94 G20 strange noise from belt drive
October 19th, 2021, 5:04 AM
#1
94 G20 strange noise from belt drive
Getting a noise that sounds like it's coming from the belt drive somewhere. It's intermittent and not a squealing sound like a failing idler pulley but more of a low grinding noise.
What's odd is that it seems to come at low RPM and idle, but then for instance if I am stopped in gear and start to drive even slowly, it goes away.
I would use some kind of hearing aid, stethoscope or what have you to try to isolate it but it's hard to do that around the fan and so forth. So I am unsure if it's the A/C clutch, the alternator or what. I thought initially it was the A/C clutch but what I read online those should make more noise when you run the engine RPMs up, while this seems to do the opposite.
I will probably change the idlers as they're cheap insurance, I may have a spare alternator or I may still be able to pick up a used one (never hurts to have a spare of that) but before I throw anything else at it I thought I'd see if anyone else had ideas.
What's odd is that it seems to come at low RPM and idle, but then for instance if I am stopped in gear and start to drive even slowly, it goes away.
I would use some kind of hearing aid, stethoscope or what have you to try to isolate it but it's hard to do that around the fan and so forth. So I am unsure if it's the A/C clutch, the alternator or what. I thought initially it was the A/C clutch but what I read online those should make more noise when you run the engine RPMs up, while this seems to do the opposite.
I will probably change the idlers as they're cheap insurance, I may have a spare alternator or I may still be able to pick up a used one (never hurts to have a spare of that) but before I throw anything else at it I thought I'd see if anyone else had ideas.
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DavidDeBord (April 14th, 2022)
October 26th, 2021, 8:04 AM
#5
Well at least that shouldn't be too bad to change. I've done those before. I had one on the 91 I had lock right up solid and eat the belt, not sure what happened to it but it smelled like it was just about on fire afterwards.
If anyone else has to do one, I forget which year but they'll show it doesn't interchange all the way across 88-95 - but it will. The case is just clocked 1/3rd turn off, which moves the plug. I put a '95 on said '91 and it still reached enough to run fine. If you really wanted to you could probably take the bolts out of the alternator case and rotate the back, though.
Another fun fact, the 91 some prior owner eliminated entirely an idler pulley below the alternator. That meant the belt the books show didn't fit - but one for same year Suburban did. What I can see on this 94, might be able to do the same thing if you had to.
If anyone else has to do one, I forget which year but they'll show it doesn't interchange all the way across 88-95 - but it will. The case is just clocked 1/3rd turn off, which moves the plug. I put a '95 on said '91 and it still reached enough to run fine. If you really wanted to you could probably take the bolts out of the alternator case and rotate the back, though.
Another fun fact, the 91 some prior owner eliminated entirely an idler pulley below the alternator. That meant the belt the books show didn't fit - but one for same year Suburban did. What I can see on this 94, might be able to do the same thing if you had to.
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