My early 91 TA eats alternators just for fun. I'm now on the fifth one for the car. It gobbled one at about 30,000 miles, another at about 60,000, another at about 65,000, another at about 73,000, and another one tonight at about 78,000.

Each time it's replaced they fully check out the system. Also, I double check the shop, checking output, max voltage, for too much heat anywhere, any amp draw with the switch off, battery condition, etc., as well as watch them work on it to see if anything seem goofy. All seems just fine until either the voltmeter drops and I notice it early enough to limp home, or until it dies on the freeway at 1:00 in the morning like tonight.

Is there ANYTHING that can cause this repeatedly, yet check out fine when the alternator is replaced? Wiring intermittent short or open (which wire?), poor ground causing spikes, or ?!?

The only clue I have is that occasionally the voltmeter will drop down to about battery voltage when driving, and after a short time it comes back up.

I either have to fix it once and for all sometime soon, or park it - and I REALLY like driving it.

 

Just a guess - I posted a circuit in your other thread - do you have the resistance wire leading to the ign switch, or has it been replaced by a regular wire for some reason? Not 100% sure but I believe this can cause a failure over time.

What dies - the whole alt (ie windings, diodes, brushes etc) or just the regulator?

 

Tighten up the female side of the metal electrical connector inside the plug that goes into the alt.
Sometimes they get loose. What brand alt are u using? offbrand or Delco?

 

MULTIPLE ANSWERS

Assuming a resistance wire should be there (I have a volt meter, not an idiot light), I don't think the resistance wire has been replaced, but not sure. I've owned the car since new (except for about 1500 miles driven by a Pontiac zone office), and don't remember anything about it. It was a very early 91, so if that feature was unique to that year, or that year and following, this one might not have gotten it.

Time before last, it was the diodes or regulator, not sure which. This time (back again and running ok) they said it was a cracked housing (didn't show on the outside!?!). All the earlier times, I didn't find out exactly what it was. One time I was going to the desert, had to get towed to a small town, R&Rd the alternator myself, and was on my way in a couple hours.

As for the connectors in the plug - I understand, and will check that out. I can shake it around, and pull on it a bit, with no problems. What's the best way to tighten it - stick a probe down alongside it?

These last two are rebuilt units, HD types.

 

Yes on the plug just unhook it and look in there and you will see the flex part that keeps the metal female connector on the male pin. The plastic plug will wiggle around... but keep from doing it as much as you can.
I'm not saying this is the prob but its a place to start..

I have always had very good luck with GM delco. Not so much with the cheap replacement stuff..

 

I went through about 5 or 6 or more and finally got a CS144 and re-wired it and it stopped. I put my battery in the trunk (optima) and an electrical block (junction) on the passenger fender and ran good audio wire everywhere. #4 from the alt to the block, 2 ought from the junction to the battery. The good audio wire has thousands of strands and since electricity works off of surface area the more strands and the bigger the wire the better. I had custom 130s made, napa and autozone alts and it made no difference. After about 6 or 8 months; stranded. Now I can jump the car from the front or back. There is a bracket kit you can get to install the CS144. I bought an extra for my other car and they are easy to install but you have to get the right CS144 so do your homework if you go that route. It is worth it. I will eventually put this on my other three F cars as well. My volt needle never ran so high and strong. You can tell it when you start the car.

 

Agreed, I too re-did all my power wiring with large audio power cable and juction blocks, and saw the same difference.

 

I have no doubt that the CS alternator is better than what I used, but I think the rewiring done with success by others points to a problem with wiring. While the audio wire is excellent, the normal wire should be "good enough", if it's right. The plug is one part to check. Anything else?

 

check the bulk head connector. that brown wire supplies 12v to the alternator and fan system. i found this to be my problem after i converted to the cs144 alternator and still burned up 2 more in less then 8 months. wiggle the connector next to the booster while its running and keep an eye on the voltage to that brown wire. should be ignition voltage all the time when running.