I have a 1992 Chevy 1500, 140,000 miles on it. I only got it two years ago, and haven’t driven it for a year (it was driven, just not by me) except the past three weeks, so I don’t have a lot of history on it.
It has always been “noisy,” but in an old truck kind of way - kind of grumbly. I honestly can’t remember if the sounds are different now than they were when I got it. I can just say they are on par with what I’d expect a 16 y/o work truck to sound like.
I’m driving along tonight, mildly hilly, mildly winding road, about 35 mph, and the noises (other than the basic engine running!) STOP. Completely. They are replaced by a sort of whining. I’m no good at describing noises, but this is not the high pitched squeal like a belt; more of a constant, lower pitched (less obnoxious…) groan (?). It’s louder when I accelerate; softer when I take my foot off the gas. Still shifts fine (it’s an automatic), as far as I can tell (didn’t exactly have a place to rev it up and try it out - nor was I inclined to).
After 2 or 3 minutes, the battery light comes on. The battery gauge is showing about a quarter “full.” I’ve honestly never paid much attention to it to know if that’s normal or not. I turned off the lights and fan, and it didn’t go down for the rest of the ride (the light stayed on).
Another 3 or 4 minutes got me home. I popped the hood up, and nothing looked obviously wrong, but it definitely smelled like something was too hot (temp gauge was normal) - not quite burning, but definitely hot rubber. The serpentine belt is intact and looks in good shape (I don’t know enough to be able to really check the tension).
So, the questions: 1) Does this sound like the alternator went? (I believe it was new when I got the truck two years ago…); and 2) am I safe driving this to the nearest mechanic? (The catch: the nearest mechanic is a half hour away, and that’s assuming I can go 55 without blowing anything up…)
Thanks…
Voltage gauges usually should read in or near the middle when the engine is running. One-quarter means it was probably running off of the battery. From your description, it sure does sound like the alternator bearing decided to kick the bucket. There is a way to be positive, though.
If you have a multimeter, check the battery voltage with the engine off; it should read 12-12.5 volts. Start the engine and check it again; it should now read 14-14.5 volts. If it does not, the alternator is not operating properly. You could also remove the serpentine belt and try turning the alternator pulley by hand. It should rotate very easily; if you encounter any resistance, the bearing is shot and the alternator needs to be replaced.
Any chance you can do this job yourself? It’s relatively straightforward, because otherwise you’re at risk of killing the battery if you drive it too far, assuming the alternator isn’t working. I’d also worry about the condition of the serpentine belt if it was being cooked on a seized (or nearly seized) pulley.
Well, I’m not the type whose afraid of mechanical things, but I wouldn’t want to try to fix it myself without someone who knew what they were doing looking over my shoulder… I also have no tools - I just moved and most of my stuff is still in storage - and the nearest place to acquire those tools (or a new alternator, come to that!) is even further than the mechanic. (I live in one of those places that isn’t QUITE the middle of nowhere, but you can see it from here!)
I’d bet, though, that one of the maintenance guys at work (thank goodness I don’t have to drive to commute!) knows how to switch the thing out (and is equipped to do so), which would mean I only have to find a way to get into town to buy the part. I think I can arrange that, so long as I’m decently sure that’s the part that’s broken! I’ll have to see tomorrow if anyone has a multimeter…
Cooking the serpentine belt is precisely what I was worried about when I smelled the “rubber too hot” smell - hopefully the 4 miles or so I drove home didn’t do any serious damage. (Of course, killing the battery halfway between here and civilization doesn’t sound like a picnic, either…) So it sounds like fixing it in situ is definitely the way to go.
Thanks for your help!
Another thing to check while working on that is the idler pulley for the belt.
Well, I did the test with the multimeter…and it’s the alternator! 12.6 volts with the engine off, and 12.2 with the engine on - plus even running the engine for about 60 seconds, the alternator got almost too hot to touch.
The belt is running smoothly (by all appearances), with everything turning (though of course that’ll be double checked when the tension on the belt is off to replace the alternator).
Thankfully, I’ve got someone who’ll put a new one on for me as soon as I can get a ride into town to buy it. Not only does that mean I don’t have to worry about getting it to a shop, but I’m betting a 6-pack is much cheaper than what a mechanic would charge me to install it… 
Thanks again!
It is worth a pizza and a 12 pack.
Try to have the job finished after 3 beers for best results.
Change those idler pulleys if the run loose like a roller skate wheel…no sense waiting & having one thing go wrong at a time… someday you may be too far from home and there are some people who want
cash rather than beer.
I was gonna say…alternator removal and installation is worth at least a 12 pack! 
On a Chevy pickup an alternator swap probably isn’t too hard. On a Nissan Sentra I’d want a bottle of 12 year old Scotch, at least on the 1986 model I had to replace one on. I got the stupid thing unhooked and it was like one of those carved wooden ball captured in a cage puzzles. Had to take all kinds of other stuff off just to get it out. Pickups are usually a piece of cake in comparison.