Kubota Mechanical Advice

[Pks]

I am looking for a mechanic familiar with repairing Kubota hydraulic transmissions.

Here's what I have:
My B2400HD hydraulic transmission began leaking badly during usage. It leaked up under the frame rail along side of the pump/motor housing (at the cast iron valve body). I can't determine visually any better location than that. The transmission does not show any symptoms of a mechanical failure other than it leaks oil (about 1 pint per hour during use).
I have removed all the hydraulic pipes and lever linkages in order to split the transmission from the center frame. When I removed the suction strainer, there were metal shavings and a broken o-ring (about 3/8" diameter). The o-ring felt brittle when I played with it.
Where could this o-ring have come from and could it be part of the cause that something has broken?
Thanks, Peter

 

[dfkrug]

How much shavings did you have in the suction screen? It may be a
normal amount, esp if the screen has never been cleaned.

As for the missing O-ring, that is a good bet as to the cause of your
leak. More likely from the implement pump circuit vs. the hydrostatic
transmission, IMO. I do not know your tractor, but I have seen O-rings
used for some kinds of hydraulic connections, like between valves and
the sump, and with manifolds like you use to connect a loader.

For HST plumbing, the lines I see are usually hardlines with compression
fittings, or banjo fittings. No O-rings.

Some tractors use lots of O-ring face-seal fittings for the implement
pump circuit, (e.g. Deeres), but I don't think your B does.

 

[Pks]

There wasn't much in the way of shavings on the screen...just more than at the 300 hr maint interval. The o-ring is what surprised me. Due to the configuration of The transmission motor and pump assembly is one big chunk. So the o-ring must have come from inside. There is a separate implement pump & circuit but iit hangs off the side of the engine. The hydro-trans and pump assembly is under the seat and attached to the rear axel housing.

I suspect the o-ring came from the piston pump or piston motor which drives the axles.

 

[dfkrug]

There is a separate implement pump & circuit but iit hangs off the side of the engine.

Any O-ring in the system could be washed downstream into the sump.
Check the implement pump's hardlines. If they have flanges, they use
O-rings. If you have a loader, there is a manifold that connects to
the main tractor casting, and it uses O-rings. FEL valves may use O-rings,
too, but I do not think that is your source since your FEL valve is mounted
to the loader mast.