1986 Grand Marquis owners needed... need help

An alternator, or a voltage regulator, can be bad but still work...until it doesn't. My theory on Roger's charging system failure is that the regulator shorted, full-fielding the alternator on a very hot day, and the alternator burned up.

 

Also, if a diode fails in the trio package you can have enough regulator control and remaining diodes to keep a mostly steady charging voltage output but it will still remain on and shorted when the car is off, leading to a drain. A "bad" alternator can still have a good output!

 

Yeah so it seems. I unplugged the voltage regulator last night and the battery was perfectly fine this morning. Ordered a new regualtor. I guess there aint too much to chose from here? I mean, a stock alternator in a completely stock car, will work with either one of the two regulators the Rockauto.com carries, right? https://www.rockauto.com/en/catalog...+v8,1197064,electrical,voltage+regulator,4884

 

Yes, the design is standardized. Use a paper clip to hold the brushes away from the commutator till you have the regulator installed.

 

ohh okay, good tip. I was ready to just pull the old regulator right out
I assume there's a tiny hole that the papir clip i.e. can go into, to hold the brushes?

 

Yes. I'll see if I can scare up a diagram. And it's only for the brushes going in, not the ones coming out.

 

So you can pull the regulator just like that, but you’ll never get the new regulator in there, if you don’t put in a paper clip or drill bit or whatever, to hold the brushes in place, right?

 

Make sure you separate the case on the end where the brushes are located. When you separate the case, the brushes will pop out and the springs will go flying. They need to be pinned in place when you reassemble the case, otherwise you mess them up. Be careful when reinstalling the case as the brushes have to slide over the commutator without damaging them. You may even want to install a new diode trio while it's apart. It's all a very easy process.

 

Pulled the old regulator and brush holder, simple stuff.
Replaced the regulator, put the springs and brushes back in place and stuck a piece of welding wire in to keep the brushes in place.
No biggie.
Power drain gone

 

Woo hoo! I love it when a fix is righteous!