Alternator Running Hot - Diesel Truck Forum -
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post #1 of 3 (permalink) Old 06-09-2012, 04:09 AM Thread Starter
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Alternator Running Hot

Swapped an alternator for a 98.5-02 Dodge 2500 Cummins into a 95 Dodge 2500 Cummins. The only difference i can see on the backside of the alternator is that instead of the 2 wires that plug into the 98.5-02 the 94-98 has one that bolts on. Ive got it hooked up by splicing the wires from a Weatherpack and wrapping them around the terminals from the original harness on the truck. Its charging to ~14V just fine, however the alternator gets hot to the point that its safer to touch the exhaust manifold after a few minutes. Its a brand new 200A unit from Geno's Garage. My old unit had something rattling around inside it and it had ~200k miles on it so i wasnt thinking it was the PCM/ECM. What could be causing this excessive heat?

My Rig: Midnight Blue '95 Ram 2500 12v, Long Bed Ext Cab, 5 Speed Manual 4x4. BHAF Straight Piped. Pump Untouched
198k miles

The Wifes Rig: Montego Blue '97 Ram 2500 12v, Long Bed Ext Cab, 47RE Auto. 4" Downpipe, AFC Screw tweaked a bit, Plate Full Forward.
177k miles
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post #2 of 3 (permalink) Old 06-15-2012, 06:52 PM
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Over Charging. incorrect wire size. Faulty alternator from the beginning.

Why go with one from a 24v and get one for a 12v? The best advice I can give you is to get an alternator for a 12 valave from someone like NAPA and try that, I would guess your problem will go away.

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post #3 of 3 (permalink) Old 09-02-2012, 12:30 AM
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THe 2 control wires on my Bosch alt 2001 are just in and out for the slip rings( rotor load) The max draw is 5 amp. This is typical of all alternators, no matter how they are controlled. You could use an old style Mopar external regulator with this alternator. Don't see where a 12 valve alt would be diffrent. Should charge between 13.6 and 14.4 volts. Amperage output that can cause mucho heat should cut back quickly after start unless you have a bad battery.
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