91 240 160K miles. Bought with written "bad water pump" diagnosis from Volvo dealer. Engine squeaked / screeched at idle and up. Pump pulley tight & didn't think it was bad but replaced anyway.

Thought the screech was gone but now it does it sometimes - say in 2 out of 5 starts. It usually (but not always) seems to go away on the road and after a complete warmup.

The alternator came loose recently and I thought it was that but the noise is back.

The crankshaft pulley seems OK - I read here that the vulcanizing breaks and it spins on the inner.

Sometimes it sounds like it's coming from the motor.

I should have removed all belts and ran the motor when I was replacing the water pump but was fooled by the dealer diagnosis.

Possibilities:

1. Bad belt(s): Could be but silicone spray doesn't stop the squeak.
2. Crank pulley: Maybe I just missed it in the inspection.
3. Bad alternator bearing: doesn't sound like it's coming from there.
4. Bad PS bearing.
5. Bad timing belt: It looks OK but I don't know how old it is.
6. Something bad in the drivetrain?

If it did it on every cold start and then stopped every time I'd suspect a bearing or other problem with the cam. I've not had this kind of problem with any of my 240s.

Other possibilities?
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240s: 2 drivers and some parts cars