Ubermensch

I've been having a bit of a problem with my charging system recently. As background, I replaced the generator 4 years ago and it's been working fine since then. I replaced the drive belt 6 months ago and it has a few thousand miles on it now. Last week on my drive to work I noticed that the voltage reading was below 12V. It was a cold morning and as I babied it to work hoping it wouldn't die, I noticed the voltage suddenly popped up to it's usual 14V. It did this for half a mile and then dropped back below 12V. I wondered if the voltage reading was accurate so I went out at lunch and confirmed the correct reading with a multimeter. The voltage reading is accurate and the generator is not charging when the car is cold. Figuring the generator had died I ordered another and plan on replacing it tomorrow.

The more I thought about it, the stranger it seemed. Normally when I've seen generators go bad they just stop working (voltage regulator dies). In this case it seems like it works sometimes and doesn't work other other times. I drove the car home from work today so I can do the replacement tomorrow. As expected the voltage reading was low (<12V) for most of the ride, but once the car warmed up it the voltage popped up to 14V. Is it possible this is a belt tension issue and the tensioner is loose in cold temperatures and tight after the engine bay warms up? Is there any spec on the belt tension?

Thanks,

Shawn

logray

I would be surprised if it is belt tension, is the tensioner roller maxed out and very close to the idler pulley next to it (lost spring/failed)? Are you certain you purchased the correct length belt?

Did you check:

the condition of the battery
see if the main power leads from the alternator to starter to jump point in engine bay is corroded
ground strap from battery to chassis is ok
ground strap from engine to chassis is ok

C4CRNA

Belts loosen up after a while and have to retightened. That may be your problem.
Also sticky brushes in the voltage regulator/alternator can exhibit this erractic behavior.
You can change out just the voltage regulator.They are available for purchase separate from the alternator.
The problem is you have to pull the alternator out to change the voltage regulator.

Ubermensch

I'll check some of these out tonight and post back up.

The generator is under warranty and I was planning on pulling it to replace my oil fill tube anyway, so I'm going to replace it. I suppose that will answer a lot of questions in itself.

ltusler

had the same issue once, turned out the lead on the back of the alternator was loose.

Mark I

Electrical issue vs. belt tension 99 to 1 odds...you'll find the solution in the regulator or a connection; pls let us know how it works out.GL!

logray

I had similar symptoms and replaced the main bat cable from the alternator/starter/jump point in engine bay. The cable was badly corroded (even though it was hard to tell just by looking at it). The problems vanished.

Ubermensch

Just to close this out, the new generator appears to have resolved the issue. I'm getting a strong 14V while charging. I did clean the connectors going to the a generator and they seem to be in good shape. I'll let you know if there are any further developments.

-Shawn

logray

Great!