Pully making sound

So i have an 87 b2000 and my pully makes alot of sound after its been running for about 3-5 minutes.
Does anyone have any ideas of what it is?

Which pulley? Guesses would be a tensioner or idler for the timing belt. But first thing I'd do would be wait until it makes the noise, then pull the power steering belt and see if noise goes away. If not, loosen the alternator belt and run 30 seconds. Same for AC belt if you have that in Seattle. And feel and listen to the idler pulleys/bearings for those belts.

No it's the crankshaft pulky makes a screeching sound asfter a few minutes

Pulley*

I'd put my money on the water pump starting to fail. It's the closest pulley bearing to the crankshaft. You can spray water on the belts and see if the screeching goes away.

It's the crankshaft bolt (that big bolt in the middle of the pulley) it needs to be re-torqued, it happened to me (88 B22) and if you keep using it it will wear the keyway.

My fan clutch was bad and makes a squeal and gave me bad gas mpg. Easy fix

No it was missing the washer that goes before the pulley