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Old Sep 30, 2008 | 09:20 AM
  #1  
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cje07
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From: Rochester
Alternator Question

Hey guys...first some info... 1986 Full Size Bronco, 302 EFI. Converted to a 3G (130amp) alternator a few years ago. Just last week the 3G went down hill...

I picked up a Junkyard 3G and replaced it last night. Power was good, 14.8 volts at the battery, had power to run all of my accessories, kept the battery charged etc.

My quesiton is this, whenever I get my electric fan kicking in "something starts squeeling like a banshee" and my voltage goes down to 12v according to my cab gauge. I can't tell if its the 3G bearings or the electric fan bearings or maybe the belts are too tight. If I give it a little gas...the squeel goes away for a little bit.

Any ideas?
 
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Old Sep 30, 2008 | 10:35 AM
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From: Easton,Ks
An alternator has the power of a motor running backwards. The more of a load you put on it the more it wants to turn backwards.
In short it is the belts slipping for the alternator, if the belts are to tight you can loose bearings. You may have to add a belt to the pulley system or put the old fan back on.
 
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Old Sep 30, 2008 | 10:40 AM
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cje07
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From: Rochester
Originally Posted by subford
An alternator has the power of a motor running backwards. The more of a load you put on it the more it wants to turn backwards.
In short it is the belts slipping for the alternator, if the belts are to tight you can loose bearings. You may have to add a belt to the pulley system or put the old fan back on.
Yep I think I figured out the issue. Went outside to push on the belts and looks like I need to tighten. Everytime an increase load (actuation of the E-Fan) is placed on the alt is when the squeel starts...brief periods of time. I'll tighten that baby up and see if the issue goes away!

Thanks Subford for confirming! Appreciate the speedy answer!
 
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Old Oct 1, 2008 | 03:21 PM
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From: Rochester
Verified....yep belt was loose!

Made it home last night and tightened the smog pump belt and alt belt and all is quiet on the home front! Love it when a plan comes together!
 
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