bad alternator?

[porsche newbie]

Has anyone ever had an alternator go bad in 2 weeks? I have a 85.5 na and my alternator went bad a couple of weeks ago. After having it checked out it was a bad alternator and I replaced it with a rebuilt Bosch. Everything was fine for a couple of weeks and suddenly there is no charge going to the battery. Battery reads consistently at 11.5-12 and when I start the car, there is no change at all. I have just never seen an alternator go bad this fast but I guess it is possible. Just wondering if this has ever happened to anyone else or what else I could check to narrow my search for the cause.

[John_AZ]

I have not but when I worked in an auto parts store it did happen but it was easier to just give the customer another rebuilt than explain that it may be caused by his wiring.

I read your recent post. You mentioned when you turn the ignition switch the fans may come on.
fans running on their own

Clarks mentions a bad/cracked ignition switch may cause these symptoms.
http://www.clarks-garage.com/pdf-manual/elect-17.pdf
and
Ignition Switch Replacement

Does the dash battery/charge light go on when you turn the key?--not starting the car.
If the dash charging light does not go on there could be a short in the tiny blue wire from the alternator to the dash charge bulb.
This circuit must be complete to make the alternator work and charge the battery.

GL
John

[VINMAN]

Alot of times it is just the replaceable brush/regulator unit on the alternator. Not the whole alt itself.

[Rasta Monsta]

I have had that experience with a rebuilt Bosch unit.

[mytrplseven]

I don't trust rebuilt alternators. You don't know where the parts come from, or how throrough they worked it over. I've read many blogs on several of my family cars about rebuit Alternators only lasting a short time. This is the one part I would only replace with new. And...if you buy one on ebay or some other outlet, make sure it's not made in China. All due respect to an emerging economy, their alternators are junk.

[porsche newbie]

I finally got around to getting the time to pull the alternator again and it was indeed a bad alternator. I have never seen an alternator go bad in 2 weeks but then again,I have seen things on these cars that I have never seen on any other cars before either. My next question is "IF" this alternator goes bad again, what type of alternator do other people use that might have a little more reliability. I realize that it was a rebuilt alternator, but Bosch has usually been pretty reliable but I definitely have reservations about putting another one in if that happens again.At least it was covered under warranty so that helped but I still don't want to replace another one so soon.

[VOTS89]

I don't trust the testing process.

About two years ago the charging light comes on in my F150, I go to AutoZone and have it tested. Test says the battery is bad but alternator is good. I buy a new battery and get back on the road. About a half hour later, the charging light comes back on. I go back to the same AutoZone for a retest, this time the alternator tests bad.

I leave, go to a different AutoZOne for another test, this time it says the new battery is bad but alternator is good. I leave, go to Checkers for their test. They tell me the battery is good but the alternator is bad. I realize it's possible the battery and alternator were on the way out at the same time but I would expect consistent testing results.

I end up buying a new alternator from Checkers and that fixed my charging problem, came with a lifetime warranty also. I bought the new one because it wasn't much more than a reman unit.

Bruce

[Danwvw]

I had my Alternator quit charging on my 1988 Porsche 924s and found out it was just the Dash lamp that is the Alternator light. Turns out it is part of the circuit to excite the alternator.