Heres the deal. I've got a '79 4x4 pickup.
A couple weeks ago the alternator started whining and squealing. So last Friday I put a reman alternator in, 55 amp, same plug and markings as the one I replaced. I started the truck and backed it up a bit, I got out to gather up the tools and left the truck idling. Not long after I heard a 'pop' almost sounded like a fuse popping but much louder. When I got back in the truck the whining noise was back!
Anyway it seemed to be charging and working OK so I took it out wheeling for the evening yesterday.
As soon as I was headed for home the charge light came on. I parked it at a nearby friends house and found a ride home.
Today I got a new regulator for it, installed it this evening. The charge light went out on the dash but according to my meter it is not charging and eventually the voltage dropped to about 11.5 measured on the battery.
I tossed the old regulator back on, the charge light comes on and off every few seconds, when the charge light is off the engine slows down at idle. When the light is on the engine revs a bit higher.

Did my old regulator cause the death of my new alternator? Should I get another new alternator and keep the new regulator installed?
Any ideas?

Thanks in advance!

 

any ideas?

 

how good is your battery?

 

the battery has been great. new this summer, never run down. never had a problem.

 

When you replace the alternator it is good to replace the regulator at the same time. I replaced just my alternator and my regulator fried it, the new alternator had a lifetime warranty so the auto parts store gave me a new one. With both new parts it worked fine.

 

i went and got a new alternator today, i wont have time to put it in till friday. so i borrowed a spare optima red top, threw it in and drove it home, the battery was just under 12 volts when i got home. it was a 25 mile drive or so with headlights on. I'll keep the new regulator and put the new alternator in and see what happens.

i just discovered tonight that the turn signals dont work now either. sometimes i hate electrical problems but thats what i get for buying a 28 year old truck.

 

Definately do the regulator.

On my old Chevy when I replaced the alternator (not the voltage regulator, just the alt) I had some weird electrical problems for a short while after.

Whiney sound is probably from a loose belt.

 

HAd the same issues with my 82 pickup up. Kept on switching out the aftermarket alternator and regulator and they kept on not charging the battery.Ended up getting an alternator and regulator from the dealer, haven't had an issue since.

 

i think i discovered the issue last night. the ignition switched input on the regulator is at approx 10.5 volts. it looks like it uses that as a 'sense' or reference to charge from. it thinks the system is running low voltage so its full fielding the alternator overcharging the battery. the problem seems to be in the actual ignition switch. key on engine not running im getting 12.6 in the ignition switch and only 10.5-11 volts at the ignition switched wire (black-yellow) the actual switch is worn or dirty or both. i ran a jumper from a good source to the ignition terminal on the regulator and it was then charging at 14.3 at idle. seemed perfect. i'll do more conclusive testing tonight and verify whats up.