RTV900 2004 (with newer transmission) low charge pressure, won't move.

goggles99

New member
Good afternoon everyone. I purchased this knowing that it didn't move in forward or reverse, and got no history of it's condition. I have been reading all the threads on here about this problem. Strangely this seems to have parts from different years (at least the Hydro plate has the relief valves that can hook to a dash knob and the brake control lever). I have replaced all transmission fluids and filters with Kubota SUDT and verified that the input shaft is turning, the axle spindles are fine, it is going into gear and adjusted the linkages per the WSM.

After measuring the pressures, (charge pressure at 5 - 30psi), I finally got up the gumption to crack the rear most part of the transmission and inspect everything. There is slight wear marks on the pump pistons, some dents on the front and back of one of the valve plates, and the assist motor swash plate has some scratches (see pictures). Overall not too bad. To my surprise, the charge pressure relief valve seems to be missing. I had an oil pan below this to catch excess oil when removing the plate it is usually embedded into. I checked the oil pan and all over the floor because I thought perhaps it had just fallen out. Could this missing part be the cause of the low charge pressure? I have ordered a new one along with new valve plates.

One other thing, in the first attached photo, there appears to be a sunken part of the case, but it almost looks like the back it broken out of it, is this just a drain?

Thank you all, this forum is so helpful to a newbie like me. I am pretty handy in general, but have not worked on anything diesel or hydrostatic before.
 

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Smilingreen

Active member
Sure looks like someone has cracked that apart before. I wonder if they had any idea what they were doing? I see lots of scoring and wear.
 
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aurthuritis

Well-known member
Site Supporter
You must have a charge relief valve. The brass plate is severely worn and would probably be a real deterrent to pressure. The plate with deep marks needs replaced. The rotating valves look ok. The swash and it's tilt bearings look ok.
 
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