NEED HELP PLEASE! KUBOTA RTV 900 BAD TRANNY ?

[westbrooklawn]

Keep the posts coming... just because you aren't getting a lot of replies doesn't mean we aren't interested and still reading! I have an RTV 900 that has been awesome, but If I have problems down the road your thread may be very valuable to me. Thanks!

 

[art]

I've seen them with more hours then yours and I do hope it is still something simple just not an easy thing to diagnosis.

We probably will see some more indepth in the future as far as repairs. The pressures are important.

We've had more issues with engines and it has been with mud causing over heating issues. Had one that the radiator was totally clogged, overfill was full of mud as well, pull the radiator cap off and mud there as well! Still was good after flushing!

 

[tallur4me]

I am interested in your post as to the discovery of the problem. I have a new 900 RTV and might have need for the information down the road. Mechanical problems are always interesting as I believe there is a logical conclusion to each of them. The problem is to discover what's causing the problem.
Keep us up to date on the discovery and solution.

J D

 

[JOHNTHOMAS]

Your thread has had 988 views. That indicates alot of people are interested in this thread but we don't have answers. Some people post here for answers and some post to help others. You can do both and keep posting. You've also rec'd some responses with ideas and suggestions and some even from Kubota dealers.
Someone suggested you take it to a dealer, I agree with that one. Now you've rec'd some more input as to a solution. Course someone already suggested that so I had saved my suggestion.

 

[Blackplague]

Well cool, I had no idea you guys were all watching... Ill dig in to it more.
Pressure was 120 on low side ( more than good). High is only 800-1000 cold... Very very very low... Should be 3000-3500 psi warm. It could mean a lot of things..
Im guessing i have a stuck valve.. But the brass plate on the front pump could be shot a just need to get into it more tonight.

 

[Blackplague]

Im going in deep... Ill take some pics of what i find.
These hydro units operate via a lift (charge) pump just like you cars engine.
It feeds 100psi oil to the main pump.
As you give it throttle the charge pump feeds oil through ports to the servo piston.
It moves back and forth respectly depending on how much pressure is applied and directs the pressure to eather the drain or angles the plate so the high pressure pump starts displacing fluid in the form of pressure. That pressure from the high pressure pump gos to the piston pump motor # 1 and gets things turning... Now when there is heavy throttle and heavy load theres a back up ( assist ) motor that has its swash plate rotated via pressure flow from the regulator valve witch in returns gives it a extra motor....
During normal use this pump is at stand by and just going along for rhe ride..

This is the basics of how this works.

This is a very simple process on paper and understanding. However there is appx 11 different things that can go wrong to stop any or all of this from working corectly..



If ANYONE would like a picture or a copy of any page of this manual feel free to post up and ill get it.

 

[Blackplague]

Bingo!!!

The high end pump brass wear plate is badly warped and worn. This is causing a very poor seal and allowing pressure to be lost, hints my low hi end pressure..
Ill be replacing all 3 brass plates as everything elese looks brand new with no visable wear at all.

 

[Blackplague]

Heres another shot at how warped it is..
One pic is of the pump plate on a glass table laying on its side.. its warped enough to slide a quarter under the sides of it with out touching the plate its self.
The pump and motors dont have very much pressure against these plates so they wont flatten out as you would think. if bent warped exc they just pump the fluid every where it goes with least resistance (not motors for sure)

I assume this has been a issue with this unit for a long time.. With out being able to direct fluid flow corectly im sure made the plate and pump cavitate witch caused hot spots as you see and warped it.

As you can see the motor plates have some wear also, though not bad ill still be replacing all three. There kinda pricy for what they are. 126.00. But thats ok..
Some units ive rebuilt didnt have plates but the pumps mated directly to the plate. If it gets scored or warped in any way it was a 1000.00 bucks and up... I do thank kubota for that one in the sense this is not your typical throw away unit.

I will have my parts tuesday so ill put it back together and i bet it works... There is no doubt that pump plate was 100% of the issue.

 

[JOHNTHOMAS]

drain or angles the plate so the high pressure pump starts displacing fluid in the form of pressure. That pressure from the high pressure pump gos to the piston pump motor # 1 and gets things turning... Now when there is heavy throttle and heavy load theres a back up ( assist ) motor that has its swash plate rotated via pressure flow from the regulator valve

Wow!!! I will never attempt to do any type repair like this but I'm interested in reading all this info as I'm sure many of us are. Now I will be thinking about all this going on and the action of my swash plate doing all of it's stuff when I press the accelerator pedal on my RTV1140 and it moves.:thumbsup::thumbsup:
Congratulations on your work and keep posting. Nothing better to do on a 20degree day than to read this and think how glad I am that it's not mine and that a man such as myself is conquering the working of a RTV transmission.

 

[milkman]

Glad you're posting this, and glad you're going to come out with a great machine for not a lot of money.