Alternator Running Hot

CanfieldOO7 · 06-09-2012, 04:09 AM

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?

**neeltburn** · 06-15-2012, 06:52 PM

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.

oldbeek · 09-02-2012, 12:30 AM

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.

06-09-2012, 04:09 AM	#1
CanfieldOO7 Dirtbag Join Date: Oct 2007 Posts: 41 Points: 346 Thanks: 1 Thanked 0 Times in 0 Posts	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

06-15-2012, 06:52 PM	#2
neeltburn ADMIN/MAFIA Join Date: Dec 2008 Location: Evansville, IN Posts: 4,591 Points: 29,518 Thanks: 293 Thanked 650 Times in 566 Posts	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. __________________ When written in Chinese, the word "crisis" is composed of two characters. One represents danger and the other represents opportunity.- John F. Kennedy 2012 Ram 2500 Crew Cab Big Horn 6.7L 68RFE 4wd Yeah its stock. Edge Insight CTS / Line-X / Access Bed Cover B&W Turnover Ball THE RULES Support the Vendors who Support TDG 9-11-2001 NEVER FORGET

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09-02-2012, 12:30 AM	#3
oldbeek Junior Member Join Date: May 2012 Location: Lancaster ca Posts: 26 Points: 4,555 Thanks: 2 Thanked 0 Times in 0 Posts	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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