Contaminated Power steering fluid

Someone stopped by the shop today with a problem with the power steering leaking. I checked it out and the return line from the rack to the pump is rusted through and needs to be replaced. The pressure line looks just as bad and will develop a leak soon too, if not replaced.
While chatting the customer revealed that while stuck with no power steering, he put motor oil into the reserve tank because that’s all he had. It did get him home.
My plan is to replace the pressure line first, then cut the return line below the car (where it can be accessed better). Then use my evacuator,

hooked to the return line from the rack. Start the siphoning and fill the reserve tank with the proper fluid to flush everything out.
I figured that it would flush the reserve tank, pump, pressure line, and rack. Then replace the return line and top off the tank.

What are your thoughts. Will I have to have the engine running while I flush, and do I need to work the steering wheel left and right too.



After your repair, I wouldn’t lose too much sleep about the owner putting motor oil in the reservoir.

Here’s my reasoning

On the big trucks in our fleet, the power steering gearbox manufacturer has a list of approved fluids. And everything under the sun is typically approved, such as Dexron, Mercon, 5w30, 15w40, etc.

On our Mack trucks, the reservoir specifically lists 15w40 as the recommended fluid. But if you look in the actual service manual, just about everything is approved

You sound like you’ve been doing this awhile. Remember back in the days when there was no such thing as “power steering fluid.” They all got atf. And even if you looked in the book, they literally listed whatever atf the car manufacturer used

Here’s what I would do, to keep things simple. Remove those 2 rusty lines. Then slowly move the tires back and forth a few times, with the engine off, to push as much crud out as possible. then install the 2 new lines, add fluid, run the engine, turn the wheel back and forth to get rid of air bubbles, etc.

Sure, you can hook up the machine to exhange the power steering fluid, but I think that’s way too much hassle, and I don’t think it’s really necessary in this case

I would suck it out to. Then drain as much as I could get by removing the hoses. Then I would run the return into a pan and run the engine while turning the wheel. Keeping an eye on the resevoir.