I will be changing out the high pressure and return lines of the power steering pump on an '88 300E this weekend. Both lines appear to be leaking. My question is this. For purposes of flushing the old fluid, is it ok to cut the return line, start the motor to let the pump push out all the old fluid from the steering box? Or will this damage the pump and/or the steering box?
I have the CD manual, but cannot find the prodedure for changing out the hoses. I appreciate any advise.

Regards,

Marks88

I would not recommend starting the engine with the hoses disconnected. This might easily get out of hand, with damage to the pump a possibility.

I would just disconnect the High Pressure hose at the end opposite the pump end, on the other side of the oil pan (not sure if the location is the same as my V8). Then let if a drain out in a bucket, doing the same for the return line. In addition you will need to remove the P/S fluid from the reserviour ala Topsider or similar device, this should move most the the fluid.

I think a Tech may have a better method???

9 out of 10 times it is just the hose clamp that causes the leak...are you sure that you need to replace the hoses and that the problem cannot be solved by easily retighten the hose clamps?
Untighten the hose clamp a bit, shove the hose a little further on the pipe and tighten the clamp again; normally that does the trick...

greetingz,

MBenz,

The clamps may only needed to be tightened on the return line, however the high pressure line is also "wet and spongy" looking. I know that it needs to be replaced and while I was there, I will replace the return line as well.
I bought the car used, and I'm guessing these are the original hoses. Thanks for your help.

Marks88

Have you tryed cleaning those hoses with a good degreaser? With my hoses, the years of road grime + fluid leaks made the under side of the engine look hopeless. With a clean engine, diagnosis is made much simpler and you will also make yourself and mechanic much happier.

Did you perform any work yet?

roas,

Yes, I have changed out the P/S hoses. Did it last weekend.
It wasn't a bad job at all. It was a little slow going, due to inexperience, and lack of the proper tools (some funky angles to get to). But all is well, fresh fluid, no leaks and the groaning sounds when I would turn the wheel are gone. I appreciate your help.
Next project, Tranny filter change.......

Regards,

Marks88

Marks88,

How were you able to get to the high pressure line on the top of the steering box? Mine seems impossible to get to. Did you drop the steering box itself?

Im assuming my car should be similar, 90 300CE.

Any input is greatly appreciated. Thanks in advance!