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Pressure from HPF pump to valve unit

Started by BCK1963, 18 June 2023, 09:24 AM



today I noticed wet hose connections at the power steering pump but eventually it turned out to be the pressure hose from the HPF pump to the upper valve unit on the reservoir which leaked. The hydraulic oil rinsed down the hose to the pump's connection which is situated directly above the power steering reservoir lid. From there the oil rinsed further down to the lowest point.

Before I start digging into how to get a new piece: Does anybody have experience as to whether is is still available new or as repro from a reliable source, preferably in Germany?

   Thanks   Bernd

1976 Merc 6.9   Magnetit blue


Can you post a picture?  I might have one.  For sure, i have a box of all that tubing someplace..  The problem is that I'm moving and all my stuff is in chaos.  If you're not in too much of a hurry I can keeps my eyes open till I stumble on it.  Cheers,
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0


Thanks Dave, but I need it quick as I don't wsant to take the risk of driving with an already leaking pressure hose.

It is still available new at MB for as little as appr. 360 €. Not exactly a bargain.
I will check with reliable hydraulic shops.

1976 Merc 6.9   Magnetit blue


Hello Bernd,

the pressure hose is still available, but very expensive. I had just bought it because I still had coupons. I mean the price was over 200 EURO. I would also try the line in a hydraulic store to make new. Many greetings
1978 Mercedes 6.9 # 4616 - black/black leather
BMW R 25/3


Hello Bjoern,
thanks for replying. AsI said, they want to charge me 360 €. I am trying to save on that.
Will keep you posted.

   Regards    Bernd

1976 Merc 6.9   Magnetit blue


Also still available from the MB Classic Centre, I just checked with the one in Irvine, CA:

116 997 96 82 = $174.00 USD List.  They may also offer you some discount off this price if you ask nicely 8)

I think you guys in Europe have a separate Classic Centre there so you should be getting these prices there too I am sure?  Then shipping will be way cheaper as well.
1977 450 SEL 6.9 - Astralsilber


'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,


Thanks guys, very interesting. For 129 $ I wouldn't start actions with hydraulik shops.
But looking at the hose in Daniel's upper ebay link brings up another problem for me.

The joints of my hose are as pictured below and as such the link to the pump is different.
I learned from the car's repair records that a new pressure pump has been installed in 1996. On that occasion the joint may have been modified with a 90 ° link as pictured below. No idea what the original setup looked like.

If I removed the modified rectangular joint on my pump it would mean that the above ebay hose would enter horizontally and would be located directly above the power steering reservoir lid, thus making opening the reservoir more or less impossible.

btw: On the ebay hose, advertized as NOS, the hose is fixed to the joint with a hose clamp. I am not an hydraulics specialist but the hose is supposed to bear more than 100 bar and I'd find a hose clamp pretty suspicious in that place. Makes my wonder if it really  Mercedes OEM material. But I may be wrong.

I'll stick to replacing my hose with a similar one. I have already tracked the original hose supplier and have received 50 cm of the modern successor of the original hose. Now hunting for the joints.


1976 Merc 6.9   Magnetit blue


Sorry, can't get pics to appear, hopefully later.

1976 Merc 6.9   Magnetit blue


Job done.
As I wrote previously, a previous owner did a slight mod on the pump joint by installing a 90 ° angle which permits access and jointing from above.
The new unit now costed 19.50 € in a hydraulic shop, instead of 360 € at MB. The successor of the original hose, supplied by the original supplier, was used. Fine with me  ;)

1976 Merc 6.9   Magnetit blue


Hello Bernd, good to know it is possible to rebuild the hose using a conventional hydraulic shop. My feed and high pressure lines are leaking. I added a UV dye to the oil and found quite the mess over the power steering pump. Without the dye it was not easy to determine which thing was leaking.

Very helpful post - thank you.
1979 450 SEL 6.9 (#5532) - silbergrün metallic


Hello Andrew,

glad to hear that my post was helpful.
Mercedes things often are not as special as one tends to think. Also MB didn't make the pressure hoses themselves but bought them from more or less standard hydraulic shops.

Nonetheless, I was in contact with and have been to a couple of shops and got different responses before I had the hose eventually done in one shop.
So knowing what you want and making sure that the shops can deliver that is essential.

btw:  I love the Silbergrün of your car.
My first BMW, a 1977 1502, wore Resedagrün, which is more or less identical with MB Silbergrün. And it was a 6.9 in Silbergrün over dark green velour which happened to be too expensive but which ultimately made me seriously look for a W116 and made me end up with mine.

    Good luck    Bernd

1976 Merc 6.9   Magnetit blue