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Alternator getting hot and making noise

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Old 07-09-2015, 08:39 PM
forestgreen forestgreen is offline
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Alternator getting hot and making noise

I have a 1969 f100 ranger and the alternator gets hot fast and makes a whine noise when I step on the gas. I had tried fixing the problem by replacing the solionod, starter, battery, alternator, regulator, and the wiring harness from the alternator to the regulator. (All in that order)
Mechanic shop looked at it and told me to replace the alternator again. This will be the 2 time... But still gets hot and makes noise.
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Old 07-09-2015, 08:55 PM
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Do you have any electrical accessories that are placing a high amperage load on the alternator --such as an aftermarket stereo and amp(s)?
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Old 07-09-2015, 09:02 PM
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Originally Posted by ultraranger View Post
Do you have any electrical accessories that are placing a high amperage load on the alternator --such as an aftermarket stereo and amp(s)?
I have a cb radio but I disconnected it. Radio is disconnected as well
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Old 07-09-2015, 09:06 PM
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That pretty well rules out a high amperage load putting a drag (resistance to turning) on the armature.

Is this a bearing noise or a belt slipping on the pulley noise?
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Old 07-09-2015, 09:12 PM
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That pretty well rules out a high amperage load putting a drag (resistance to turning) on the armature.

Is this a bearing noise or a belt slipping on the pulley noise?
It's not the belt. It's sounds like a bearing. But I have bought 3 alternators in the past 2 months because some one had said the alternator is bad. When I step on the gas you can hear the alternator whining.
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Old 07-09-2015, 09:18 PM
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Welcome to FTE!

Also, first rule out a defective battery. If it does not accept a charge correctly for example, it will smoke the alternator.

Corroded connections, and grounds presents a similar problem, the regulator "sees" this as a battery needing charge. Constantly. This will ruin the battery. See the problem? It's important that charging system sees as low a resistance as possible, and a serviceable battery.

Get your DVM out and run some voltage tests at 2000 RPM with lights and heater on. At "normal" temps should see around 14.3 volts, say. "Voltage drop test" would probably tell the tale here.

First rule out the battery though.
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Old 07-09-2015, 09:21 PM
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If the V-belt is being over tightened, then it can damage the bearings.

If all the components you mentioned have been replaced and, if there's not a high electrical load on the alternator and the belt isn't slipping, I'm not sure what the reoccurring problem with it may be.
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Old 07-09-2015, 10:14 PM
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If he is running at, let's say, 2000 rpm highway speed and he doesn't hear the whine, that says something. The alternator is putting out whatever the regulator calls for. If he hits the throttle and hears the whine, how does the alternator know about the throttle position and sense that it is time to whine?
This one is puzzling.
Belt squeal on acceleration?
Squirt some WD-40 on the belt(s), see what happens, report back.
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Old 07-10-2015, 03:05 PM
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Sounds like a internal short to ground to me. Is this a cheap parts store alternator? That's prolly the problem. I've heard those cheapy rebuilts are built with low temp solder in them. Which melts. I suggest taking it back for warranty and buy the best one they got. OR better yet, do the 3G swap.
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Old 07-10-2015, 05:07 PM
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Pluck the connector out of the regulator and try again. Then, the alternator is freewheeling, no load, no diode currents. Or, take it to a competent auto electric shop and have them put an oscilloscope on the alternator output.
Check and see if the belt(s) are riding too deeply in the groove(s). Then, get suspicious of the water pump and power steering pump. Drop belts if you can.
I suspect you have a mechanical problem, not an electrical problem. You have thrown every possible electrical part at it and still the problem persists on acceleration.
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Old 07-10-2015, 07:46 PM
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I wouldn't put any WD-40 on any of the belts as it will cause it to slip. But chalk will quiet a belt down and will not be sucked into the rubber & fibers of the belt..

Have the alternator tested where you got it. And are you using the correct size belt?

What's the voltage at 2000 rpm ? when it starts to whine .

You sure it's not the ps pump or belt.

Orich
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Old 07-12-2015, 05:52 PM
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Originally Posted by JEFFFAFA View Post
Sounds like a internal short to ground to me. Is this a cheap parts store alternator? That's prolly the problem. I've heard those cheapy rebuilts are built with low temp solder in them. Which melts. I suggest taking it back for warranty and buy the best one they got. OR better yet, do the 3G swap.
I believe it's a short. I've gone threw 3 alternators there all good though. And recently since driving it the wiring harness is starting to get hot its melting the wires. Thus one is very confusing can't seem to find the problem.
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Old 07-12-2015, 05:54 PM
forestgreen forestgreen is offline
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Pluck the connector out of the regulator and try again. Then, the alternator is freewheeling, no load, no diode currents. Or, take it to a competent auto electric shop and have them put an oscilloscope on the alternator output.
Check and see if the belt(s) are riding too deeply in the groove(s). Then, get suspicious of the water pump and power steering pump. Drop belts if you can.
I suspect you have a mechanical problem, not an electrical problem. You have thrown every possible electrical part at it and still the problem persists on acceleration.
The wires are melting on the wiring harness now. I think it's a short. But can't find it
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Old 07-12-2015, 09:01 PM
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Alternator getting hot and making noise

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Originally Posted by forestgreen
The wires are melting on the wiring harness now. I think it's a short. But can't find it
Scrap it all and put in a 3G!!!
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Old 07-12-2015, 09:34 PM
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Melting harness?
Yes, you have the mother of all shorts.
Start feeling around for heat. Fuse box? Ignition switch? Headlight switch?
Start dropping circuits at the + side of the solenoid. What aftermarket stuff has been attached?
Do the lights work? Brake lights?
Get an ohmmeter. Disconnect the + side of the battery and look in. You will see zero ohms with that kind of a short. Start pulling connectors, fuses one-by-one.
We cannot tell you where your short is. They can be dogs to find.
Troubleshoot.
The forum has all the circuit diagrams that you will need.
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