Thanks for all the feedback; I think I have the problem licked. But first...
The shop I work at subscribes to a service called "Identifix." Basically it's a nationwide information sharing service that you access using a software package. You log on, enter make, model engine, etc. and then enter the trouble code you've found or a symptom. You then see dozens, sometimes hundreds of case histories of cars just like the one your're workign on with the exact same or very similar problem. System users can see what other shops tried and what eventually fixed the problem. So it's a very handy diagnosis tool, especially when you get a make/model car that you're unfamiliar with. It can be a huge time/money saver.
Well I entered all the info for my 07 Entourage and learned that poor power steering assist was not usually the pump or the rack -- it was the fluid reservoir. (As some responders pointed out.) Well there's a very fine mesh screen that separates the upper portion of the reservoir from the lower portion. Fluid returning from the rack/PS cooler is dumped into the reservoir but must then pass through the screen to enter the pump.
The screen may not be filthy and black or ever look clogged at all. But removing the reservoir, emptying it, and cleaning the screen with Brakleen or another solvent and then blowing the screen dry with compressed air is supposed to do the trick.
A lot of shops reported replacing the pump, (some did this twice), and then getting desperate and replacing the rack. Without fixing the problem!
At some point somebody discovered the reservoir screen issue and that did the trick.
Well last week we had a customer come in with about an 05 Amanti with lack of steering assist. Raising the car I could see that the pump had already been replaced and showed my boss. He said I guess it needs a rack. I convinced him to let me try the fluid reservoir cleanout trick since it was pretty easy and could be done from under the hood. He agreed and we were both amazed when cleaning that reservoir completely fixed the problem.
That had me pretty fired up and I was eager to try the fix on my van asap. I stayed late after work to try it and I'm sorry to say that it did absolutely nothing for me. Major bummer, let me tell you.
So Saturday I ordered a rebuilt pump and also a new Gates hose assembly. I went to the shop yesterday and replaced both of those parts and everything seems good now. I have to say that replacing that tiny pump is quite the bee-otch. Access is pretty nasty and getting at the top mounting bolt made me use my full swear word vocabulary.
It will all be worth it, though, if I leave for work tomorrow morning and full power steering function has been restored. It's supposed to drop to 25F tonight so I'll know one way or the other. LOL
Last edited by Pete in PA; 12-12-2016 at 02:49 PM.