Help identifying idle noise (with video)

[RangerJoey]

Hello,

This has been going on for sometime now but the truck hasn't been driven in ages. Now I'm looking to move from the suspension onto the actual engine. About to change the oil and I know there's a million other things this 4.0 needs, (plugs, wires, air filter, MAF/Throttle clean, EGR, PCV and so on), but can anyone help identify this kind of "electric motoring" noise going on? Forgive the video quality. I tried panning the entire engine bay but the noise I'm referring to comes into play clearer the closer I get to the rear driver side, (around 0:50 mark or so). It's really hard to pinpoint with the engine moving all that air.

Something is making me think steering and I wouldn't mind swapping the power steering fluid this weekend anyway since that's like number 24 on the list of a kabillion things this truck needs.

 

[1990RangerinSK]

Power Steering pump. They tend to whine like that, especially when the fluid is low. Best way to confirm would be to take it for a drive, and turn the steering wheel. The pitch will change as the pump pumps fluid to turn the wheels.

 

[RangerJoey]

Thank you! I was going to do the turkey baster method but I might really take off the return line and do it thoroughly if it's that loud.