Gramps47

Just had my alt and accessory belts tightened as one of them was squealing pretty bad on startup. Seem about right now....but, there is still a very slight squealing sound on occasion when I raise a window or turn on the fan or some other electrical draw. Thinking the alternator could be failing. Any other possibilities.

Thanks....car is a 91 S2

peanut

the problem with tightening belts is that it puts an increased an unaccustomed stress on the bearings of the various components .

There have been many instances of water pump and alternator bearings failing soon after new belts and belt tightening if they have been over-tightened.

I suspect the noise may well be your alternator bearing but you may need to use a stetoscope or a wooden rod /screwdriver held to your ear to confirm it. The alternator bearing may have dried out and need relubing or replacing.
It would be worth using an ampmeter to check your current draw of your electric windows, wipers etc and other heavy electrical loads and check your alternator output is to spec as the brushes may need replacing.

My 89S2 squealed daily for nearly 3 months one winter and I ignored it then it stopped squealing for nearly 4x years ! it has started squealing again a little occasionally so I expect i'll have to look into it when the weather improves.

Jfrahm

The S2 and 968 particularly seem to have a problem with the alternator belt squealing. There is a pulley mod to add some wrap around the alternator, and/or some of the turbo folks use a smaller alternator they claim is easier to rotate. That involves some grinding on the alternator and/or the mount.

That belt tension spec is scary tight as per the factory manual. Tighter than I am comfortable with for alternator and AC bearing health.

You can try some belt dressing to quiet it down or at least identify the issue. Belt dressing won't change a bad bearing noise.

-Joel.