Hot and Squealing Alternator Belt

[ledzilla]

Looks like the third pulley is the same as the first two, just with one groove instead of two. All three are for a 3/8" belt. This whole thing is quite frustrating. Trying to find a used pulley is tougher than I anticipated, seems like I'd have to obtain an entire alternator just for a pulley or maybe find a way to have one fabricated. If I had the funds on hand I would just an entire billet pulley kit from CVF Racing, since the other pulleys are a bit on the crusty side and could use replacing. I'm actually surprised that merchants like LMC Truck and Jeff's Bronco Graveyard don't appear to sell pulleys.

So it has to be the wrong alternator pulley right?

A belt can sit flush with the top of the pulley but never out at all. At that point you are in theory losing contact area on the sides of the belt and wearing them out faster. Which you already knew.

Can't remember all the details but years ago I had a similar issue on a '73 bronco. I ended up cutting a new pulley for the alternator on a lathe. There was no internet, no u=pull salvage yards I could walk around and compare too or take measurements from.

Here is just another crazy thought. I had a 6.2 diesel suburban and the alt belt was totally unreliable. PS belt would keep the water pump going, but you would loose charging and often wouldn't know until it was too late. I remember one trip, we drove halfway cross the country, been driving for 24 hours, never shut the truck off once.
Driving through the parking lot at our destination off it came. No rhyme or reason.

So I bought a set of pulleys for a 6.2 diesel used. Cut them and welded it to my original pulleys adding a second alternator belt. Never had another belt problem. That was the front belt on that engine. Not sure if you are set up the same.

I don't think I need to go that route. I think for the one instance where it popped off instead of getting shredded and snapping I forgot to just run the engine for a bit to break in the belt and then tighten it again.

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Right now I have a 1/2" belt installed that's far too short. The alternator doesn't even need the mounting/adjustment bolts properly tightened because it's currently at it's physical limit for adjustment, and it's on really tight. In fact, I had to crank the engine really quick in order to finish installing it. I keep forgetting to check the wear on it, but so far it's holding together. Once I get back out there and check on the belt again, if perhaps it doesn't appear to be damaged I might just try the 1/2" belt again and then be more on the ball about the belt break-in.

 

[ledzilla]

I was able to take a look at the current belt, and it's sitting almost the same in both pulleys with a 1/2" belt. It doesn't appear to have any unusual wear that I could see, either. I'm guessing maybe the problem I had with the last 1/2" belt was that I forgot to re-tension the belt after initial break-in. Right now the current belt can't be re-tensioned as it's far too short. It required a quick crank of the engine to get it installed, it's so tight. I'll probably have to cut it off to remove it as it would likely be a bad idea to try to remove it using the same "installation" method I used, would likely be dangerous as I'd probably need to use a screwdriver or something to sufficiently deflect the belt to get it to pop off.

So, I guess I'll order another 1/2" belt of sufficient length (ordered two before of different lengths, didn't think the currently installed one would be that short), and then swap them out, but this time run the engine for a bit to break in the belt and then re-tension it. I think that might solve the whole problem.

 

[grumpy old man]

Just found your post and had a similar problem with a motorhome years ago. Anytime I got on the road I carried two extra belts and the tools to change them. A friend suggested getting an aftermarket pulley that was bigger than the original to make it easier for the belt to turn it. Do not remember what size pulley was but it was about half again as big as the original.

For what it is worth that pulley and belt were still on the motorhome when I sold it.

 

[ledzilla]

OK, so the new 1/2" belt is holding into place better. Doing the job right seems to have made a difference. I installed it, ran the engine for a while, then tightened the belt again. Although, in the process, I think I found what may be the culprit behind the last 1/2" belt popping off. Looks like the harmonic balencer is in bad shape, wobbling something fierce at idle. Smooths out once the RPMs kick up a bit. Guess I'll need to be buying one of those, soon.