Squealing belt info.

[Mark]

A few days ago my alternator/water pump belt started squealing at start-up/idle. It progressively got worse until it was squealing all the time. I assumed it was a loose belt so I checked it and it was properly tight. I replaced it anyway and it was fine for about 15 minutes and then it started squealing again. My turn signal seemed to be flashing quicker than normal as well (not as fast as when one of them is burnt out). I checked the voltage at the battery when the engine was running and it showed 16.5v at idle and 18v when revving the engine. Oh, and the battery acid was boiling out of the battery as well. So the voltage regulator in the alternator was bad. I replaced the alternator with a spare I had and now the belt doesn't squeal anymore and the voltage is correct.
Anyway, if your belt starts squealing, check your voltage output of the alternator since apparently that can cause a squealing belt. I don't know if a high voltage can cause the alternator to be difficult to turn, causing the belt to slip.

[MrWrench]

Thank you Mark! I recently replaced my alternator with a cheap eBay 60 amp alternator and my belt has recently started squeaking.
When I was changing the oil, I noticed both belts were pretty tight. I think I will drive my wagon to work tomorrow and check the battery voltage after work.

Thanks again for the tip!

[Petros]

that is correct: if the belts are tight and in good condition, likely cause is dragging alternator. this can be seized bearings, or a bad voltage regulator that allows it go full "on", that causes more drag on the alternator. good thing you fixed it, many keep driving it until the battery gets burnt out. than you get to replace the voltage regular AND the battery.