I believe I have a power steering problem. Truck is a 99 4 cylinder with 5 speed manual and XLT trim. I have had the truck for several years and the power steering pump has been moaning and groaning the whole time, but has continued to work just fine. Today I suddenly started to get a shudder when going around corners, and the shudder seems to get worse with speed and turning angle. As soon as it happened I popped the hood and it appears that power steering fluid has sprayed on the inner fender. It's kind of hard to tell where it came from, but it looks like it may have just forced its way out the cap, but I suppose it could be a leaking line. The reservoir still appears to have plenty of fluid. The power steering works just fine when the truck is sitting still or moving slowly.

What's my best course of action here? Is it likely that it could be a line leak ( I could clean and look for leaks), or is it more likely the pump?

 

Fords are notorious for PS pump whine.

The shudder sounds like it happens under load and it could be:
- A belt skipping due to a weak or gunked up tensioner arm
- A bad pump
- Hoses that are no longer stiff and allowing for the fluid to swell them and acting like a mini expansion chamber.
- High friction in a suspension part like a ball joint
- Some combination of the above

Here is what I'd do.
- Put the front end up on jack stands.
- With the hood open have someone turn the wheels back and forth trying to recreate the condition
- Look for the belt to be jumping during this time
- See where the fluid is coming from
- look to see if the hose are swelling or moving (they should move only enough to allow for engine rocking)
- Engine off and key in steering unlock position. Rotate the wheels by hand and see if the friction is high.

TIPS:
With the age of your Ranger and what you've said I'd suspect the pump or hoses first.
Chances are only flushing the fluid won't have any effect.
Remove the belt and work the tensioner through it full range about 10 times. (they often don't move much and debris builds up inside them and so they can allow the belt to slip if under high load. This can be felt as a shudder. But... its generally not the root cause)
If there is a difference when the fluid is hot vs cold its a clue. (fluid is more viscous when cold)

My Ranger has 153k miles now. When I got the truck at 150k the PS pump had a bit of whine but not an abnormal amount. I flushed the fluid twice and it feels firmer and smoother. The fluid even still looks brand new and is cherry red. But the noise is pretty much unchanged and is most noticeable under load. Like when turning and not moving.

 

Thanks for the tips! Interestingly, I have not been able to reproduce that problem since reported above, and no further fluid seems to have been spilled, so I have no idea what is going on. The truck is not a daily driver for me, but I should have some time this weekend. I'll check the pulley tension and maybe flush the fluid. Since I use the truck for hauling dirt bikes, it does see a fair amount of mud. Maybe I did get debris lodged in the tensioner.

 

Also if you turn the wheel with the truck off it can suck in air past the seals. (not one of fords smarter designs) and turning the wheel back n forth (or normal driving) will eventually work the air out of the system. I suppose if it works a big bubble out at once it could spray fluid out the hole in the cap. Id just keep driving it and checking power steering levels.