I want to flush and refill the power steering system on my '86 300E. Is there a simpler way to do it other than disconnecting the return hose, running the engine and refilling it from the top as it pumps it out the bottom? Is it necessary to turn the wheels lock to lock while doing this? Is there a bleed screw anywhere in the system for removing air? What's the capacity of the system, and how much should I figure on to thoroughly flush it?

What are the recommended fluids I can use in this system? A local wholesale/retail European parts house sells ATE and, I think, Pentosin. Are these ok for MB's? What's the largest number of question marks I'm allowed in a single post???

Thanks for your help

Use the power steering fluid that you get at your local parts store.

If you want to thoroughly flush the system and change fluid, removing the return hose and dropping it down to a pan is the easiest way. You described it as if it were some huge project. It should take no more than 10 or 15 minutes to remove the hose, drop it down into a drain pan, have someone start the car, pour two quarts throug the system while they turn the wheel, tell them to stop, reconnect the hose, fill the system while the helper is turning the wheel to bleed the system and put the reservoir top back on.

This is no big deal and is absolutely the best way to clean the system. There is no bleed screw because you don't need it. If you will read the manual you will see that bleeding is simply a matter of turning the wheel back and forth lock to lock a few times, then topping off the fluid level.

This is even the method that is the correct answer to a question on the ASE test. I can't think of any way that is any more thorough and is quicker and easier.

Good luck with it,

Pentosin and such is for cars with a special hydraulic pump circuit for steering and braking assist. Sometimes this sort of hydraulic sytem will be expanded to control suspension dampers and such. This stuff is a very thin, clear fluid. Must be very special indeed, considering the price!

Many Audis and BMWs have this type of setup.
Standard P/S oil in one of these systems is fatal, and a very expensive mistake to make. [No need to ask me how I know this...]

Anyways, not an issue in this case...
Don't forget to get a new filter.

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1986 300E 5-Speed 240k mi.