Belt pulley noise on 97 C230?
 

Car has developed a slight whirring noise when cold in morning, followed by a rhythmic chirp from up front that sounds like some kind of bearing noise. I don't know if the 2 are related but they started at the same time. The whirring is fainter but similar to the noise I've heard in a lot of 90s Chev/Pontiac V6 cars on acceleration - know what I'm talking about?

I had the chirp. I changed the belt and it is gone.

Mike

What does the whirring noise sound like? Is it a faint sound that is proportional to RPM when the car is cold, or is the sound of the AIR pump that you are referring to.

As stated above, a new belt will should take care of the chirp. If your old belt has not been replaced in a while and is developing multiple small cracks accross the ribs, then it is time for a change. That can be changed easily and belt should be around $30, which can be ordered from fastlane at the top of the page.

Thanks Mike and Ali. The belts looks good.............strange.

It's a chirp, but the whirring noise, separate, is proportional to RPM.

To test my belt I had a plant spray bottle adjusted for a fine stream and I sprayed the moving belt a couple of times to see if that had any effect. It did so that is why I figured it was the belt. As for the whirring noise, use a "sounding stick" or mechanics stethoscope to track it down. Be careful near the moving parts!! Don't touch anything moving of course, just put the stick near each possible noise source. Likely candidates are the tensioner, alternator and water pump. Or AC compressor or PS pump maybe.

Mike

Mike, what is a sounding stick? I understand what it does, but I have no clue where I'd look for one unless this is the "official" name. Where could i get one, or a cheap mech. stethoscope?

Basically you can use any rigid stick or tool that is long enough to keep you out of harms way. I have used yardsticks, long screwdrivers etc. Right now I have a stick 1/2" x 1/2" by around 28" long. Or a dowell rod would work. You pinch one end with your fingertips and put your pinched fingertips in your ear and the other end pushing against the alternator body or whatever. Works great. I finally bought an actual mechanics stethoscope but I find it too loud so I just use the stick method. The steth might be better for tight areas or quieter sounds like listening to injectors I suppose. Only thing to rememer is that even good bearings will make some whirrring noise. But when you find a bad one it will be REALLY loud and raspy.

Mike