Help me diagnose this noise! (video)

[pvrse]

Happens on startup. High pitched. 1990 e30 325i m20

https://www.youtube.com/watch?v=N6XPsGPf7ao

[LateFan]

mother-in-law

back seat

[pvrse]

You know what it could be?

[LateFan]

oh....um....

Slipping belts?
Starter gear hanging up too long?
Starter itself? (as it slows down the noise dissipates)
That huge blower you bolted on?

Actually it sounds more mechanical than belts to me...

Is it only on start-up, or does it do it when you rev?

[pvrse]

Start up I believe. Reved and couldn't really hear it.

This noise went away after starting it up a few different times. But I'd like to know why it happened and if it will again

[LateFan]

If it did it when you revved, I'd be more worried about timing belt hardware or a tensioner or something like that. Flywheel or clutch rubbing, steering pump, AC compressor...

But start-up only seems starter-related, or something cold when it first spins up, and the bearings or bushings are tired.

[pvrse]

Okay. I just started it again after 30 minutes or so and it didnt happen. revs just fine, very strong.

Probably has to do with the starter? Who knows. If you have any more ideas let me know.

[zig553]

Mine has done that for the last 5 years I've owned it, but only sometimes. I noticed it gets bad/louder on really hot days. I think it may be just the starter grinding somehow? But I always said I'll just fix it when it breaks. Which it has yet to after 5 years. Only ever makes the noise while starting.