]

I am no mechanic, but mine kinda makes the same noise, and it seems to only do it when the A/C is on...so I think it could be my compressor.

[herkyhawki]

Remove the belt completely and then start and run the engine for a short time. This will isolate all belt driven accesories so you know if your chasing an accesory or a system on the engine.

[lou S.]

Yep, a lot of the accesories that are driven by the belt contain inner bearings that can go out----finding which one it is is sometimes more difficult than actually replacing the component.

[DjEarth]

We just replaced the waterpump a few months ago so I am sure it's not that. Gonna pick up a PCV valve this afternoon and start there. Most likely it has never been replaced.

[Rick Norwood]

PCV valves are cheap, but you might want to pin point your problem before replacing parts that don't need replacing.

[DjEarth]

Checked it last night, my mechanic friend thinks it should be replaced and that it probably never has been.

[BlazerLT]

Yea, I would replace it, they should be replaced every 40k.