This may some how relate to my last post. On start up (hot or cold)the belt(s) let out a horrendous squealing noise. Isuzu95 posted about something similar, but I'm not ready to start a big project. Daily driver, so I need to keep my work on it to from a few hours to a day at most. Here are the exact symptoms. On start up the squeal sounds to be coming from either the upper or lower pulley on the engine, but it is intermittent, it just goes away, then will come back. I'm leaning toward the alternator because it happens under electrical loads (no A/C Trooper) but the noise is not coming from the alternator area. Using the factory gauge as a reference, the electrical output drops below 12v, probably close to 10v, and slowly climbs back up to just over 12v. At this point the noise stops. But turn on the heater fan to high, or the lights and the voltage drops below 12v again and the squealing returns. Tonight I was driving and everything was good, hit the brakes (brake lights) and the squeal came back. Drove about a half a mile like that with the squeal until the headlights and dash lights became noticeably dimmer. Pulled over, shut off the lights and after about 2 minutes the volt gauge crept back up and it stopped. Isuzu95's post was about a similar noise under loads (but associated with his a/c and power windows) and it was the harmonic dampener. I've read about doing a "full field" test but I'm not comfortable enough yet with this vehicle to try it (also I need it to get to work, not to mention parts). In the morning I was going to try and loosen and re-tighten the the alternator and make sure the belt is aligned and the tension is correct. Then test it on the drive to work. Any help or other ideas? Specs are '92 Trooper S, 210.000 miles, 3.2L, SOHC, 5sp, 4X4, auto locking hubs, no a/c, no power nothin' except brakes and steering. P.S. If anyone knows of an Isuzu specialist in SoCal, Orange County area, let me know.

I had to say it, but it sounds like a classic case of an alternator that is not putting out what it should be.

I don't have a lot of experience with the 3.2, but my memory is that the alternator is located low on the engine (bad design) and can be a b#$*h to get off.

Thanks, for the reply Jim. Yes, lower right, but I have plenty of ground clearance to get at it from the underside, and without a/c, it's the only belt on the pulley. Unfortunately the one closest to the engine. Tomorrow (Monday) I was thinking of just going to the autozone near me and have them test the system, but after 2 visits in 3 days, I'm loosing confidence. The first was to get a shop manual (they have a big selection in the store) but they didn't have one. I asked about ordering one and the kid asked if I checked the web site. The second was to ask the difference between "works on your vehicle" and "fits your vehicle" on the web site when looking at parts. Got a blank stare on that one. Think I'm going to loosen the alt belt, and start it up, listen for the noise. Then tighten it back up and start it again and go from there. Seems to be the common protocol for back yard testing with minimal tools.

Well, did some work on the Trooper today. Went in from the underside. Took off the skid plate and went into the loosening procedure for the alternator. Turns out the last person who last put the belts on (they are relatively new) didn't tension them correctly, or didn't tighten the tension bolts properly. They were already loose. So I tightened everything up and began the tightening steps from the beginning. Got the belt tight and re-tightened the bolts. Fired it up and no problem. Let it idle for a bit, cycled electrical devices on and off, no load, heavy load, everything was fine. Shut it down, let it cool off, turned on the headlights and fired it up. No problem (little slower to turn over with the lights on though). In dash volt gauge shows 12+ volts and only a slight drop when putting a load on, but quickly goes back to "normal". Still going to get the batt and alt checked again by a different shop.

Great news!!