My 89 f150 started squeaking under the hood for the first time today. Yesterday I had the bed loaded down with 2000 pounds of landscape stones.. not sure that would have caused an issue but it wasn't making the squeaking noise yesterday. The squeak only is present when idling or when coming to a stop. Once I give the truck gas the squeak goes away. I assume a belt is the source of the noise. The squeak is loudest at the power steering pump. Is my power steering pump going out on me? Is there a solution to getting rid of the squeak?

Any help/suggestions greatly appreciated!

 

worn belt
mal-adjusted belt
low PS fluid
PS pump issue
idler pulley on belt loop or other pulley driven unit (a/c, smog pump, alternator, etc) on the same belt.
water pump

and so on, you need to give the belts a good visual and then listen closely when it is squeaking...
be careful of moving parts ...

 

Pry up on the water pump pulley. My water pump wasn't leaking (yet) but the bearing was so worn out it was getting the belt out of line and squeaking on the other pulleys. Replaced the water pump with a new one, all is nice and quiet

Yours could be something that Kd3pc suggested but mine was the water pump, like he listed also as a possibility.

 

Had belt squeak going on, and was amazed when I replaced the belt tensioner at how much more tension that new one had over my (80,000mi) take-off original. If your various pulleys all inspect OK and the belt looks good, don't discount the fact that the spring in the belt tensioner does lose its strength over the years. Pretty cheap to replace.