High pitch whine won't go away

Maintenance/Repairs
1

I have 2002 Chevy suburban. Recently, a high pitch whine has developed. When accelerating the whine intensifies. I replaced the alternator … No change! What could it be? Speedometer cable?

2

If the noise is there with the engine running and the vehicle not moving you might consider a worn belt tensioner bearing.

It’s not a speedometer cable as it does not have one. Cables have pretty much gone the way of the dinosaurs.

3

I agree with @ok4450. Also make sure the idler pulley isn’t the source of the noise. Is the belt flapping around a lot at idle? What is the condition of the belt? How many miles?

4

I would also check the transmission fluid level. A low level can sometimes make the torque converter whine. Check the power steering fluid as well.

5

Thanks for all your input. Here is a bit more informaiton:

  1. The noise is worse when standing outside the car. Keep in mind . . . it is not deafening . . . it is just very irritating
  2. The noise definitely increases when accelerating
  3. If I turn the radio to AUX (where i have an Ipod plug in) and do not plug in the ipod . . . the noise increases significantly through the radio
  4. However, the noise is there even with the radio off . . .
6

@ErikKrieger how handy are you?

If you’re pretty handy and have a few tools, remove the serpentine belt and run the engine without it. For a minute only!
If the noise is gone, it’s definitely caused by one of the belt driven accessories, the idler or the tensioner.

7

If the noise is coming through the radio, I would bet on a bad diode in the alternator. This will cause an alternator to whine audibly. Get a short length of hose (or a mechanics’s sethascope) and put one end of the hose against the alternator and the other end against your ear. If the noise is louder in your ear when you put the end of the hose on the alternator, you’ve isolate the problem.

8

" . . . I would bet on a bad diode in the alternator. “
” I replaced the alternator … No change! "
CSA

9

The replacement alternator could be defective. If the sound comes through the radio, it is some sort of electrical interference.