big stinky

When I first bought my truck it used to charge at idle at 14 volts. Now it doesnt charge at all idling. At a stoplight with headlights, blower motor, signal lights, brake lights etc, its sitting at 10v. This happened gradually over 2 years. It does get to about 14 volts at @ 1100-1200 rpms (ear guestimated)

Are these symptoms of a worn out alternator, or a bad voltage reg?

Any input would be greatly appreciated.

JD730

Those sound like symptoms of a worn out alternator. My brother's 96 just did the same thing.

Firstgenfanatic

Yes, I'm wondering the same thing. My lights get dim when I come to a abrupt stop or when I stop and back up. The volt meter shows 14 or so volts, then drops to 9 or 10 volts. The idle changes and the lights dim. If I give the truck throttle, the voltmeter jumps back up to 14 volts and the lights brighten. Thinking the alternator is getting weak?

jimbo486

rebuild the alternator. should normally see 13.6-14v with the engine running.

Firstgenfanatic

I have taken alternators apart before, should be a simple changeout of brushes/bearings?

wannadiesel

Probably just brushes. If it doesn't feel bad when you spin it the bearings are good to go.

TractorMike

Thats definitely an alternator.. I had one go out on my ford truck, Did't really show any signs except the voltage would drop some, Which I thought was normal till I was driving it one day and my battery light came on and then next thing I knew my alternator exploaded.. Now I know what to look for in the future

Trebor

[1] Is your idle speed set correctly? [2]Belt & tensioner in good shape? [1]+[2]=Your situation. When I was repairing alternators you would be surprised on how many alternators I received that were in perfect working condition. I had a lot of repeat customers that came back because of honesty.

big stinky

My idle speed sounds about the same as all of the rest of the stock trucks I've heard.

And answers to your questions, yes and yes. Both are as they should be. Thanks for the suggestion tho.

97catintenn

Why wouldn't it be the external regulator?

rebal

try and use compressed air and blow out the alt. real good. I have done this several times with mixed results. some times it starts working better other times nodda