Power steering pump O-ring

[dirkbalter]

Hello,
I am rebuilding / resealing my power steering pump and recognized that the rebuild kits do not include the o- ring for the pressure valve.
Does anyone know the actual dimensions and material? The only one I could find was from SLS but I don’t really want to have just  an o-ring shipped from Germany.
Thank you

[Pawel66]

Perhaps it is this one. $10 at MB.

[wwheeler]

You can find one locally but you have to know if it I metric or imperial inches. I think this is a Vickers pump and may very well use a inch O-ring. If you take the o ring off, you can measure the groove with calipers. From there you can determine which one you need.

As far as material, this is ATF and usually BUNA-N (Nitrile) is selected. Viton (FKM) is an upgrade and possibly the best choice. ATF is harder on material than motor oil and the system has elevated temps. All of which Viton excels at.

[MikeSimon]

Dirk: What part are you showing in your photo? That's not a valve.

[dirkbalter]

Hey Mike, is that not the pressure valve?

[dirkbalter]

Pawel, thank you for the part #, I couldn't find it on my online parts finder. I will check with the classic center here.

Wallace, it appears to be metric. The lip seal for the pump shaft has metric dimensions molded in. I am measuring the groove at 13mm and the housing at 17.8. The cross section of the old O-ring is approx. 2.6-2.8mm, hard to measure due to age.

In any case,
Thank you.

[MikeSimon]

Yes, Dirk. That's the combo pressure and flow control valve. I could not make sense of the part in the first picture.
The pump was manufactured by Vickers in Bad Homburg, Germany. It was based on an original US design, thus a lot of dimensions are SAE standard. However, some of the parts sourced locally were metric, of course. There is quite a mix of dimensions on these pumps. Hard to say what the O-ring was without looking at a drawing.

[dirkbalter]

Thanks Mike. My pump shaft has no feel-able play radial and only 0.3-0.4 in axial direction and I am not planning to change or replace the bushing. However, I also can not figure out how I would remove the shaft from the housing? Any input or possibly a section cut drawing of the assembly? I read somewhere it has to be tapped out towards the front? If memory serves me right, you are an expert on these?

 

[wwheeler]

Based on your dimensions, I think it is an imperial inch O-ring. Given the dimensions, that is a 2.4mm (.094") cavity cross section (steel, not O-ring). The actual O-ring width needs to be bigger to seal and more like 2.65mm (.104"). That seems to be pretty close to what your old O-ring measured. If so, that is a 3/32" inch size O-ring (#112). And the groove width should be slightly more than 1/8" (.140" or so). If that lines up, then that should be a good match.

See McMaster spec -  https://www.mcmaster.com/9464K25/ I would recommend Viton which is what this is. You won't find this at a hardware store and no telling what material they use for theirs.

[dirkbalter]

Thank you Wallace.
(You may not remember but I was a student in the class you gave at the Pagodafest)

[wwheeler]

Oh yes and thank you for reminding me. This info comes in handy once in a blue moon. Hopefully it helps.

[MikeSimon]

Thanks Mike. My pump shaft has no feel-able play radial and only 0.3-0.4 in axial direction and I am not planning to change or replace the bushing. However, I also can not figure out how I would remove the shaft from the housing? Any input or possibly a section cut drawing of the assembly? I read somewhere it has to be tapped out towards the front? If memory serves me right, you are an expert on these?

If memory serves me well, the shaft is held in place by a snapring. Let me search my records and see if I can come up with a cross section view.

[MikeSimon]

I think the rebuild kit includes the O-ring. I don't think you want to pay for a rotating group,however. The O-ring p/n was 000 997 74 45. And i am sure at one time, Vickers/MB supplied a "seal kit"

[Pawel66]

That would be the same part number that is on the part list.

[JPMOSE]

I don’t think that O-ring is included in the kit. I rebuilt the power steering pump on my 250SL in September 2017 and had to order it separately.  I obtained it fro the classic center.

[dirkbalter]

Thank you all for the help.
Dirk