rtvx 900 from spain 3600 hour and 67000 km

tabike

New member
I've had an RTVX900 for 10 or 12 years; it has 67,000 km and about 3,600 hours, I'm saying that from memory. Most of the time I've used it for work, making a 6-kilometer commute, but when it's been working, I've perhaps treated it somewhat roughly, carrying 600 kg of cargo in the bed plus a trailer of about 2,000 kg, and driving at full speed. The first repair was replacing some bushings in the wheel hubs. After that, until last year, when it had 60,000 km, there were no more repairs. But last year, the floodgates opened. We started by changing the ball joints, then the drive arms, which I bought in the US because they're very expensive here. We also changed the fan belt, the thermostat, and the temperature sensor, which I broke inside its housing, causing a breakdown that cost me a new head gasket. I took the opportunity to adjust the valves and timing; The engine looked perfect. A week ago, I had a problem: the vehicle would move and then brake on its own. My first thought was a previous driveshaft repair, which led me to remove the overrun brake. I thought the steel balls hadn't been reinstalled correctly, but after reading several posts, I think the problem is with the HST (Head Stabilizer Link), as I have no boost. Tomorrow I'll start by checking all the valves, and if I don't find anything unusual, I'll work on the HST. I hope the problem isn't too serious; the parts are very expensive here, and we can't buy them directly from a US dealer. Sorry for the length of the post. I'll keep you updated.
 
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Here it's the problem.
 

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Will you please inform us as to how many oil services on the hst in it's lifetime? And what kind of oils used? Was there any other failed parts in the hst other than wear on the rotating valve? Thanks
 
Oil and filter changes have been performed approximately every 200 hours, and the hydraulic oil has been completely changed 2-3 times. The oil type used has been Kubota's top-of-the-line Super UDT. The failure involved two pistons in the hydraulic motor, caused by excessive wear on the bearing disc. As a result of metal shavings, there is wear on the pump's copper disc, as well as on the internal swashplate seat, all due to the metal shavings from the damaged pistons.
 
The pump was seized, with a metal shaving; all the pressure readings were 0. Where do you buy the parts? The replacement pistons for the engine have to be the complete assembly, and they're very expensive—1000€ more in Europe than in the US. Is there any way to repair just those two pistons?
 
The pump or rotating valve assembly as kubota call it is an assembly only....but there is a member of this group has in his opinion successfully replaced damaged plungers with parts from a used ebay purchase. The bores in his valve block were undamaged.
 
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