i have a 2001 gmc yukon xl 8.1 and my alternator is making a wining noise i...

[cazh_it]

...got it checked they say its fine? its running at 14v

[Molson02536]

Originally Posted by cazh_it

...got it checked they say its fine? its running at 14v

The electronic components are good, but the hard parts may be worn (bearings), and the alternator will need to be replaced soon. One easy way to tell is to remove the serpentine belt and spin the alternator pulley by had and feel to see if there is any play or resistance to the spin of the pulley. The other thing also would be a bad stator and the rectifier is working harder to produce the 13to 14.5 volts that you are getting.

A "growling" or "whining" noise is just before an alternator gives out. The alternator is driven by a (accessory belt) or a serpentine belt in conjunction with the crankshaft pulley. The alternator pulley typically spins about two or three times faster than the crankshaft pulley to produce the power necessary at lower engine speeds, such as at idle. The alternator pulley spins on a shaft, which in turn is supported by either bearings or bushings. If the pulley is not in correct alignment with the belt, if it's canted on the shaft or if the bearings and bushing are worn out, the growling or whining noise will let you know there's a problem.

The scent of burning rubber or hot wires will often accompany alternator failure. A pulley that isn't in alignment or not turning freely will cause more friction on the belt, which creates heat and then the smell of burning rubber. The hot wire scent can be caused by an overheated alternator, one pushing too much power through the rotor and stator.

Good Luck and keep us posted and start looking around for replacing your alternator soon. Shop around and look for a place the rebuild alternators in your area and see if there are any upgrades that can be done to your alternator that will not cost you to much extra money like having a double rectifier installed like the ones used on emergency vehicles. Just call around and you should fine one, I have a double rectifier alternator on my Jimmy with a higher grade bearings installed which cost about the same as a alternator from the dealer but 200% better.