Blazer eats alternators like popcorn

My 94 blazer has been through FOUR alternators. Sometimes the windings burn out but this last time the bearing failed! Also I can't seem to find a new one but have to rely on rebuilds. Was that just a lousy model year for alternators or could my truck have a gremlin that affects the windings AND the bearing? Great truck otherwise. GRRRRRR....

Can't imagine what's going on with that. Try an Autozone Duralast, at least it has a lifetime warranty and not too much more money.

Get a new battery.

A defective battery that is not holding its chanrge will wear the alternator out quickly seeing it is always constantly charging it.

Charge the battery before installation, don't just install it from the store, have it completely charged up.

BTW, don't you have the warranty for these alternators?

They check the battery every time and they say it's good. Would having to charge the battery make the BEARINGS wear faster? I mean I can see the windings but not the bearings.

Warranties. Usually the things last about 2 years and by then I've moved, lost the reciept, etc. This time I got a lifetime warranty though.

Usually when the bearings go out, it is due to either a bad rebuild or too much belt pressure. Being out of alignment with the other pulleys could do it also, but usually that will cause the belt to be thrown.

How long did the alt. with the bad bearings last?

I thought that but he said the belt tension was fine in this case. The one with the failed bearing lasted 3.5 years, longer than usual. He're a summary of when I've replaced alternators:

Replaced Lasted Problem

Aug-97
Aug-99 2 years died
Aug-00 1.0 years died
Feb-01 0.5 years died
Aug-04 3.5 years bearings started whining

Does a defective battery cause alternator wear because it just makes the alternator run more often, or does it stress it some other way?

This is really helpful guys thanks...

Have you always used the same re-manufacturer of these parts.
It just sounds like a bad case of rotten luck. Most likely these units
are the same for numerous models and years of S10 trucks, so
your particular year wouldn't be the exception.

If your battery has enough power to start the truck without a jump,
it's not requiring overcharging once the vehicle is running, as the alternator supplies all power necessary to run the truck (hence the alternator sends a charge >= 14V to recharge the battery and run the engine.

With the lifetime units, at least you only have the labor/time of replacing it (no charge for your time). I would have considered a larger output unit
from an aftermarket supplier (Napa) that has brand new units, not rebuilt.

Try going with a reman ACDelco unit or from the remanufacturer : WorldWide sold by Advance Auto and Partsamerica.com One more item, please tell me that no one has ever checked the alternator for charging by removing a battery cable with the engine running. That will cause a voltage spike and cause damage to sensitive circuits including those in the ECM and the alternator. If you are buying 1 yr warrenty rebuilds, you get what you pay for. In fact, did you know that you can buy a lifetime warrenty alternator from two different parts stores, and those stores buy their remans from the same remanufacturer? The reason this is important is because companies can specify how much they want to spend on quality parts. This turns into a lower price at the counter. I had the chance to speak with representatives at A1-Cardone remanufacturer. If the part looks like it was done in a 3rd world country, it probably was.

3 and 1/2 years is pretty good service.

I would be tempted to find a alternator rebuilding shop locally and have them replace the bearings in your alternator rather than replace it. Might cost a little more, but should be worth it.

Whatever might have been wrong and killing the old alternators sounds like it got fixed and you now just have to fix a mechanical defect.

I thought that but he said the belt tension was fine in this case. The one with the failed bearing lasted 3.5 years, longer than usual. He're a summary of when I've replaced alternators:

Replaced Lasted Problem

Aug-97
Aug-99 2 years died
Aug-00 1.0 years died
Feb-01 0.5 years died
Aug-04 3.5 years bearings started whining

Does a defective battery cause alternator wear because it just makes the alternator run more often, or does it stress it some other way?

This is really helpful guys thanks...

Bearings are usually a sign of piss poor workmanship. Are these AC Delco Remans or some shop?

Also, make sure you belt is the appropriate length for your specific truck. Go and get it referenced.

I hope you claimed warranty on these quick wearing alternators.

I did get an alternator with a lifetime warranty so now if it goes again I'll only be out labor. Talked to the shop owner all about tension, the battery, etc and he said all that was fine, thinks I'm just unlucky. Thanks for the help.

Di it yourself.

Alternators take about 15 minutes to install.

The 91-94 alternator bearings are tension senstive. Make sure belt tensioner moves freely trough full range of its travel. Will eat bearing up if not right.

The sign of the bearing going is the high pitch humming coming from your engine.

Another thing that will burn up alternators are loose battery cables and the side posts like to loosen themselves

Guys you all have some good advice. The first question I would ask is do you have a aftermarket radio system in it?? Is it a kick arse system(pulling a lot of amps)?? Any other aftermarket stuff that eats a lot of amps??
Sec. its not the voltage out put but the high amp load that eats alternators. Do you have the correct amp size alt for that truck??
A weak battery will cause a alt to put out low volts and high amps untill the bat is charged.
Next please make sure that ALL THE BRACKETS AND BARS on installed. If any are missing that will cause the alt to shift and put way to much load on the bearings.
Just a few things to think about