MechE00

Hey guys.. I've searched around, and while I didn't see anyone with my particular symptoms, I'm planning on checking my grounds this weekend based on what I've read.

Anyway, here's what's going on.. two stages..

Stage 1, this past fall
Driving the car on a long road trip from Fl. to Pa., I noticed that the voltage would do an occasional dip from the standard 13-14ish V region down to 12ish. Each individual dip would last from a fraction of a second to several seconds, and they would come in bursts, and the fan for the AC would slow at the same time. Most of the time, though, the car was running at the 13-14ish V region, and the car would go for a few hours at times between bursts.

Replaced the alternator shortly after I finished the road trip.. it was old, and I thought it was the voltage regulator going bad. The problem seemed to go away for a few days after the alternator was replaced, but I wasn't running the AC during that time since it was cooler.. so I'd be less likely to notice. I observed the problem again the next week or so..

Stage 2, the past few days
Start the car, voltage is reading steady 11ish Volts... after about 6 minutes of driving, the voltage starts occcasionally jumping up to 12 V, then after a few more minutes, it spent most of it's time in the 12 V range, but still dipping down. The lights brighten when the voltage reading jumps up. (I say 11 Volts, but actually each successive day sees that low number drop lower as the charge that is being depleted is apparently not quite being made back up).

Anyone seen this problem before? Anyone have suggestions other than check grounds/alternator connections?

Thanks for any help you can give.

edit: fans don't dim, they slow down.. duh..

Icemark

If you really have replaced the engine grounds, and checked belts (that have the correct tightness, not too tight!!... not too loose!!) then I would say a bad alt... probably at least one diode in the internal rectifier.

When you hooked up the new alt, did you disconnect the battery??? if so did you make sure that you hooked the ground cable up to the battery last??? (you should have). Incorrectly installing the alt could lead to that problem (again after checking the belts for deflection, and have replaced the stock worn out grounds).

Anytime the gauge is showing less than 12.6 volts the car is running only on the battery and the alt is not charging.

MechE00

Thanks for your help!

In the end it was the pulley. It seemed plenty tight before, but I got a little longer cheater bar and made it a bit tighter, and the problem went away.

I wouldn't have expected a loose pulley to cause the voltage level to jump around like that.. but maybe that was just the voltage regulator acting since not enough power was being transmitted to the alternator.