Whining sound when jeep is started and when accelerating

jeep
grand-cherokee

#1

My Cherokee recently started making a whining sound when I start it up and when I accelerate (I’m not able to post the video I have of it). It mostly happens when it’s cold outside. Once the engine warms up it stops. Everything handles as normal, haven’t noticed any difference besides the sound. Recently got a new battery and starter. I replaced the serpentine belt and tension pulley about 2 years ago. The belt and all the pulleys look good to me.

The sound is clearly coming from the alternator. I’ve had alternators go out before, but never heard a sound like this. Is it going bad? I have the V6 so with all the extra space in the engine compartment it would be a very easy fix. But if I don’t have to drop the money I dont’ want too.

Ideas? Do I need a new alternator?


#2

A couple of idea you could try before replacing the alternator. Use a length of old garden hose as a stethoscope to isolate where the noise is coming from. Using a wooden dowel or metal rod can work too to transmit sounds from an exact spot. & check the belt tension of course, and that the belt remains in good shape, none of the pulley’s are wobbling, etc. YOu could also loosen the belt so it wasn’t spinning the pulleys temporarily, to see what that does. Careful to only do this for a brief time, particularly if the belt also runs the engine’s water pump.

Alternators can indeed make a whining noise like that. Usually it is the alternator’s bearing that is going south. Try this. Trun on the headlights to bright, does that make the whining noise louder or change in pitch? That would be consistent with a defunct alternator bearing.

If it is the alternator bearing, you can either do what most folks do, replace the alternator. Or you can do what us frugal folk do, take it to an auto electric shop and have them just replace the bearing. I prefer the later for one b/c it costs less, and two, b/c you retain the oem alternator the car came with. But it can take la bit onger to get the job done. Best of luck.


#3

11 year old part and your sure it is making noise. Just replace it. Don’t know where you are located but I try to avoid getting stranded in freezing weather.


#4

I would recommend confirming the noise coming from the alternator as George mentioned but it does sound line stator whine.