Hi-
I have a 95 Montero w/ 3.0 engine. I have been through at least 7 alternators in the last 3 years. They are not bearing or mechanical failures. Somtimes a diode would fail and dash lights etc would flicker. In most cases, the simply stop putting out power until the battery goes dead. I have tried rebuilds from a reputable alternator overhaul place, plus 3-4 remanufactured units.

Any ideas about what could be killing the alternators?

Thanks

Dirty battery connections.....
Loose Ground....
Bad Batteies?...
Too much Load on the charging system? What sort of electrical "stuffs" have you added?

There is a trm called field dump. I fthe alternator is putting out signifigant amount of current and the laod gets disconected the voltage goes up rapidly.

Eventually the protection diodes conduct and shut this power to ground. However they ahve a limited life and can only do this so many times.

Once the protection diodes fail the voltage surges will hurt the main diodes.

A voltage dump is caused by a loose connection from the alt to the battery or a bad gound.

thats just on scenerio...

Or you cuold be getting crap rebuilds.

Kevin

Thanks for the responses so far.

The electrical system is stock. I have not added any of the usual toys like lights, winch, etc.

I have replaced the battery cables and the battery. I also tested the battery recently.

I have not check the grounds lately. Maybe I have corrosion under the ground connections. I will try that. If anyone has other ideas, keep them coming.

Thanks

My Gen I alternator was on the bottom and kept getting filled with mud. I had no failures other than that.
I used NAPA rebuilds.
Bob Shaw.

Hey dog2

Are you still having problem with your Atl. I'm asking beacuse mind go out 8 - 12 months each time.

I had problems with my alternator when I first purchased my montero. Then found out it was from a different model mitsubishi. They mounted it out wierd, I went through belts like crazy.

I feel your pain..

Upto #7 (I think) and my record for replacing one is about 40mins. Checked all the usual suspects, even bought a new battery. In the end I chalked 6/7 of the failures to poor quality rebuilds. They all seemed to die due to the diode pack quiting - typically the voltmeter would peak to 18V just before everything went dim. For reference, a 95 3.0 will travel >30m on a good battery,lights on and and no charging.....

Number 7 was a used OEM which lasted about 5k. Current unit was also used (rebuilt,not OEM)and (touch wood) is nearing 10k. Just in case, #9 sits in my garage.

There is a link to rebuilding them on the 3000GT site ( I think)if you're keen.

Paul
'95 3.0 LS

Just use a Diamante ( or other 120A alternator ) & put your own front case on. Bolt it up * you have a much healthier regulator & diode pack. Mine reads 14.1VDC with all possible accessories on, including 900W of stereo amplifiers.

Ed

What makes the Diamante Alt special I wonder?

During my repeated sampling of the Advance Auto Parts rebiulds, I noticed the range of bench output currents varied drastically. I had one unit that supposedly pumped out 150A,another that barely made 100A. Didn't seem to correlate with how long they lasted though. The variability was one of the reasons I went elsewhere - figured a stock unit should be 90A and getting well above that was a recipe for trouble.

Aside from poor quality rebuilds, my only other theory is that in the 3.0 motor, the Alt (and diode pack)is quite close to the header pipes. I wondered if a generic rebuilt Mits Elec unit (they are standard on a lot of import brands)just wasn't upto running near a heat source?

Paul