w124 power steering fluid pipe

[Smiley]

I have been doing a small amount of patching up on the n/s inner wing today. To get at it I removed the headlight and indicator - and then noticed that the pipe running from the PAS fluid reservoir to the PAS pump has perished badly where it sits in the inner wing as it leaves the bottom of the reservoir. Obviously I am going to get a new pipe and replace it - do I need to take any special precautions? I realise I will need to drain the power steering pump and the reservoir and re-fill - what is the best way to do this - any tips please?

BTW it is worth popping the n/s headlight out on your w124 and taking a look - mine is 14 yrs old and the pipe looks like it is about to leak, not sure why it has deteriorated so badly.

Also worth having a good look around the inner wings - I spotted one small rust bubble - in the end I have a 5cm square hole in the inner wing just next to the base of the PAS reservior - caused by moisture and mud being held there by the plastic inner shield. Easy enough to repair.

 

[lynall]

I should imagine easiest way is to find the lowest point of the pipework and undo the joint and drain into a pan, i think however you do it you are going to get messy.

If youve got a vac fluid extractor you could push the vac pipe down the reservior rubber pipe but i still reckon you will get dirty.

But if you are capable of welding a repair patch in this wont faze you.






Lynall

 

[Smiley]

Thanks Lynall, i was not sure if it needs bleeding when being re-filled?
Never touched the PAS fluid ever; made me wonder if it ought to be changed after 14years?

 

[Number_Cruncher]

Are you sure it's the PAS reservoir? The reservoir for the power steering is usually on top of the pump itself.

On the n/s inner wing, I think it's more likely to be the reservoir for the self levelling rear suspension (if fitted to your car).

It's really easy to change the oil in the SLS - just point the return pipe into a catch container, and run the engine - the fluid flow is really slow, and you can just top up the loss in the reservoir with new self levelling suspension oil as you go.

 

[Smiley]

You are dead right NC. I have looked again and whilst it looks like it is connected to the PAS it is indeed separate and it is the self levelling fluid reservoir. The Haynes manual recommends de-pressurising the system by bleeding 1/2 litre out from the control valve on the rear axle. Is this not necessary? All I want to do is change the pipe that looks the worse for wear. It is a braided rubber hose and it seems to have decomposed (best way to describe it) at the reservoir end. I dont know if there has been a very slight weep at the joint with the reservoir and this has caused the decay or whether my waxoyl sprayed down there has eaten the pipe. Either way it needs replacing.
Do I need to get the fluid from MB?

 

[mercedeslover]

Also change the pas filter @ the bottom of the reservoir. Very straightforward!
I have also painted the cooling pipe for the PAS in front of the rad.
It is always the little things.

 

[Smiley]

There are two separate sets of fluid here - one for the self levelling and one for the PAS. Did not know there was a filter in there; does anyone EVER change them? How is the PAS drained?

 

[Number_Cruncher]

The pipe from the lower end of the reservoir on the inner wing is the pump's suction pipe, and isn't under pressure. Therefore, there's no need to de-pressurise the system before disturbing it. What I would be tempted to do is to route the return pipe into a catch container, and run the engine for a bit until the tank is on the verge of emptying before replacing the braided hose - this will prevent too much fluid leaking away. If you've a Pela or other oil vacuum pump, you couold empty the tank using that.

The filter in the power steering tank is easy to change - it's just a matter of releasing the nut on the post in the centre of the reservoir. Flushing the power steering oil is a more fraught affair - the oil pumps out really quickly with the engine running, and you definitiely need an assistant to start / stop the engine and work the steering to flush the old oil out.

For the PAS, in my '95 E300D, I used 2 litres of A0009898803oil, the filter was A0004662104

I don't have the MB numbers for the SLS oil readily available, and there isn't a filter as such - just a strainer which fits inside the SLS reservoir filler cap.

 

[Smiley]

Thanks NC again.
Great that I can go ahead without de-pressurising the system - going to make it a whole lot easier - I just need to drain the reservoir (I will get a suction thing) replace the pipe and then re-fill.
Does it self bleed or do I need to do something once it is re-filled?

 

[Druk]

Do you have the washer reservoir on the O/S inner wing? Undo the large thumbwheel and remove. The bottom sits in a large grommet and that's a rust prone area.

 

[Number_Cruncher]

Does it self bleed or do I need to do something once it is re-filled?

When the rear suspension is at the right height, fluid is circulated from the pump to the level control valve [at very low pressures], and then back to the reservoir, so, it does self bleed. You just need to top up the oil.

The flow is so slow and benign that you can easily divert the return pipe, and flush some new oil into the system.

 

[Algoritmus]

Hi Smiley,
I have the same problem with that hose, do you know the part number of it ?

Cheers

A

 

[LastMinute]

Item 5 here? (Note that that diagram is for a LHD car, which is why some of it might look to be the wrong way round. But the parts are all applicable to both LHD and RHD.)

 

[Algoritmus]

Yes it is ! Thanks very much !

Attila