S80 - New voltage regulator kills alternator

SilverS80 · Post by **SilverS80** » 17 Oct 2016, 11:54

Pardon me if this is not the ideal place or a recent enough thread. I can tell the OP has great advice and helpful knowledge on these alternators.
My problem was low charging after about 5 minutes of running, 02 S80 T6 60,000 miles. Chose a new voltage regulator from IPD. Replaced the VR. Reconnected battery, got half a crank, then smoke rolling off the thick red wire at alternator! Pulled battery ground wire... Later I tried inspecting and testing with multimeter. Appeared to be direct short from B+/red cable connection and case on alternator. Low to zero resistance from B+ stud and casing were the same when I dismantled and reassembled the Regulator. Oh well, maybe strange but okay "short" was normal ... Nope! Half a crank (after systems charged and settled down) and smoke with glowing of the wires in my alternator! 2 burn attempts 1st cooked red wire at insulation by alternator. Second cooked alternator on the copper wiring inside!
Trying to find out why or how the alternator became shorted when regulator was replaced?
Is there likely massive damage in the alternator and should I worry about other systems?
Where can I get my alternator rebuilt, or is an OE replacement better?
Such a long ordeal and any help is greatly appreciated!

Post by **packetfire** » 23 Oct 2016, 09:23

At risk of seeming stupid, could the insulation around the red wire o-terminal have been damaged when you bolted it back on?

I ask because it looks like a clean slice on the black insulation in the photo, and I would not expect "melting" from heat of a dead short to make such a clean "cut".

Post by **oragex** » 23 Oct 2016, 10:15

I'd rather purchase a used alternator, aftermarket regulators are known to be problematic.

Post by **xiami** » 23 Oct 2016, 11:12

I have S80 T6 148,940 miles. Alternator bearing was making noise. I took it to Pequea Alternator Shop in Lancaster, PA and they replaced the bearing, regulator and cleanned/sanded rings etc for $102.24 Shop has been in business for many years and they stand behind their work. Better than buying a whole new alternator.