Drive belt question

Besides the altenator, what other things does a drive belt drive? plus I know that at times they can make a high pitched squeel when either old or not tight enough, but has anyone every had them make a non high pitched sound when they are not operating properly?

A flapping sound if a piece is coming off a belt. They drive air conditioners,power steering pumps,sometimes water pumps ,camshafts, and air pumps and air compressors.

The serpentine belt can make other types of sound…but so can the alternators, AC compressors, power steering pumps, and (in pickup trucks primarily) water pumps thay drive. Sounds can also eminate from the tensioner assemebly or the idler pulleys used to “route” the belt.

A timing belt, also a “drive belt”, just operates the cam(s).

What sound are you hearing and why do you suspect it’s the serpentine belt?

Well my friend says the sound that I hear each morning or after long hours of the car sitting when I am in drive or reverse is making a sound from the area that the belt is located. However the noise is only there when the engine is cold like after sitting or night or after sitting for 9+ hours while I am at work. You can also only hear the noise at idle speed because as soon as you excelerate it goes away, it will return if you go back to idle. It will also go away after driving say 2-3 miles and the car/engine has warmed up, no more sound. The sound is not a loud squeel that I usually associate with belts, this is more like a deeper sound, almost like what a car sounds like with a bad muffuler. It just baffles me that it only occurs when my car is cold and in drive or reverse and at idle speed. I would think that if it was the drive belt it would make that sound no matter if I was in neutral - park also which it does not. just confusing…

I still think that you have a problem with the exhaust manifold, i.e.–either a crack in the manifold or a bad gasket at the point where the manifold attaches to the engine.

When the engine heats up, expansion of metal can cause a gap to close or to become much smaller. I had this exact situation with my POS Volvo.

And, as I pointed out earlier, a bad motor mount can exacerbate the situation.

But wouldn’t this noise be happening when in park or neurtral?

Have you tried opening the hood, revving the engine by hand, and trying to hear where the sound is originating from?

Is this a continuation of a previous post?

When in neutral or park you can rev all you want, the sound does not happen unless it is in drive or reverse and it decreases to nothing the more you excellerate.

Flex Pipe ? Motor Transmission / Mount ?

You could spend $10 to $15 or $20 (auto parts stores or Sears) and buy a mechanic’s stethoscope (the car version of what doctors use to listen to your heart and lungs).

Probe around with the long probe, but be careful and don’t stick it in moving parts or electrical connections, etcetera.

I’ve had good success with mine, but if it’s exhaust gas noise it may not find it.
For that try a length of stiff rubber hose to the ear and probe with that.


A serpentine belt, or any other “drive belt”, would be verifiable by revving the engine with the hood up. An exhaust leak would also be verifiable in the same way. I’m inclined to suspect that you’re hearing a drivetrain noise.

Let’s start with the basics. What is the year, make, model, and engine of the vehicle, and how many miles does it have on it?

Can you describe the noise better?

Or, you could spend $4.59 + tax.