Alternator issue.

[n1265]

Bought a new 140 amp Alternator for my truck and it is making a whining noise under a load. I contacted the seller and was told my belt was to short.

Does this make any sense to you guys ?

[oldmopar]

a overly tight belt could stress the bearings but I do not think it would whine unless the bearings are dry. Usually when one of mine whines its time for a new one. I have a 100amp on my truck and it does not whine at least not that I can hear. Does it still whine after you adjust the belt, there should be a little deflection I think about 1/2" but I just do it by feel

[n1265]

I converted my truck to a GM si10 140 amp one wire alternator. When I disconnect the power wire, the whine goes away. hook it back up and the whine comes back. The Alt is suppose to be BRAND NEW, not a reman.

I have tried loosing and tighting the belts but get the same results.

I am running a 6.5 in crank shaft pulley and the Amp has a 2.2 in. pulley witch should put my pulley ratio at 2.95 ( witch I think is in limits )

I just never heard of the lenght of a belt effecting an Alternator like this before.

Am I missing something ? or is the seller of the Alternator just giving a BS story so I don't return the Alt?

[oldmopar]

I would drive it over to the parts store and let them hear the sound that should solve the problem.

[n1265]

well, I took the alternator apart to see if I could find anything wrong with it and everything in it is brand new.

I have a lot on my plate right now and simply do not have the time to mess with it, and therefore will have to live with it .


Many Thanks to all who responded to this thread.

[n1265]

For those of you following this thread :

well as time went on, the noise got worse. So I decided to get a new belt. The new belt I got had ribs on the ID VS the OD and the belt would squeel like **** for the longest time before it got warmed up.

So I took the pulley off and noticed that the V machined in the pulley looked like one side had a greater angle than the other, it also looked like the V of the pulley was chrome plated.

So I sand blasted the V in the pulley and bought ANOTHER new belt that had the ribs on the OD ( like the original ) and guess what ? The original noise and aquired squeeling are gone.

Was it the belt ? I don't know.

Was it the smooth surface in the pulley ? I don't know.

Is it the uneven machined V in the pulley and I am just getting lucky for now ? I don't know.

But I do know it is belt / pulley related. I just hope it don't come back.

[Don Williams]

Thanks for the follow up. Always nice to hear "the rest of the story."