What is this sound coming from my supercharger? (video)

[Danny318]

A little backstory

Supercharger is 5 or so years old but only had about 10k miles on it then sat for 4 years and then finally put back on the rebuilt motor. It didn't make this sound originally but made it since the rebuild. I took it off and replaced the rear needle bearings (they were fine though) and everything looked good.

It doesnt make this sound if you turn it by hand.

It doesnt make it with the engine cold.

It makes it mostly around 4k rpm and up, accel and decel.

The belt and tensioner are brand new, but I'm still suspicious of the belt because its not that tight and it can be seen 'vibrating' near the supercharger pulley - could it be belt slip? The boost is a bit lower than I expected..

I would think if it were a bearing or something inside it contacting it would make it at any RPM hot or cold, so I don't know. I want it to be the belt getting a little loose when it warms up and thats the problem, but thats wishful thinking.

Please share any ideas! Thanks




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Actually looking at the video now around 22 seconds in where you can see the belt - the sound goes perfectly with the vibrating belt. I still can't picture what is creating that awful sound though...

[xxxJohnBoyxxx]

Idler pulley maybe? From the video I can't tell exactly where the noise is coming from.

[Danny318]

Me either. I replaced all the pulleys though. I have a new alternator on the way in case it is that.

[Monolith]

Do you have a stethoscope or a long screwdriver that you can use to help isolate the noise?

[M-technik-3]

Where in Mass are you? It does sound like the idler pulley but might not be. Where did you get pulleys from?

[Danny318]

I know right. I got two new idler pully's from Jim from D/A - tried them and the old ones, and put in a new idler that goes on the tensioner. Its not them.

The only thing I didn't replace yet is the alternator so thats going in this weekend.