Squeal on startup

[Chief Master Sergeant]

When we rebuilt the 67 we used a 3G alternator setup. From the get go we have experienced squeal on start up and from what I've read, it's to be expected with v belts. Unfortunately it has gotten worse and wont stop. The belts appear to be lined up. Is it possible it's the bearing in the alternator itself? We used to be able to rev the engine a bit and it would stop, but it's a constant now. Thoughts?

 

[EliminatorXR7]

Mine does that on start up also. I noticed that when the battery is a bit low (alt having to work more to charge it) it squeals a lot more for longer periods. I did replace the alt not too long ago, and don't think that it is the bearings. I am in need of new belts, hoping those will help.
Try charging the battery and see if that helps.

 

[cs_88]

That v belt has to be kept pretty tight with a 3G.
Installing a larger pulley can also help.

 

[Chief Master Sergeant]

That v belt has to be kept pretty tight with a 3G.
Installing a larger pulley can also help.

What would I get a larger pulley off of to increase the size?

 

[Chief Master Sergeant]

Mine does that on start up also. I noticed that when the battery is a bit low (alt having to work more to charge it) it squeals a lot more for longer periods. I did replace the alt not too long ago, and don't think that it is the bearings. I am in need of new belts, hoping those will help.
Try charging the battery and see if that helps.

Battery is pretty well charged. Need to get this fixed before the neighbors gripe too much.

 

[TN1776]

I spent the better part of the day today diagnosing a problem with my 3G alternator. I have a serpentine belt on mine and I don't get any squeal, but in my testing whenever I'd disconnect the sense lead the engine RPMs would rise at least 100rpms and you could definitely hear the revs drop when reconnecting it. They are capable of 90 amps at idle and that is a pretty large load. If your v-belt isn't tight enough I could definitely imagine it would squeal when it first starts up. Have you applied dressing to your belt at all? Sometimes that helps reduce the squeal as well.

 

[Broncobowsher]

At start up the alternator goes to full output to recover them starter draining a little off the battery. Completely natural and expected. That full load is more then a single V-belt on a small alternator can handle. The larger alternator pulley idea does a few things. One is the larger diameter gives better leverage on the alternator shaft. The other good thing is more belt is in contact with the face of the pulley. But all these benefits do come at a cost. You slow down the alternator and that reduces output, especially at idle. So using one of the oversize race pulleys may cause charging issues at idle.

The squeal is getting worse because the belt is loosening slightly due to wear from the belt doing burnouts in the pulley grooves. Cranking up the tension may help with the squeal, but that puts a huge load on the bearings and they will fail sooner.

 

[Arikilen]

I have to retighten my v-belts pretty often after the belts get worn or they will squeal. Wish I had the option of serpentine back when I did the 5.0 swap...

 

[deltarat]

I had the same problem. I went to a double pulley and 2 belts. Problem solved.

 

[broncnaz]

With V belts your going to get some squeal/slippage with a 3g. Charging ther battery doesnt help you still will use power when you crank the engine. Pretty much any alternator that puts out 100amps or more will cause V belt slippage.
Lots of people have the same issue with the V belt about all you can do is use a double groove pulley and run 2 belts. Find a larger pulley, live with it or go serp. Although you could try different belts some of the cogged style tend to work pretty well. I also seem to remember someone making a adjustable threaded tensioner that could help get the belt tighter. Which is probably part of your issue now of the constant noise the belt is probably to loose and the belt and pulley are glazed. Probably time for a new belt.

 

[Chief Master Sergeant]

Considering the fact this thing doesn't need a high output alternator (nothing besides stock on Bronco), what would I need to do to just go back to a stick alternator? I used the T3 wiring harness when we rewired it and don't recall it showing the way to wire in a voltage regulator.

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[Viperwolf1]

The wiring would be fairly easy but swapping a bigger pulley would be easier.

 

[Tedster100]

I had the same problem but couldn't find a larger pully. Ordered one from NAPA & I think it was close to a 3" but when we opened the box it was stock size. I finally made my own out of a piece of 3" round stock on the lathe.

 

[cs_88]

I believe Summit has some underdrive pulleys that should work.
I think they're a little pricey though.

 

[Viperwolf1]

BCB has them.

http://classicbroncos.com/forums/showthread.php?t=181312
http://classicbroncos.com/forums/showthread.php?t=182350

 

[jim3326]

I had the exact problem this weekend too Sarge. I tightened the snot on mine and the squeal went away, mostly, still squeals on startup. I think I will go with a larger pulley, dual belt would require changing the crank and WP pulleys as well the way mine is lined up.

I can't see having a little lower output at idle as being that big a deal, last I checked my foot is a LOT closer to the floor than that:-X

I looked on BCB and couldn't find a larger pulley for the 3g, all that was listed was the 2.5". In fact when I clicked on the 3g alt. 'Buy Now' button, it comes back with 'nothing found'.

Jim W.

 

[Casey835]

When I did my rebuild I did 3G alter, 2 groove pulley, and 2 cog style belts. It has never squealed...... Yet!

 

[Chief Master Sergeant]

I bought a new pulley from BCB. It should be here by Wednesday and hopefully help. Thanks

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[707Bronk]

I bought a new pulley from BCB. It should be here by Wednesday and hopefully help. Thanks

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Did you find one on their website? Or did you call them?

Also, I have had good luck so far using a turnbuckle w/ heim joints in place of the lower bracket. A far better way of setting and maintaining belt tension than prying on the case. But, I am worried that the bearings are going wear out and want to get the larger pulley.

 

[Chief Master Sergeant]

I called and spoke directly to Chuck. He had me measure the pulley I have and said his should do the trick.

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