Please help / Alternator issue

1990 Cherokee Laredo
4.0
A/C

Hey, I'm replacing my alternator today and wanted to hear any ideas on what might have happened to my last one so I don't ruin this one.

The previous alternator started whining and when I pulled off the road I noticed smoke/heat coming out of it. When I started it back up it made some light grinding noises and after about 15seconds started to shoot sparks out of the front. I'd assume that whatever rotates in there is making contact with parts it shouldn't.

Any ideas what could cause this? I recently replaced my power steering pump, maybe I tightened the belt too much and strained the alternator? Also, does anyone know what voltage I need, the auto parts store has multiple?

Have you played in any mud lately?

Worn out alternator blowing up. That's what it sounds like to me.

Avoid mud...that's about all you can really do to prevent this. I've killed 4-5 alternators in the last two years, a couple were freak accidents like the pulley shooting off or the internals breaking apart. Make sure you get an alternator from a local shop with a lifetime warranty.

No mud lately, but plenty over the summer.... maybe it's been coming for a while?

Yes. the location of the alternators on XJ's in america is terrible, If you do a search there are some "How-to's" on relocating it up to the AC location..

I've never had one blow up, but heavy water spray and mud will make them go nuts! my battery gauge used to shoot to 19+ volts for a good 5 minutes every time i splashed threw a puddle.. I put a sheild around it (kinda) and it helped tremendously..

Yea. Mud will do that too it. Especially the mud we see in washington. Wears down the bearings until they sieze or the brushes make contact inside the alternator. I have one with like a two year or lifetime warranty, cant remember. But Ill just clean mine up and take it into them. They've replaced three for me now.

Ok, cool. I just wanted to make sure I wasn't putting too much strain on it or anything like that. Thanks.

Honestly I've had better luck having the alternators re-built rather than purchasing a re-manned one. As you probably know the quality on the re-manned accessories can be terrible. There's a great auto electrical re-builder near you in puyallup, I've purchased their services myself.

Alternator & Starter Exchange 10814 Valley Avenue East, Puyallup, WA 98372 (253) 845-9390

I would agree with Sideshow, a local re-builder will almost always give you a better product than a parts store reman--and if you talk real nice sometimes they will boost the output for you.

I've had similar events a couple of times, and usually it's rust buildup. sometimes you can clean it up, and if the bearing is all right it will go fine. But once it's done it once, it tends to do it again if it sits for a long period of time.

dielectric grease all over it before you reinstall it.