Kubota RTV-900 Transmission won't engage

[JoeBob394]

2006 (I think) RTV-900 with 1800 hours.
when shifting into forward or reverse and depressing the accelerator, the unit revs but does not move. It is sometimes helpful to go back to N, rev the engine, and put it back in gear, and it will usually move. If you rev the engine while in F or R it will eventually catch and go, sometimes barking the tires.
The problem has gotten worse over time. In addition to being hard to get moving, now the unit lopes or continually surges about every second or so as it goes along.
All farm work, no trails or other abuse.
The unit was at the dealer for this issue back in January and a complete hydraulic service was suggested. I did the service and there was no change. The dealer said there is something wrong inside the transmission and they dont know what it could be without opening it up. Basically, he let me know they were not too enthusiastic about pursuing it.
Any help or ideas would be appreciated as always.

 

[Lone eagle ranch]

I have the exact same problem with my rtv , it’s practically useless

 

[rodnok]

2006 (I think) RTV-900 with 1800 hours.
when shifting into forward or reverse and depressing the accelerator, the unit revs but does not move. It is sometimes helpful to go back to N, rev the engine, and put it back in gear, and it will usually move. If you rev the engine while in F or R it will eventually catch and go, sometimes barking the tires.
The problem has gotten worse over time. In addition to being hard to get moving, now the unit lopes or continually surges about every second or so as it goes along.
All farm work, no trails or other abuse.
The unit was at the dealer for this issue back in January and a complete hydraulic service was suggested. I did the service and there was no change. The dealer said there is something wrong inside the transmission and they dont know what it could be without opening it up. Basically, he let me know they were not too enthusiastic about pursuing it.
Any help or ideas would be appreciated as always.

Have you tried doing a fluid and filter change on the unit

 

[Notforhire]

Several years ago I replaced the HST relief valve in my RTV900 with a coast valve. Coast Valve Kit for Kubota RTV900, RTV1100, RTV1140
I wanted to eliminate the quick deceleration when you let off the throttle.

While messing around with this valve I noticed that if I decelerated then "hit the gas" I would get a (short) lag in the transmission as the pressure built up, then it would take off.

Just a guess, but I suspect your relief valve may be sticking. It looks like this



You may want to run this idea by Kubota. I'm not a mechanic.

BTW it only takes around 15 minutes to change this valve.

 

[Jimmy Joe]

I was wondering if the surging is caused by an air leak somewhere in the hydraulic system had a tractor that did that and eventually found a small crack in one of the steel hydraulic lines running from the hydraulic pump to the hydraulic oil resivoir. It was not easy to find but it would suck air which caused surging of the engine being put under load then released. Hope you figure it out.