Ok, so my '02 has dual alt from factory and lately I have noticed a "growl" only at idle. Upon further diagnosis it is coming from the belt. So I replaced the tensioner,upper idler, and belt seeing as how they didnt look in good shape. Still there. I noticed from looking under the truck where the belt comes off the crank to the lower idler there is alot (2" or so) belt *flutter* (slap/slop) but as soon as you give it any fuel it smoothes out and the noise goes away. Let it idle and the noise comes back with the belt slap/flutter. For those with dual alternators please look at your belt from under the truck and see if yours is smooth at idle. Now I do notice it doesnt make the noise for the first few minutes of running. Next I am going to try bypassing the lower alternator and lower idler to try and pinpoint the prob. Any help would be appreciated! Thanks guys

 

This might help you out. There was a special service kit for the 2002 only :

2002/03 F-Series and Excursion Belt Squeal; 99-01 with Replaced Belts:
Some 7.3 engines may exhibit a loud squeal noise from the engine area when the engine is under load and the fan clutch is locked up, typically in hot and dusty conditions. Another complaint may be the fan clutch oscillating or not locking up. This may be due to dust accumulating on the back side of the belt and causing it to slip on the water pump pulley. This usually affects only 2002 model/year vehicles, but may occur in trucks built from 99-01 if the belt was replaced after July 01. On single rear wheel trucks, replace the serpentine belt with P/N 1C2Z-8620-NA on single-alternator engines, and 1C2Z-8620-PA on dual-alternators. Broadcast Message 3848.
A service kit has been released for 2002 trucks only. It includes a belt, tensioner and water pump pulley. Use 2C3Z-8620-AA for single alternator and 2C3Z-8620-BA for dual alternators. Broadcast Message 0718.

Hope that helps,

Austin

 

Thanks, yeah I saw that ssm, but it describes a squeel under heavy load conditions, mine is only at idle. I am going to try bypassing the lower alt/idler and see what happens first.

 

Where did u get your belt by chance? Mine did this and i replaced it with a ford motorcraft belt and it went away.

 

I actually work in a Ford parts dept. Yes it was a motorcraft belt

 

Replaced lower idler and problem still exists. bypassed lower alternator with a single alt belt and noise is gone. So I'm leaning toward a bad alt. In the back of my mind I'm also thinking bad belt but I doubt it. Should I get a new alt or just keep it bypassed. I dont pull a camper or anything just two subs and an amp. Do I really need the 2nd alt??

 

well if you decide to bypass the second alt let me know, ah heck I'll just PM ya.

 

I went through exactly the same thing as john311t, went to the correct Motorcraft belt and the problem went away.

 

You are on the right track. Had a 6.5L TD GM and in 140,000 miles I replaced the alternator 5 times and all 5 times it was the rear bearing. Fortunately, the first replacement aterantor had a lifetime warranty.

I would just bypass the second alternator and it won't hurt to leave it connected.

DSMMH

 

I have a model year 2000 F350 diesel 7.3 with the dual alternator. My lower alternator pulley bearing went bad and shredded the original drive belt. After having a Ford garage replace both parts I started experiencing the belt flutter.The flutter occurs from the crankshaft up to the first idler pulley going towards the passenger side of the truck.I took it into ford. they replaced the Alternator, the belt tensioner and idler pulley. the flutter remains. They are perplexed. they don't know what is the problem. They eventually put on a napa belt that they said fit an application for this problem. The tech told me that there was a specific application for a Motorcraft belt for this problem. But Motorcraft does not make that belt any longer. It appears I'm stuck with this obnoxious flutter unless I remove the second alternator and just go with the one. My original serpentine belt and original alternators lasted 14 years. I only experienced this problem recently after the lower alternator pulley bearing went bad as I originally stated.

 

Buy a different brand belt from somebody else and report back.
(I buy most of my parts from O'Reilly.)

 

I don't know about any belt bouncing but I had a slight squeal some time ago. Couldn't find anything wrong and replaced the belt and all was good (I also replaced the tensioner and idler pulley also). I only use Goodyear Gatorback belts now and they have done me well. Solid and quiet. For my dual alternator truck I use p/n 4081377.

 

If anyone can figure the length on the discontinued part you can always order one. I'm sure Motorcraft didn't make them anyway.

There are several manufactures that make belts for restoration engines. It's probably a stock item somewhere.

With, Length, Thickness, and # of Ribs.

 

More Information for GOODYEAR 4081377

Poly-V
8-Rib
Effective Length 137.75"
Outside Length 138.5"

Rock Auto is usually the best price (or close to it) and runs about $40.

I'm on my second one. The first one got worn down from regular usage until it was time to replace it. No cracks, tears, fraying or noise during its life.

 

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