My power steering pump makes a slight hum whether or not I'm turning. The car has 150k miles on it; the steering's operation is perfectly fine. I know it's just worn but usually, they're almost silent. Will changing the fluid quiet its operation/prolong the life of the pump? Or is this just how it's going to be?

 

Change it and hope for the best... depends on how "worn out" it is... PS fluid is easy as hell to change... Have you checked the fluid level? if its too low it will hum. but go ahead and change it and see what happens...

 

No; not low. I changed it before in an 88 Saab 900. I'm very surprised how so many ppl recommend letting the rack run dry while changing it (if they don't have a vacuum tool); you should start pouring new stuff in the reservoir right after it empties and wait for the return line to run clean.

 

Thats what we do... power steering fluid is cheap...