Alternator super loud

[John_parkeriv]

Hey y'all,
Doing some work on my rig and heard the alternator make a TERRIBLE screeching noise when it started. One of the case bolts is missing to clear the mount for the head, that's all I can think of; but it's sandwich flat against the engine.

Any ideas on good solutions?
Thanks,
Parker

 

[DirtDonk]

Sounds like belt squeal.
Are you running a V belt or a ribbed belt?
When it does it just during start up, that usually means the belt is slipping under the heavier load of the initial charge. Doesn’t look like a stock alternator, but no matter what it does need at least two bolts fastening it down.
It’s probably not as much an alignment issue, as it is a tension issue.

Also, belts and the grooves they ride in get a glaze on them over time. Especially when slippage is an issue.
That’ll make it worse.

How long has it been doing it?
And how long is the alternator been like that?

 

[John_parkeriv]

Sounds like belt squeal.
Are you running a V belt or a ribbed belt?
When it does it just during start up, that usually means the belt is slipping under the heavier load of the initial charge. Doesn’t look like a stock alternator, but no matter what it does need at least two bolts fastening it down.
It’s probably not as much an alignment issue, as it is a tension issue.

Also, belts and the grooves they ride in get a glaze on them over time. Especially when slippage is an issue.
That’ll make it worse.

How long has it been doing it?
And how long is the alternator been like that?

Factory type V-belts. 3G alternator with oe pulley from old alt. Does have 2 bolts holding the case, and the upper / lower bolts.

Normally only makes noise when starting, but have had it stick around

Alternators relatively new, a year max. Been doing it most of the time it's been on, but it's gotten worse over time

 

[Bajabrewer]

Pretty common with the 3G V-belt setup - I just went all summer(May-October) without any squeal - I posted this a while ago on another alternator squeal thread
Hope this helps


I just went thru this with my 69-351w The belts needed alignment so I used some shims like these
https://www.ebay.com/itm/3943896744...d=link&campid=5335857059&toolid=20001&mkevt=1
I also installed a larger pulley on the alternator 3.25" instead of the 2.6" that came on it - larger diameter gives more surface area for the belt to grab.
https://www.ebay.com/itm/3044206208...d=link&campid=5335857059&toolid=20001&mkevt=1
Not sure which made more of a difference but with the belt super tight I only had it squeal once & that was when I got some water on it from washing the engine compartment. I do want to go with the Explorer serp set up but I'll wait & do that next winter when it will be off the road anyway. I also read somewhere that the Gatorback belts(pricey) made a difference but I didn't need to try them.

 

[Broncobowsher]

As mentioned, pretty common with a single V-belt on a 3G. Did you get the 130A or the 90A version? Most people just take the high output option. This puts even more load on that single belt.

If you look around for a slightly larger diameter pulley, that can help. Does 2 things. The larger radius takes the leverage out of it, think using a longer handle wrench to get the torque when trying to remove a bolt. The other is the larger radius has more belt contact area. But this does come with downfalls. The output of the alternator drops as it is slowed. A larger pulley slows the alternator. The good thing is the 3G still makes good output at pretty low speeds. So long as you don't go too big you should still have decent charging at idle. Now finding that larger pulley, that can be a challenge. At times it doesn't take much, 2.1 to 2.3" or 2.3 to 2.5". Without going to the race 5" pulley. My last project I did a 3G to keep up with the EFI and A/C at night in the rain. Just a 90A and everything was fine, stock pulley worked great, never a squeal. Enough to keep up with modern loads.

 

[knack]

Have you thought about going to a double groove pulley? I did that a few years ago and it's been working great. No more squeal, for the first time ever.

Pulley came from Summit, I think. Use the original alternator belt in one groove. A longer second belt will drive the power steering-water pump-crankshaft and alternator.

 

[DirtDonk]

Definitely all viable solutions.
Larger diameter pulley.
Larger diameter with deeper groove/sheave.
Dual sheave pulley.
Serpentine setup.
Just pick the one that works best in your mind initially. If you ultimately don't like it, the others are still available.
The first three are also fairly inexpensive and easy to install, so you're not out that much time or money if you decide to go another route.

I did the dual groove pulleys on my '71 originally. Even easier than knack's because at the time I did not have power steering.
Explorer serpentine on the '68 eliminates any need for mods.

Paul

 

[Madgyver]

shoot wd40 on alt pulley, if sound goes away, it's the belt.

 

[John_parkeriv]

Definitely all viable solutions.
Larger diameter pulley.
Larger diameter with deeper groove/sheave.
Dual sheave pulley.
Serpentine setup.
Just pick the one that works best in your mind initially. If you ultimately don't like it, the others are still available.
The first three are also fairly inexpensive and easy to install, so you're not out that much time or money if you decide to go another route.

I did the dual groove pulleys on my '71 originally. Even easier than knack's because at the time I did not have power steering.
Explorer serpentine on the '68 eliminates any need for mods.

Paul

Mine actually already has a 2 grooves alt pulley. May have to give that a shot

 

[nvrstuk]

Pretty common with the 3G V-belt setup - I just went all summer(May-October) without any squeal - I posted this a while ago on another alternator squeal thread
Hope this helps


I just went thru this with my 69-351w The belts needed alignment so I used some shims like these
https://www.ebay.com/itm/3943896744...d=link&campid=5335857059&toolid=20001&mkevt=1
I also installed a larger pulley on the alternator 3.25" instead of the 2.6" that came on it - larger diameter gives more surface area for the belt to grab.
https://www.ebay.com/itm/3044206208...d=link&campid=5335857059&toolid=20001&mkevt=1
Not sure which made more of a difference but with the belt super tight I only had it squeal once & that was when I got some water on it from washing the engine compartment. I do want to go with the Explorer serp set up but I'll wait & do that next winter when it will be off the road anyway. I also read somewhere that the Gatorback belts(pricey) made a difference but I didn't need to try them.

Is your crank pulley aftermarket alum?

 

[Bajabrewer]

Is your crank pulley aftermarket alum?

Nope - stock ford steel

 

[nvrstuk]

Reason I ask is that there was a run of alum pulley's quite a while back that would literally SCREAM when they got antifreeze mix on them. I mean people wouldn't believe ya loud. Like at idle you could literally here it over 800ft away- not kidding.

Anyway, Continental makes a non-squeal belt "Gatorback" I believe it is/was called. Cuts it 100%. Antifreeze does make certain compounds of belt and pulley combo's squeal.

Obviously high alt/amperage load on startup makes a huge load and even double pulleys with decent V belts still squeal.