Alternator Woes

My 1990 Transport SE 3.1 appears to need a new/repaired alternator every 18 month.

I have owned the vehicle for over 4 years and basicly had no major problems, usual bug-bears such as heater core/front ball joints and the infamous front wheel bearings aside, the vehicle still looks brand new.

However every 18 months the alternator packs in. I have 2 repairs carried and last time fitted a new alternator ( October 2004) and here we are in Feb 2006 and the alternator has gone again. Alternator still looks brand new.

Is there a better make of alternator available ( german/japanese perhaps) cause I am getting pretty good at changing the damn thing.

Your valued advice will be appreciated. Bear in mind I am in the UK so do not have access to many USA parts stores.:banghead:

Do you know what is failing on it? If it keeps failing in the same manner, it's possible that you have a problem elsewhere that keeps causing the actual failure.

Also, are you using new alternators, or rebuilt?

Hi cdru,

1st alternator breakdown repaired by dealer under use car warranty. "2nd breakdown, alternator repaired at auto electrician , rectifer problem. 3rd breakdown new alternator fitted and this alternator is now overcharging. I can remember someone on the forum saying the position of the alternator , on top of the engine bay, can cause overheating of the alternator?

There are no other electrical problems, everything works fine and car always starts first time, everytime time. But at the moment the dashboard voltmeter shows 14/15 volts then drops to 10 volts for a while and the electrical system "slows down". When I stop and restart the volts go upto 14/15 again for a while then drop again.

I will take the vehicle back to the auto electrician and get his opinion before fitting new alternator, again.

If indeed the alternator proves failed again, I suggest you rebuild it "in house". (the book says one model CS130 is not serviceable while CS144 is...?!?) After my original was erreanously replaced under warrantee for a noise that in fact came from the A/C bearing, I was caught with a "delco" rebuilt that failed twice whitin a few years. 1st failure was an open diode: I replaced the delco pack with an aftermarket BOSCH diode pack that was light years better in quality and sturdiness. THe year after, the internal regulator failed and I replaced it, though with an exact Delco part..I could not find any other replacement. The price was $30 canadian for each occurence.
YOu have to do a lot of heavy unsoldering and soldering again - need a 250 watt soldering gun - , but the job is nevertheless straight forward.
THe delco diode pack is such a piece of scrap that I understand any kind of mishap can ruin it....so I'm glad I got it expulsed.
www.avigex.ca/xport/charging.jpg
....a little more explanations suggested by your problem. The rectifier pack diagram shows the three lower diodes to be Zeners....I was somewhat baffled by this setup initially...but then it means they can act as crude "crowbar" regulators in case of normal regulator failure....that is if woltage goes too high, these diodes in fact short themselves and drop voltage...but in doing so, they can fry themselves out of business, but then save the rest of the car electronics. THis does not explain why you can have the normal regulator go bad, but it seems to qualify the behaviour you are just reporting.