6.9 hydraulic fittings

[s class]

The 6.9 suspension oil tank supports two units on top of it - firstly the cast iron pressure regulator, and then attached to it, the alloy distribution valve. The distribution valve is the unit to which the dash pull-handle cable connects. The valve has three main ports, plus a return. The three main ports are :

a) incoming flow from the master sphere
b) Normal ride height control pressure supply which feeds the front and rear levelling valves
c) High ride height control pressure supply which feeds the front and rear levelling valves

The 4th port is a return that vents via the pressure regulator back into the tank.

Anyhow, the port I've described as a) above, is in the form of a 14mm hex fitting to which the steel line from the master sphere connects. But it is more than that, the end of the fitting that screws into alloy distributor incorporates a ball-valve seat. In trusty rusty's case, this fitting must have got lost at some point in the past, and its been replaced by a horrible home-made affair - which doesn't operate properly as a valve - one of the many reasons that trusty rusty didn't pump up before.

This fitting is unavailable separately. I took the corresponding item from the red car, and sent it to our local hydraulics place to be copied. These are the results : (in each case, copy on the left, original on the right)







I was absolutely astounded at the quality of work and precision of the duplication. I would like to ask our Australian members what they would pay for work like this - remembering this is not a standard fitting - it has been custom manufactured.

Now, there is a VERY sad end to this story - I came to fit this new part to trusty rusty and discovered that, being an earlier car, the distribution valve has a different pitch to the thread, and this later style fitting will not fit.

 

[Styria]

Hi S-Class, the first problem would be to find an engineering shop ccapable of doing the work. Right at this moment, I would not know where to start.

The price - one would look at a minimum of $A250.00, but I would endeavour to look for an alternative - something like an ordinary bolt with the same internal thread as on the regulator body, and then machine the bolt itself to copy the dimensions of the original item. I reckon it could be done that way.

Quite frankly, you must be shattered at the outcome of all this. My commiserations go out to you. Alternatively, buy a complete second hand unit - THEY ARE AVAILABLE ! Regards Styria

BTW - did you ever manage to locate a dust boot for the front and rear levelling valves ?

 

[s class]

styria, I paid R50 for the fitting - about A$7 or so. So no big loss. Just a frustration. At least artisan type work is cheap here in South Africa.

The dust boots I'm using are serviceable, though the rubber seems to have degraded ever so slightly with exposure to hydro oil. They are holding up though. The boots I'm using had to be modified by trimming with a stanley knife - I would prefer to find something that could fit without modification. I have not completely given up on that effort yet.

 

[Styria]

S-Class, that price is unbelievable - at that sort of money, you wouldn't care, would you ? BTW, any thoughts on the "bolt alternative" that I have mentioned. Regards Styria

 

[WGB]

Sounds like you need to get another one made with the correct thread.

Excellent work.

Bill

 

[John S]

S class, if the problem is the one-way valve not working and originality is not a concern, it should be very easy to have up a standard hydraulic one-way valve installed a few inches down the line.

 

[s class]

Thanks guys - three suggestions :

a) machine a suitbale bolt to the required shape
b) get another fitting made (it is cheap anyhow)
c) investigate alternative valve arrangements

I'm off to the hydraulics place just now to discuss this with them. I fancy b) at present, but I'll hear what they have to say.

 

[s class]

Well with some embarrasment I explained my situation to the hydraulics place. They are busy making up a new fitting with 1mm pitch as opposed the previous 1,25mm pitch. I hope they get it right.

 

[John S]

The pitch on the two fittings looked different to me, but I thought it must just be the photo as it is so easy to check the thread type. It just shows that it always pays to check the obvious.

 

[s class]

John the two fittings in the picture - the original sample from the red car, and the first copy are the same, and both work fine in the red car's valve. What I hadn't realised is that the blue car's valve requires a different pitch fitting to the red car.

 

[WGB]

It's only a few dollars worth of embarassment - nothing like a few thousand dollars worth of embarrassment and you now have a spare for the other car.

Bill

 

[s class]

Well I got another fitting made up, same as before, just now with a 1mm thread pitch instead of the previous 1,25mm. It looks great, but no pics because my wife's off overseas with the camera and my phone camera just doesn't have the resolution to photograph small items.

Believe it or not, this one was cheaper than the first - R42, or about $6.