M20 LOUD squeal on some cold starts (solved again)

[Sea Aych]

Just picked up an '89 325i a few weeks ago, and been baffled over this issue as it's almost impossible to recreate...it just happens randomly. On a cold start on warm days (usually after the car's been in the sun for a little while), sometimes (maybe 20% of the time) there's a seriously loud squeal that lasts maybe half a second when the engine catches and revs up. It immediately goes away and there are no issues/noises after that.
It sounds like a belt (rubber slipping on metal).
Does anyone know what it could be? I'm just baffled because i can't get it to happen again when i try. It seems just to do it randomly during those warmer days. Sometimes it happens sometimes it doesn't...
Any help greatly appreciated.
Thanks!

**NEW QUESTION in last post - didn't want to start a new thread

[Scallywagon]

It probably is just that; a belt. Tighten all of the auxiliary belts and, report back

[Sea Aych]

It probably is just that; a belt. Tighten all of the auxiliary belts and, report back

Yeah, i'll try it this week. I'm just curious as to why it only does it under certain circumstances, but then decides it doesn't want to. I was just worried that it would be pointing to a bigger issue

[Scallywagon]

Yeah, i'll try it this week. I'm just curious as to why it only does it under certain circumstances, but then decides it doesn't want to. I was just worried that it would be pointing to a bigger issue

Because rubber is highly susceptible to heat and, moisture. Expansion and contraction, if its not tight enough then you'll get slipping

[Sea Aych]

Belts look in good shape after a quick look last night, so I tightened them up a bit, but they didn't really need to go very far at all...Hopefully this works - i guess i'll find out soon enough. Thanks ppl!

[cabriodster87]

I've noticed that sometimes the starter is not disengaging from the flywheel fast enough. Quite a screechy sound.

[Sea Aych]

I've noticed that sometimes the starter is not disengaging from the flywheel fast enough. Quite a screechy sound.

Yeah, it actually is really screechy..what does ^ mean on my end?

Tightened the belts (they're in decent shape too), but the noise is back, just as random as before.
Probably will replace the belts i guess...It's not too expensive anyhow

[Shanes325]

5speed? Could be a throw out bearing? Had it happen to me any couldn't find the problem. Then... 6 months later it starting chattering. Repaced and never had he noise again.

[Sea Aych]

5speed? Could be a throw out bearing? Had it happen to me any couldn't find the problem. Then... 6 months later it starting chattering. Repaced and never had he noise again.

autotragic, but i'm swapping it now. So we'll see if it happens after that.. hoping it's just the AC or any other easy to replace belt :p

[Sea Aych]

Update: got a video w/ sound of it finally: happens pretty consistently now when it's below 45 degrees outside and it's been sitting all night. The video stops right as the sound stops btw, doesn't continue after that.
Any ideas? Thanks!

[Swanny]

M20 LOUD squeal on some cold starts

Spray some hair spray on the belts to rule them out.

[Tom.]

sounds like the starter to me.

[Sea Aych]

Spray some hair spray on the belts to rule them out.

not a bad idea, actually, but after what tom said, some quick youtubing shows that people have a similar sound with "starter squeal".

sounds like the starter to me.

Which bit?

[peytonracer4]

that sounds like a starter in the video. not a belt.

[Sea Aych]

that sounds like a starter in the video. not a belt.

How urgent is this....?