What are these?

[tommyg 154]

I'm replacing the O-rings between the manifold and hydro pump on my D-180. I've got a NOS seal kit. In it are 7 O-rings. There are 3 larger backer rings and two matching O rings. I'm assuming the two larger O rings and associated backer rings belong to the high pressure ports. The two smaller O rings belong to the smaller low pressure ports. I don't believe these require the backer rings. I also have one metal bound O ring the size of the smaller O rings. My questions are... Why do I have one extra high pressure O ring and what the heck is that metal bound O ring for?

Edited May 29, 2015 by tommyg

[wheeledhorseman 579]

Having just reassembled the hydro system on my D-200 I can offer the following. At the pump end you need two smaller O-rings for the low pressure, two larger O-rings with backer rings for the high pressure.

Having separated the pump and motor from a tandem unit from a C series to use as replacements for my D, I'm pretty sure the kit you have can be used to mate a pump to motor in tandem configuration when you'd need the copper / metal bound washer (it seals one of the allen key bolts that holds the motor casing to the pump internally. The extra backup ring you have seals the faces of the pump and motor where that bolt passes through. You'd need the extra backup ring for the motor end - manifold connection on a D but the copper / metal bound washer is needed for direct pump - motor connection only.

I'm sure someone else will correct me if I'm wrong.

Andy

[tommyg 154]

That sounds like a fair answer. If I'm just replacing the pump end seals, it seems all I would need would be the two larger high pressure O rings, the two backer rings and the two smaller low pressure O rings. Sound right?

[wheeledhorseman 579]

That's what I used.