alternator replacement

Jan 05, 2004 8 Replies

The bearings in the alternator on my 87' Olds Cutlass Cierra are shot. I tracked down a replacement at an auto salvage for $20.00. I don't yet have the manual for this car. Can I just swap it in, wire for wire? Are there any precautions I need to take? What about polarizing it? Can someone explain what "polarizing" does to the alternator and whether it is necessary for a used part? Thanks... Bryan


Yes, you basically just unplug the old and plug in the new - there will probably be the red wire for the main output and a smaller connector for the control and warning light wiring. Just disconnect the negative battery cable before messing with it so you don't cause a short.

No such thing as "polarizing" a vehicle alternator. An alternator in a gas-powered generator might need such a thing, but not a vehicle alternator.

I agree about replacing the bearings. What I did in a similar case was take out the bearings, record the embossed numbers on them, then take them to one of the many bearing places. The new bearings were quite cheap. I went to an electric motor place to get new brushes. At least that way you'll end up with a fully reconditioned alternator. Just make sure you remove and refit the bearings without distorting the bearing holders - gentle does it - no bashing and smashing...

Henry, Australia

Last time I replaced bearings, I went to NAPA and think they looked them up and handed them to me. I may have brought the old ones in to match, but don't think so. In any event, the local parts store may have bearings and brushes.

I replaced the alternator on my '89 Festiva with one off a wreck a few years ago. Its been fine. I did not "polarize" the alternator, whatever that means. I checked the alternator and also the charging voltage with a voltmeter according to some instructions I found in a book from the public library.

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No such thing.

Back in the days of GENERATORS with mechanical voltage regulators, the regulator sometimes had to be polarized (by applyinig a static DC voltage to its coil) in order to get it to work. They were shipped un-polarized because the same regulator might be used in both positive-ground and negative-ground cars, and had to be polarized correctly for the final application.

funny thing happened.. hee heee. on my way back from the auto parts store ( I had just ffound out I could get new bearings for $3.77 and I had found good rebuild instructions) I threw a rod and put a 1/4 inch crack in the bottom of the block... oh well...

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