Kubota RTV 900 transmission problem - hardley moves in gear!

[aurthuritis]

as collie stated in above post that plug is a drain and also a way to get more carbon out of the exhaust. on the newer models there isn't a screen but only a plug on the side that you remove and tap on the side of the muffler while revving the engine. i think you have an early adaptation of the newer model. can you get a product called SEA FOAM in your part of the world? if you can i would suggest adding some to the fuel and carefully^ _-atomize-_^ some into the intake to clean carbon from tops of pistons and valves.

 

[bordercollie]

It keeps sparks from setting the grass/ area on fire. I don't live in a fire danger zone so no longer have an arrestor on mine. If you do and keep it, you will just need to clean it often. That clogged thing would surely cause a decrease in performance. When my gas blower spark screen was clogged like that and I removed it, it was like a new machine. ( like being a youngster again. . Can't wait to hear how she preforms now.
When I removed the bottom plug on my long gone '05 RTV 900, I used penetrating fluid several days on the bottom plugthread edges and cleaned out the allen head indent with a pick to remove all the dirt. It you do try to remove it, be sure to get a snug fitting allen wrench and tap it in place to get all the grip you can . You may need to use a cheater pipe or something like a small end wrench to add to the allen wrench handle length.Just take you time and work it back and forth a bit so the fluid can work it's way up into the threads; - don't want a fire hazard if you're gonna be running so do what you think there , also don't want to twist off the allen wrench. If and when you remove and replace do use some of the anti seize stuff on the threads- mine came in a little dabber can. Good Luck ! collie

 

[Dvaepat4]

Hello all. The engine sounds a little different without the spark arrestor but the performance is the same. Ive checked strokes are maxed on throttle and transmission and they appear to be. Cant really work out what else I can try, however suspect I may need to open up the transmission box again and check inner swash plates etc? Does it get complicated beyond where I was earlier - if so I think I will get someone in to look at it. If not I will try doing it myself!

I can get diesel addative, which claims to clean pistons etc so may be worth a try. Recalling someones post from earlier suggesting I pressure test the tranny; is this easy to do, where can I buy a guage, what fitment do I need and where do I test it from? Sorry for all the questions. Thanks again. Dave

 

[aurthuritis]

if you want to continue working on this yourself and i highly recommend you do. i think you should get yourself some gauges that read in the pressure range of the HVT and some short hoses so you can test the pressures. you then can diagnose and adjust the relief valves and pumps to your liking. it could be your charge pump is weak or could be some debris in a relief valve"likely". disassembly of any of these is straight forward but you need the gauges to readjust after reassembly.

 

[Dvaepat4]

Thanks. Please see the attached photos (apologies for my lack of knowledge on these machines!); Is "A" the charge pump? Is pipe B a coolant hose to keep drive oil housing cool? Are Pipes D&E flow and return for drive and is this where I check charge pressure (suspect not as jubilee connections??). Which pipes and valves should I check to ensure clear of debris and free flowing and where are they?! Many thanks, Dave

 

[bordercollie]

I bow to Aurthuritis on the innards of the transmission. I've never been into that except when I replaced the rear ujoint s and pulled out the axles. I wish you the best though. bordercollie

 

[aurthuritis]

i am not very familiar with your year and model.i don't think that is the charge pump. the other lines you refer to are low pressure oil return lines and suction lines. i do believe your model has an oil cooler or warmer around the tan filter. the pressure ports will be small tapped plugs on the valve case. if you are going to tear into this you will need the specs of the info won't help. you should purchase a shop manual for your year and model. i think you will find many hours of enjoyable reading.

 

[Dvaepat4]

Hi there, I managed to find a WSM online - the images and diagrams are very interesting and useful, however I feel I may be going out of my depth! I think I will call someone in to do pressure checks and perhaps open up transmission box again. I have been looking at other posts and some were suggesting brakes may be stuck/sticking, however I have had it all jacked up and wheels are all spinning freely by hand. I think the suction filter was chocked so perhaps a backup of debris in pipes?, although i thought any residue would get could up in new filters (hopefully not too much). The engine seems to rev well enough and appears quite perky, however there is a delay and have to depress the accelerator to around 1/3 down before movement happens. It's a 2005 RTV 900 with power steering (had a hard life on a fruit farm and it's underside was caked with thick heavy mud...almost like cement!!). Mostly cleaned off now. It's done around 3700hrs also. Thanks

 

[aurthuritis]

look in your shop manual and find the flow chart for the hydraulic system. find the flow from the tank into the charge pump and then out of the charge pump into the case. you should be able to identify where the oil enters and exits the filter. then go to your machine and from the filter trace the lines and valves and you should be able to find the diagnostic ports ,the pump etc.the gauges won't be cheap so the cost of equipping yourself to do the job might not be worth the cost when you can pay for someone with more experience to help.

 

[Dvaepat4]

Had local dealer out today and pump showed 100psi (sould be 300psi?). Opened HST up and inner two swash plates were mildly scored (just feel ridge and no more with nail). Outer swash pate appeared fine. Dealer not 100% sure if new swash plates would be absolute solution so suggesting new complete HST unit...awaiting prices for each option! Thanks

 

[aurthuritis]

probably the pumps are leaking internally. new swash plates would help but may not completely fix the problem. i think the swash plates are pretty cheap though. sometimes you can get a good salvage HVT from Ebay. not to long ago there was a fella who replaced his with a new one from Kubota and the cost wasn't much more than a used one.

 

[aurthuritis]

i have a few questions. what pressure did you check? charge pressure? hvt pressure? did the tech put a tachometer on the engine and check the pressure at what RPM? also you could just need to clean a bypass valve. 300 lbs sounds high for a charge pressure and really low for the hvt pressure. have you consulted the manual?

 

[Dvaepat4]

A little update; I decided to purchase genuine valve plate kit – K7571-91374 (includes 3 valve plates, two gaskets and a manual for installation). Cleaned everything down with WD40 and tried my hardest to keep it clean whilst installing…very tricky at times!! Extracted all 3 valve plates and installed new (existing inner valve plates had grooves in them which could be felt when running finger nail over it, outer one appeared sound). New gaskets installed, bolts and filter reinstated and all tightened up. I was a bit confused by the manual as it said “notch” to valve plate was to be installed against the block, however I installed valves plates to match those extracted with brass side facing out. Started it up this morning, checked HST oil levels and topped up. Started up again and tried drive….but no movement….arrrrg!!! I am concerned that the hidden valve plate could have dropped off when installing – is this likely to have happened….is there space for it to fall off or if it did surely I wouldn’t have been able to tighten up casings and surely an external leak would be occurring?? I could see one of the concealed plates on the back of shaft was present by looking through. I also recall the inner swash plate (located behind filter) having an upper notch/knuckle on it – has this perhaps been dislodged during the process and not engaging? If I open up again will I need to renew gaskets again?

I recall reading someone experiencing this situation and they took it to a dealer to be told nothing was wrong with it (appeared to sort itself out!!). Perhaps oil and suction filters are airlocked? Any suggestions would be appreciated. Many thanks, David

 

[aurthuritis]

did you use copious amounts of assembly grease? from reading previous posters experiences similar to yours i would suggest you need to prime the system. probably need to fill suction filter with oil a few times

 

[Dvaepat4]

Thanks aurthuritis, I only had universal grease to hand and did not want to contaminate the new oil...so I didn't use any. I was very careful and I am confident everything is seated...only result in no drive is making me query myself!! I will slacken off suction filter tonight and see if it contains oil, then prime and see what happens. Thanks

 

[Dvaepat4]

Another late shift!! Checked filters and both holding oil. Decided to open up again and discovered inner valve plate (blind one behind mounted filter, when assembled) must have slipped and locating pin had damaged valve plate....grr. Damage was outwith sweeping area so carefully flattened and reinstalled....this time using assembly grease....!!! Put on and off a few times to check it was going on and staying on and all appears well. Now all reassembled and topped up with oil. Will try out tomorrow morning and update. Unfortunately when reassembling i overtightened one of the two bolts holding the rear oil filter and it sheared....under pressure with this still hold or should i repair? Do i need to open up to get to it or is there a way of doing it in-situ? It cheered quite deep in, almost at joint face. In hindsight i should have bought new bolts when ordering kit as i guess these will become fatigued when tightening and loosening over time. Another thing i noticed was a hole in the top of the pump block between the two shafts...its not a clean hole,more of a knock out....is this supposed to be open? Thanks again, David

 

[aurthuritis]

if a fragment of that plate comes loose it is going to trash the pump.

 

[Dvaepat4]

It flattened quite well and clean. Do you recommend i get a new one? Guess i could renew bolts whilst in there again!! Thanks

 

[Dvaepat4]

Ive ordered another valve plate kit just to be sure and avoid any damage to pump. Will change gaskets etc too.....a bit of expense incurred due to my error but have learned from my mistake....also buying some propper assembly paste not just grease. Is it likely i could have caused damage further in due to this misaligned plate? With the machine jacked up and gears engaged should wheels turn or lock? Thanks again. David

 

[Dvaepat4]

Hello folks, I meant to ask; i have been draining hst oil every time i open up hst block, however manual says you do not need to - is this true?! Where does oil come into hst block? Trust bearings where the two shafts penetrate are sealed so that only leaves the hole at the top (previously referred to as a "knock out"? Any advise would be appreciated. Going to open up again today an prep for new valve plates arriving. Many thanks, David