For Doc J - thanks for the input. I also posed the same question to the folks at Haynes and I've attached their response FYI.
I replaced the PS pump today - was a real bear because of the lack of room to work. I had to remove the upper radiator hose and the fan shroud and fan to make room to work. The worst part was the fluid return line at the bottom due to the factory installed hose clamp. I replaced that with a screw-type clamp. Everything appears to work fine. The unfortunate bit is I don't think the pump was bad after all. I still have a horrible knocking sound in the vicinity of the PS pump when I start the vehicle that persists for 2-4 seconds, then stops and has no appearant effect on the truck.
Again, thanks for the input, it did help with the job. Right now, I'm sore and still have very dirty hands.
Thank you for your inquiry.
Its not absolutely necessary to do this to
repalce the pump. But to bleed the system once you have put a new component in
the system is recommended. When you first start the vehicle after a new
component has been installed in the power steering system there is air in the
system and it usually foames up. If you put pressure on the pump at his point
(such as turning the wheels especially if they are large wheels and tires)
there is the outside chance that you could damage the pump. I hope this helps.
Again, thank you for using Haynes
Sent: Mon 3/2/2009 11:08 AM
Subject: STEERING PUMP REPLACEMENT
What is the purpose of removing front wheels when replacing
the power steering pump on a 1997 Ford Ranger?
Haynes Repair Manual for Ford Pick-ups covers PS Pump replacement in Chapter
10, section 29. Step 3 states "Loosen the front wheel lug nuts. Raise the
front of the vehicle, support it securely on jackstands, block the rear wheels
and set the parking brake. Remove both front wheels."
I do not understand what role this plays in replacing the PS Pump. Any ideas?
Is this really a necessary step? The vehicle is a 1997 Ford Ranger, 4 cyl 2.3