E36 M3 squeal - please help

[brklyn]

Hi,

First post. When pressing throttle, get this squealing. Have a theory, but curious if anyone recognizes the cause and can point me in right direction. Would like to fix this myself.

Thanks in advance

[RRSperry]

Idler pulley or belt tensioner. Possibly the alternator.

[bluptgm3]

Or belt, due to a dirty/failing tensioner/tensiorer pivot.
Remove the belt, remove test the tensioner pulley and idler pulley, they should be smooth and quiet and should stop rotating quickly due to internal lubricant and seal stiction.
Take the tensioner off and apart, lube the pivot shaft and bearings and reassemble and reinstall.

Often, you can use a Mechanic’s Stethoscope to located the errant part, or if no one part stands out, it is the belt and a ‘lazy’ tensioner that is the cause.

https://www.homedepot.com/p/Lisle-Me...2500/306763901

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[Hova]

Idler pulley or belt tensioner. Possibly the alternator.

This.

Pop the plastic cover off the tensioner, use 8mm allen bit (or 10mm, I forget) on a break bar on the belt tensioner (through it), turn it counter clockwise. Take the belt off the alternator, and you can then spin each by hand and find out which one is squealing.


https://www.autozone.com/repairguide...00c152801b22fb

I usually just re-pack my idler pulley and belt tensioner with grease whenever I take the belt off, or every few years. They have worked flawlessly for 10+ years.

[NeilM]

Idler pulley or belt tensioner. Possibly the alternator.

^^^^
This

There's a distinct metallic tone to the sound, so not likely to be the belt.

Neil

[brklyn]

Thanks for all the replies.

It's likely the alternator (maybe bearings or pulley?) as it started after recent replacement. My mistake for getting one off ebay. Was only thing replaced.