Charging system trouble?

[propony]

I am having a gremlin in my charging system. I was waiting to pick up my kid at school, car idleing, a/c on, listening to the radio, when the battery light came on. I looked to the factory gauge, that usually reads above 13, was reading below 13. I shut all accecessories off, and brought up the rpms.
I brought the car home, checked all connections, all clean, and reassembled everything.
Now when I start the car, the volt gauge is reading below 13 and the light is on, but it goes out in less than two minutes, and the gauge goes back to the above 13 that I usually see. When the light goes out, and the gauge comes up, it is like someone flipped a switch.
I have a battery maintainer on the car at all times. I used the pigtail from the maintainer to check the voltage with a digital meter, and get 12.71 and dropping when the light is on, and 13.85 when the light goes out.
Should I trust that all will be fine? Anyone ever see this situation before? What should I check next?
Thanks in advance,
Curt

[Chris4099]

Sounds like your alternator is going out. Normally I would say a bad ground connection, but those symptoms are usually more consistent. The fact you are seeing an actual voltage change with the light tells me it's most likely the alternator. Do you know which type you have? If it's the Ducy, then you should replace it regardless.

[stevedmc]

I would upgrade the ground connection with Hervey's $30 kit regardless but it does sound like you could have a bad alternator or the belt could be loose.

Autozone can test your Alternator for free if you bring it in. It only takes 15 minutes to remove and if you bring it in (vs having them test it on your car) you won't have to listen to all the BTTF comments. Just tell them it is a Saturn alternator or better yet, say it sort of for a kit car.

You can cross reference it with a 91 Saturn SL if you want to use an Autozone part. You will need to swap the pulley (I think Autozone can do) and you will need some washers wrapped in electrical tape for a spacer.

[propony]

I have the Motorola alternator. Are these serviceable? The only corrosion was on the small spade connector, what part is that, or what is its purpose? The service manual shows the part, but not listed in exploded view key.
Do alternators go bad slowly, I thought they were either good or bad, not a slow death?
Thanks,
Curt

[stevedmc]

It can be rebuilt by a qualified shop. It all comes down to what your needs are. If you are looking to stay stock/concourse then you should get it rebuilt.

For me it just boils down to cost and reliability. An Autozone unit is only $105 + $25 core. You can either return your old alternator to Autozone or see if one of the vendors will buy it from you for the core charge + shipping. The drawback to the Autozone unit is you will have to swap pulleys and use a spacer. The benefit is cost and a lifetime warranty.

If you get one from Hervey it costs a little more but it will require zero modification. I think he even includes a belt, voltometer, and pigtail connector. You will probably need to purchase a GM pigtail adapter if you get the Saturn Alternator.

[David T]

Check all of the electrical connections and make sure the belt is not slipping or bottoming in the vee grooves. If everything checks out then the alternator is warning you that it is dying and should be rebuilt or replaced. At the same time have the battery load-tested and if it is over 5 years old just replace it.
David Teitelbaum

[content22207]

DeLoreans are alternator killers because of the mounting location: high on the engine, right above an exhaust manifold, and turned around backwards. Heat is an alternator's #1 enemy.

Do yourself a favor and buy an alternator with a lifetime warranty, preferably from a nationwide retailer so it can be replaced easily if it fails while on a trip.

Bill Robertson
#5939

[propony]

I have read about GM alternators being retrofit on our cars, Saturn has come up, but is this easy to wire? Do any diagams exist?
I know buying from a vendor is prefered, but if I need a replacement, around the corner works best, in the interest in time.
Thanks guys,
Curt

[DMCMW Dave]

DeLoreans are alternator killers because of the mounting location: high on the engine, right above an exhaust manifold, and turned around backwards.


And in the rain right behind the rear tire.

[sdg3205]

I had this happen to me as well. 140A Motorola from DMC.

Turns out "the shaft was bent." Got a rebuild for $80 with a year warranty.

[dmc6960]

DeLoreans are alternator killers

Well whoever rebuilt my original Motorola alternator before I got my car did a mighty fine job on it then. Almost 100,000 miles (on the alternator since rebuilt) and it still puts out good power. Its been through heat, cold, rain, and even occasionally snow.

I just don't think they build them like they used to. Ducy excluded.

[DCUK Martin]

turned around backwards.


As I've pointed out to you before, the fan is an extractor - it sucks air through the alternator body. By your thinking this would be a better way of mounting it.

FWIW the Renault units have a waterproof plastic duct with hose attachment which can be plumbed from a "clean" source of cool air.