Weird 4AC Alternator Problem

[Herus]

So, continuing with the bad luck I have with cars, with the hilux blown its motor twice, and the cressida with a bhg, I thought I was going to be fine when I started driving the car that the missus had been for about 12 months...

Ive been in it 3 weeks, and I noticed the battery light come on, after the car had been sitting for about 5 days. Checked the battery, and 12v there while the car was running.
Occasionally the light goes out, and it goes back to putting 14v into the battery, but always flicks back on again, generally for longer periods then its off for.

Now its been doing this for about a week, and I know its only a matter of time until the battery goes flat, and I'm left stranded on the side of the road somewhere.

Generally, you would say that the alternator has died, but there seems to be something that doesnt add up.

When the light is out, the alternator provides full voltage to the battery, no hassles. When its on, 12v is at the battery, and there doesnt seem to be that much power draw.

When the light is off, turning on everything electrical in the car does nothing to make it come back on again, it just flicks back on when it feels like it.

The light usually goes off when the thermo fan comes on, almost making it seem like it has a bad earth?

I have had a quick look at under the bonnetand everything seems to be connected fine, but its generally dark when I get home, and who can be bothered first thing in the morning?

I just want to know if there is anything I should look at, before I head down to Upullit, and spend my time removing an alternator from a 4ac down there, then having to install when I get home.

Thanks guys.

Herus

[Chrisso]

I don't have an answer for you, but if you suspect it might be a bad earth or other electrical, then why not test it before pulling, paying for, and fitting a new alternator? If it is wiring, then you'll be exactly where you are now except that you've wasted time and money fitting another alt.

There are only 4 wires running of an alternator so make sure the connections and continuity are good. If you've got an external regulator you should probably check this too (though I'm not too sure exactly how - wiser heads will know). From the regulator 2 wires will run to the fuse box, 1 to charge fuse, one to engine fuse, and the other to join the B+ wires going to the AM1 (maybe AM2) fuse on the Battery positive.

Search for a post on 4ac to 4age alternator by Rex Kelway, and have a look at the EWDs, either on mr2oc or as posted up by Parrot

Chris.

[oldcorollas]

it could be that the brushes are juuuust on their way out, sometimes touching, sometimes not.
change brushes yourself (even if you take the pulled apart bits to auto elec to solder for you) should be cheap.

alternatively, alt is loose on brackets?

[Herus]

The other thing, after the light has been off for a period of time, just before it comes back on again, there starts to get static through the radio, like there is electrical interference.

Herus