6.9 Levelling Valves

[Styria]

I have rebuilt several of those valves for resale on an exchange basis. All units have been bench tested and will work well to the extent that I can provide a twelve months warranty. The 6.9s have two valves controlling the level function on each car for the front and rear respectively. So, just the two valves.

In rebuilding those valves, it is essential to understand their features and characteristics and how they function. I am in possession of the proper workshop manual, and whilst there are many items explained in full, the language used to describe functions and tests can easily lead to confusion and lack of understanding. Furthermore, the manual does not specify measurements of seals, so when one disassembles a valve, you are faced with worn components that are difficult to interpret into actual measurements required for a potential rebuild. I have also found inaccuracies in the drawings of a particular feature of the valve and, additionally, schematic drawings will not help you in determining how the system works. They are utterly confusing.

My prices are well below those charged by overseas sources located in the US and Germany, and I am ready to supply those valves on an exchange basis. I have also noticed in various advertisements on ebay that the operating lever has been turned into a position where they can damage the internal operation of the valve. Any such valve should be treated with suspicion. Regarding efficiency of Air Cells also known as footballs etc. The preferred method of screwdriver insertion as a means of determining a unit's effectiveness is just about totally useless unless a cell is completely collapsed, and you don't need a screwdriver to illustrate that. If a cell even has remaining pressure of less than half, there is no way that a screwdriver will force the membrane further into the unit. Mercedes recommends minimum pressures for both the front and rear units and those minimums can only be ascertained with the appropriate measuring equipment.

All other components of the system can also be assessed and tested for efficiency, such as the pressure oil pump, Pressure Regulator as well as the check valve that is attached to the Regulator. Regards Styria

 

[aussie 6.9]

Hi Michael.
I am interested in exchanging a front one . Mine still works okay but it weeps oil. I have
a spare one off my parts car and I thought I would exchange it. If you could email me the details please. Regards Mark Mckay.

 

[Styria]

These valves were the subject of discussion some ten (?) years ago. Whichever, it wasn't recent. Info on the M100 site was also quite interesting at various times, with owners experiencing a variety of transactions giving cause for concern. One American source sells his units for some $US950.00. Mine are a fair bit cheaper than that.

http://www.topklasse.org/forums/showthread.php?t=327

Regards Styria

 

[Oversize]

I’m surprised MB detailed any valve repair whatsoever. I thought they were replace-only parts? If there was an official overhaul procedure for the valves could that suggest something similar exists for the struts?

Transmission and steering box overhauls were common and one would assume the reason was the parts were too expensive to just replace. When you actually think about it why would their philosophy be any different for hydro parts?? Could it be they felt anyone that could afford the hydro option (or a 6.9) had very deep pockets and would just replace parts when necessary? Or maybe economy of scale was already dictating policy and they didn’t bother doing many repairs on the rarer cars, or systems?

The only hydro parts that were reasonably priced back in the day were the cells. And that was probably because they were used on many other cars and due to their short lifespan of only 2-3 years. Sadly even these have become costly to replace and I can see the need for other options in the future.

 

[Styria]

As a matter of fact, Mark, the Workshop Manual only sets out testing procedures. Rebuilding of components, and parts required, do not receive a mention. A lot of it is trial and error - even the testing procedures shown take some reading and, hopefully, some understanding.

I really don't know what parameters the company used (or uses) in determining the prices of spare parts that may be available for certain components of the hydraulic system. Surely,one would have thought that some spares ought to have been available - one only has to look at various versions of the Unimog Vehicle to see that they also feature hydraulic levelling valves. I have seen them when I was in Austria in 2005. Regards Styria