so my 86 silverado is making a horrible whine from the belt slipping on the pump pully. ive swapped the pump already and its still slipping. what else could be causing it. and i know this isnt about a 3rd gen but theres nothing wrong with my camaro at the moment and this noise is driving me insane.

 

I know you said you had replaced the pump, but what about the pulley or belt? If the belt is glazed, pulley's warped, or pulley's not correctly aligned with the rest of the accessory pulleys, that could be your issue.

 

I concur with 1A Dan. Replace the belt (never a bad idea). Check belt/pulley alignment. if anything isn't true then you are going to have noise. I have never had a bent pulley make a noise, but it could.

 

I replaced the pump and pulley at the same time, the belt looked good to me but ill try replacing it today after work. I thought it might be the steering box or maybe air trapped somewhere in the system or maybe even the fluid. But I don't know much about powersteering to tell.

 

forgot to mention it only makes the squeal when turning.

 

just to let u guys no, it was a stretched belt. i replaced it and now it only whines a lil bit at startup.

 

recheck your fluid levels - using the pump will settle the fluid into the system, and now it might be low.