Replacing umbrella/cup seals - Roostamaster DB

sundvl76 · May 22, 2016

I have the injection pump off of my 861D to replace the umbrella, or cup, seals. (Yes, followed the correct procedure for removal, lining up marks, etc.)

The shaft does not want to come out of the pump, and while I have a Roostamaster manual for it, there's no mention of how to remove it. Posts on this site all seem to imply that it will just pull out for seal replacement, but it seems like there'd be a danger of it falling out when the pump is pulled if that's the case.

Is there some type of retainer holding the shaft in place, or is there a trick to it?

Thanks!

Ultradog MN · May 22, 2016

I've never done it but watched a guy do it.
He clamped the tang on the end of the shaft
in a vice and just gave a pull on the pump.
It came right out.

Dieseltech · May 22, 2016

Drive shaft has an O ring that is just inside the pilot bushing end to hold the shaft in place. Shaft will come out harder due to that O ring. How does the pump governor work? If the ring inside is failing that will cause the seals to leak. Replacing the seals only on a pump that has governor retainer trouble won't do any good. Any unstable engine speed changes without moving the throttle are good signs the pump needs repair.

sundvl76 · May 22, 2016

(quoted from post at 02:30:20 05/23/16) Drive shaft has an O ring that is just inside the pilot bushing end to hold the shaft in place. Shaft will come out harder due to that O ring. How does the pump governor work? If the ring inside is failing that will cause the seals to leak. Replacing the seals only on a pump that has governor retainer trouble won't do any good. Any unstable engine speed changes without moving the throttle are good signs the pump needs repair.

DT, the seals are being replaced because I'm trying to resolve the problem of getting fuel in the crankcase. Tractor starts and runs perfectly otherwise.

Thanks for the info - I'll just pull a bit harder!

sundvl76 · May 22, 2016

(quoted from post at 00:08:24 05/23/16) I've never done it but watched a guy do it.
He clamped the tang on the end of the shaft
in a vice and just gave a pull on the pump.
It came right out.

Good idea - I'll give it a try.

Thanks!

Dieseltech · May 22, 2016

The return line across the top of the injectors can leak too. More fun to get at since they are under the valve cover..

sundvl76 · May 22, 2016

(quoted from post at 02:43:58 05/23/16) The return line across the top of the injectors can leak too. More fun to get at since they are under the valve cover..

Right, I know about that possibility and am going to attack it after the pump seals. Not sure [u:5b0ed81f27]when[/u:5b0ed81f27] it is leaking (run or parked) so I'll repair both.

Thanks.

Destroked 450 · May 22, 2016

Got to do the same thing to my 881, it's been setting for years and the umbrella seals have let all the fuel leak into the crank case. Tank was completely empty when we pulled it out of the old barn it had been setting in.
It's a common problem with these old pumps

Replacing umbrella/cup seals - Roostamaster DB

sundvl76

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Ultradog MN

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Dieseltech

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sundvl76

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sundvl76

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Dieseltech

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sundvl76

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Destroked 450

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