Alternator whine under load
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Tuned
Joined: Apr 2008
Posts: 331
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Alternator whine under load
I have already done a 3G alternator upgrade on my 82 F100 4.9 w/AC. Did it several months ago and havent had any issues. However, when I have the heater blower on high with both wipers and lights on, then something squeals more than the fat guy in Deliverance. I know I read about this somewhere before I did the upgrade but now I cant find it. Anyways, can someone point me in the right direction on this? Oh, I should mention it does NOT do it at idle, only when on the gas - even a little.
Lead Driver
Joined: Nov 2013
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Are you talking about an electrical whine, such as coming through the radio while you're trying to sing along to The Carpenters? (We don't judge...)
Or do you mean a mechanical squeal, such as belt slippage?
Or do you mean a mechanical squeal, such as belt slippage?
Lead Driver
Joined: Nov 2013
Posts: 7,174
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You have discovered this new alternator requires more oomph to drive it compared to the stock unit. A single V belt can only transmit so much power. Whenever the alternator requires more power than the V belt can deliver, you will get slippage. There are a few minor things you can do to change the equation, short of converting to a double belt drive. Can't guarantee this will eliminate the squealing completely, but it should decrease it.
1) Get a new drive belt, if you haven't already done so. If the existing one has been squealing on a regular basis, it will be glazed over.
2) Make sure the belt tension is correct.
3) Try some belt dressing. I've had good luck with this stuff to stop minor squealing. Here's one brand, Permatex #80073. This or an equivalent should be available at any auto parts store:
https://www.permatex.com/products/lu...g-conditioner/
4) Have your battery load tested to make sure it is in good condition and fully charged. If it won't hold a full charge, your poor alternator will be working extra hard to keep the voltage up. It would be like to trying to blow up a balloon with a hole in it. Reduce the electrical load and this will make it easier on the drive belt.
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Tuned
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Lead Driver
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If at all possible, get new belts from the same batch. You might find some sort of batch number or date code. Otherwise, if one belt was just a smidge longer than the other, the tighter one will end up trying to carry most of the load.
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Tuned
Joined: May 2013
Posts: 396
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From: Ottawa, Canada
What else is driven by the two alternator belts? On my 3g I have the water pump and alternator on dual belts. With the belts pretty tight it will squeal on startup and for the first minute or two if the battery is near dead but works fine 99% of the time. I have a switch in the dash so I can turn on the alternator after startup.
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Tuned
Joined: Apr 2008
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I know its been a while. Since the weather is cooperating and I'm stuck at home, I put on new belts and no more pig squealing lol. Also finally got around to upgrading the headlight wiring harness with one from LMC.
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