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My 93 5.0 is currently having an alternator overcharging issue which causes the battery hiss and lose water. I took the alternator to a local rebuild shop and they replaced the rotor under warranty. The car was fine for about a day and a half and then started overcharging again. Could an issue in the wiring from the alternator to the battery cause this? This car was converted to the 3g alternator by Ford as was a highway patrol unit. Thanks for any help.
 

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What voltage is the alternator charging at when the car is idling? Sounds like you got taken for a ride. If an alternator is putting out more voltage than it should, the voltage regulator is what should have been replaced.
 

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Thanks for the reply fogged. It measured as high as 16.85 at the battery! I took it back to the shop and they agreed to look at again for free. Iam hoping this takes care of things but I was wondering about the wiring from the battery to the relay and if it would cause this issue.
 

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is the voltage regulator built into the alt in these cars?
I forget which years are not, but some are and some aren't. I think it may be the older carb'd ones that have an external regulator. I know for sure that the 3G alts are internal.

16.85 isn't going to be any wiring. Unless you have a bad ground somewhere and your meter is getting a false reading, but that's highly unlikely if it's even possible. Anytime I've ever seen this issue it's always the regulator.
 

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3g's are internally regulated and I agree it's most likely the regulator... here's a pic to show you where the regulator is. it's as simple as unbolt and bolt new on.

(ITS ON THE RIGHT SIDE IN THIS PIC)
 

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Well got the alternator back today from the shop again with a new voltage regulator and it still overcharges. It only does it if u really gun it and raise the rpms quickly. The guy that runs the shop didn't charge me and wants me to bring him the whole car as he suspects a wire problem.
 

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That's good he didn't charge you. Sounds like a decent place to do business with. Post up what they find then, because I've yet to see an overcharging issue be anything but the regulator or something internal in the alt. I'd be curious to see what the problem ends up being and if it is something that sounds like a line of BS the guy feeds you or not.
 

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Is the pulley the size of a quarter or something?

I'd ask for a NEW alternator instead of dicking around with this problem filled pos one if it were me.
 

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id have to say its the wrong size pully thats my guess if the car had under drives put on sumpoint in time and never changed the alt pully cuz im pretty sure the alt pully that comes with under drives it pretty small right
 
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