On my 88 GTA, I've noticed something weird lately. It's like the alternator is kicking off an on. When I'm watching the charge guage, it will drop to around 11 volts, then back up to around 14. It goes back and forth constantly. If it's at night, I can see my headlights getting dimmer, then brighter. Sometimes, it quits after I've been driving for a while and stays at 14 volts. But when it's acting up, it will go back and forth from around 11 volts to 14 volts maybe 20 times a minute. It's annoying. Could my alternator be going out on me? Thanks for any info! Matt

 

TankerChief,

My first WAG would be brushes or worn slip rings (most likely the brushes). They can be purchased in a kit for about four dollars. If you haven't had any other charging system problems, I'd strongly suggest replacing the brushes, testing the rectifiers, and checking the bearings (regrease the rear bearing) instead of trading for a remanufactured alternator. Rotor winding failures are nearly as rare as dinosaurs, and stator winding failures are uncommon as well. There isn't much to check on the regulator except connections. Just clean everything, test diodes and winding continuity, and relube/reassemble. You should be good for another 80,000 miles. If the front bearign is rough, noisy, or loose, you'll have to remove teh sheave and cooling fan, a snap ring, and replace the bearing - MRC 6203PP / Fafnir 203PP, IIRC. About six bucks for a new bearing, and it should be available at the same place that offers brushes.

 

You could also check to make sure that the belt is not loose.

 

DOH! Yeah, I missed the obvious. I guess I assumed that would have already been done. The '88 should have a poly-V belt and automatic tensioner, but they do fail at times...

 

I'm having similar problems... but looking to get a replacement alternator for an eventual addition of a strong audio system. Are there good aftermarket replacements, or should I just go with a reman?