Kubota RTV 900 transmission problem - hardley moves in gear!

no need to send me anything. just find the page were it describes how to check the pressures and follow the order. there will be a chart that shows step by step this allows you to check each component one at a time in a process of elimination until you find the culprit.and use the search engine on this site for transmission problems and google also and you will find plenty of pictures and discussion. but the wsm if your best freind

a word of caution___ if the engine isn't running proper rpm and torque then the transmission could be just fine. i would step by step eliminate ALL possibility. i would adjust the valves on the engine check the primary fuel pressure take out the air cleaner and run it to see if there is any restriction etc. as an example i have seen farmers spend thousands of dollars on injection pumps and turbo charger on their tractors when the problem was a restricted secondary air cleaner.
 
I have my wsm. It's got the information that you said I needed. Seems like someone has already been down this path of checking pressures, the plugs have exposed pipe thread tape hanging from them.
 

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Yup i agree. but in order to figure things out you still best check pressures. could be you just have a weak spring or dirty bypass valve somewhere. that would be an easy cheap fix and wouldn't require major disassembly either. and later if you need to take things apart the information will help you decide what parts to replace. you are doing great job.
 
be advised. this wu flu has my days work like trying to run through a cow lot in knee deep mud without loosing a shoe. my availability could vary.
 
I need a little help with the adapters on page G54 of the wsm. I included pictures of the plug I removed from the high forward side. It's close to 13mm measures 12.97mm. The plug fits into a 1/4 npt female, but a male 1/4 npt only gets 1.5 threads before serious lockup in the hst plate. I am aware of the taper difference. I'm guessing the plug is M13x1, but I don't know for sure.
 

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aurthuritis said:
probably metric thread. i am not sure. could be a proprietary kubota thread. did you order the kubota brand test adapter???
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Haha, those kits are over $2000. For that price I can buy a lathe and make the adapters myself. It looks almost like bspp threads. Npt for 1/4" has 18 threads per inch. BSPP has 19 tpi. Once I verify that it is BSPP or BSP, I will start selling adapters on eBay. I can't believe how much Kubota likes those kits.
 
dmatlock2 said:
Haha, those kits are over $2000. For that price I can buy a lathe and make the adapters myself. It looks almost like bspp threads. Npt for 1/4" has 18 threads per inch. BSPP has 19 tpi. Once I verify that it is BSPP or BSP, I will start selling adapters on eBay. I can't believe how much Kubota likes those kits.
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yup. i agree. just a small hurdle for some and a huge mountain for others. the only suggestion i have that might help is get a thread gauge. but once you have it figured out please share so others can make the jump. that is what this place is all about.:thewave:
 
major undertaking

BSP is the correct size. I had a local hydraulic shop make a hose with 1/4 BSP male to 1/4 female npt. I'm refusing to pay Kubota $2100 for a $30 hydraulic hose and gauge. Page 2-S6 of the WSM shows maximum throttle spec in high gear should be 3271-3840 psi. I am maxing out at 3000 psi. Exactly what I figured to begin with. The pressure is low. Pressure is also lagging behind the throttle by a second or two. It's seems to be struggling to get the 3000 psi. idle pressure is approximately 2000 psi. Possible part number 07916-50381 07916-50371 07916-50392 07916-62601 07916-52391 07916-52040 07916-53072 07916-52621 07916-50045 hopefully search engines can find this and Kubota can get the hint that you can be replaced.
 

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good job. what is your charge pressure? what rpm is the engine running at those pressure readings? what oil temp??? needs to be hot. getting some realistic info Good Job

just for clarification are the filters Kubota? is the oil Super UDT?
 
Good catch, temps are cold. Filters and oil are aftermarket. It had Kubota brand on it when I bought it, like I mentioned before someone has already been this far and they tried brand new filters. I am a betting man and am willing to put a wager on the udt oil and filters being the issue. My next step is warm up and recheck high pressure. I doubtful of any changes. I have run this rtv up to temp before and it doesn't change anything.
 
yep good info is priceless. and i think just for learning sake i would run it up to temp and take as many readings as i could and maybe even a good stall speed reading. then change the oil to Super UDT and kubota filters and repeat the readings. try and get that charge pressure reading before you change the oil. Thank You for taking the time to do this right.
 
So I disconnected the servo and manually moved the lever at idle and the engine did not stall. I will check charge pressure shortly. The engine rpm is unknown. I don't have a tach.
 
dmatlock2 said:
So I disconnected the servo and manually moved the lever at idle and the engine did not stall. I will check charge pressure shortly.
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by stall speed i meant to apply the brakes and tie it down so the wheels cant slip and run it up to full rpm. check pressure and rpm at stall. itis important to know pressure and rpm at same time. you may need to put some weight in the bed and use high gear to get the transmission to stall no wheel slip.
 
by stalling the transmission and getting the pressure and rpm readings we get an idea if the governor is calling for more fuel and not getting it. this could be a simple fuel adjustment. but we will get a better idea when we see the results. you have checked the no load max rpm correct? did you get 3600 rpm???
 
Stall was done to get my measurements for high pressure on port 2. That's a symptom of my problem, it doesn't like to go uphill and stalls on even a slight incline. Charge pressure is in spec at maximum rpm. At 44°C I get 65 psi when idle and 110psi at maximum.
 
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