Alternator belts squeeling

[max1008]

I talked to my mechanic and he said that the pulley on my alt (ebay purchase) is the wrong size so the belt doesnt sit in the groove right. He said to tighten the **** out of it. So I did, no more noise!

 

[PAm1009]

I just did this monday fixed it right away.. It seems mine is always the driver side alt belt that gets stretched the most. Nothing like waking up my nieghbors at 630 in the AM to that sound

 

[85CUCVtom]

Also make sure your alternators are properly aligned. If not, they will accelerate the wear on the belt by side loading them. You may be missing a spacer on the mount or a bent bracket or something similar. Pic below shows a spacer missing. This caused the alternator to mis-align and create a belt squeal, even with a new belt installed.
The belts must also be tight. A new belt may be tight at first, but it will stretch after a short time and will need to be re-tightened. Usually the second tightening will be enough.

This is what was causing squealing on my M1009. It didn't have the spacer so I had to make one out of washers until I can find one or make a better one.

The GM part number for the spacer is 14067725 and is discontinued.

I found the part number in the TM's. Then Google searched it and cross referenced it with the NSN. That gave me a page with the specs for the spacer.

The overall length calls for 45.3-45.mm, the OD is 19mm, the ID is 10.7-11mm. That makes a wall thickness of about 8mm.

It should be pretty easy to make one, especially if you have some machinist friends .

Hope this helps somebody out there.

 

[M923driver]

Same problem here, Mine started squeeling constantly. I messed with tension with no avail. I pulled the plug on the alt and it instantly stopped squeeling. When i plug back in it starts up again. Im guessing that something inside is squeeling when the alt is energized. I guess its time for a rebuild?

You probably just have slippage issues. The alt has a load on it, charging the system. Especially right after a cold start. The batts have taken a big draw from the glow plugs and then another from the starter, so the alt is trying to bring them up into the "green". When you unplug it, the load is gone and thus the slippage and the noise. The previous posts which suggested roughing up the pulleys or adding comet, ect to the belts should help, along with being sure they're aligned and tight as you can get them. Belts also tend to squeal more when cold, as in at first start up. Gatorbacks seem to grip a lot better too.

 

[max1008]

M923- I tightened the **** out of them and it solved the problem. Must have been slipping!