Kubota RTV 900 transmission problem - hardley moves in gear!
- Thread starter PACKASAURAS
- Start date
It was like new, the acceleration was fast and smooth. Low, medium, and high gear function as I expect. It has been 3 years and still runs good.
Hi All,
I'm new here, sorry to bring up an old thread but I've found the information in here quite helpful.
I've got an RTV900, got it about 5 years ago with approx 4000 hours on it.
We use it now and again, perhaps once or twice a month, or sometimes it just sits in the shed for a couple of months. I serviced it not long after we got it and the date written on the filters was 10 years old so it doesn't seem like it's been serviced a lot.
I got some new filters / transmission oil and serviced it, as it wasn't great going uphill. This made a bit of an improvement but it's still wasn't great. It's probably done around 100 hours since then.
The brakes don't work, the front left pack is missing and the mater cylinder was missing. I've just bought the stuff to hopefully sort this as well.
(just in case someone thinks the brakes could be sticking on).
I've pulled the tipping bed off, as it was pretty rotten. So while I'm rebuilding that and thought I'd try and figure out why it's so slow going uphill especially with a load on it. I'd say around walking speed with your foot to the floor, and I would think it should go faster than that.
It's like half revs or full revs makes no difference, it just goes pretty much the same speed uphill.
It doesn't seem too bad on the flat and goes quite fast once it gets going. It just seems very slow going up hills, although it does still get there eventually, just very slowly.
So I just thought that must be the way that Kubotas are, as I've not driven one prior to this, but from reading some posts it seems that other people have had similar issues.
I decided to pull the transmission apart and check the 3 brass plates which were quite worn and had a lip on them which you could feel with your fingernail. I ordered 3 new plates and fitted them today and gave it a test up the driveway (two of us in it, no bed on the back), and it seems to be pretty much exactly the same. So the new plates haven't made any improvement.
While I was in there I checked the pistons and springs on the pumps and they all seem ok and not badly worn or anything, no grooves in the sides.
I don't have any gauges to measure the pressures, and even if I did the pressure measurement ports seem seized solid.
I did try to remove them and one rounded off, and the other nearly snapped my allen key socket (it would have if I'd put any more pressure on it) so I'm unable to test pressures even if I had the gauges.
It seems to have a bit more torque in reverse then in L, not sure if that's helpful info.
If I put the handbrake on full, and put it in L and rev it, it will rev. It does load the engine a bit, but doesn't stall or anything.
I noticed that someone had an issue with the inner swash plate which had a pin broken / elongated and I'm wondering if this one could be the same?
I'm not sure how to check that, can it be checked by removing the top part of the transmission where the actuator for the throttle goes.
The back of the exhaust is missing so it's not the spark arrester.
I'm just wondering what I should look at next?
Thanks in advance
Mick
I'm new here, sorry to bring up an old thread but I've found the information in here quite helpful.
I've got an RTV900, got it about 5 years ago with approx 4000 hours on it.
We use it now and again, perhaps once or twice a month, or sometimes it just sits in the shed for a couple of months. I serviced it not long after we got it and the date written on the filters was 10 years old so it doesn't seem like it's been serviced a lot.
I got some new filters / transmission oil and serviced it, as it wasn't great going uphill. This made a bit of an improvement but it's still wasn't great. It's probably done around 100 hours since then.
The brakes don't work, the front left pack is missing and the mater cylinder was missing. I've just bought the stuff to hopefully sort this as well.
(just in case someone thinks the brakes could be sticking on).
I've pulled the tipping bed off, as it was pretty rotten. So while I'm rebuilding that and thought I'd try and figure out why it's so slow going uphill especially with a load on it. I'd say around walking speed with your foot to the floor, and I would think it should go faster than that.
It's like half revs or full revs makes no difference, it just goes pretty much the same speed uphill.
It doesn't seem too bad on the flat and goes quite fast once it gets going. It just seems very slow going up hills, although it does still get there eventually, just very slowly.
So I just thought that must be the way that Kubotas are, as I've not driven one prior to this, but from reading some posts it seems that other people have had similar issues.
I decided to pull the transmission apart and check the 3 brass plates which were quite worn and had a lip on them which you could feel with your fingernail. I ordered 3 new plates and fitted them today and gave it a test up the driveway (two of us in it, no bed on the back), and it seems to be pretty much exactly the same. So the new plates haven't made any improvement.
While I was in there I checked the pistons and springs on the pumps and they all seem ok and not badly worn or anything, no grooves in the sides.
I don't have any gauges to measure the pressures, and even if I did the pressure measurement ports seem seized solid.
I did try to remove them and one rounded off, and the other nearly snapped my allen key socket (it would have if I'd put any more pressure on it) so I'm unable to test pressures even if I had the gauges.
It seems to have a bit more torque in reverse then in L, not sure if that's helpful info.
If I put the handbrake on full, and put it in L and rev it, it will rev. It does load the engine a bit, but doesn't stall or anything.
I noticed that someone had an issue with the inner swash plate which had a pin broken / elongated and I'm wondering if this one could be the same?
I'm not sure how to check that, can it be checked by removing the top part of the transmission where the actuator for the throttle goes.
The back of the exhaust is missing so it's not the spark arrester.
I'm just wondering what I should look at next?
Thanks in advance
Mick
aurthuritis
Well-known member
So? Your 5 year old service has 100 hours on it?
Pretty much. It might be 150 hours? but I doubt it.
It sits in the shed most of the time, and only get's used now and then if I need to move logs or stone or something. We have another machine Avant 523 loader which gets (pretty much every day) and we've had that around the same length of time 5 years from new. That only has 224 hours on it.
Well I managed to heat the pressure test ports up with a blowtorch and hammer a Torx bit into them and remove them. (I'll order some new replacements plugs when I order some other parts I need).
I Ordered a set of gauges, which arrived today.
I'm not sure how this has even been driving as I seem to have 0 psi on the charge pump port. Even when revving it, nothing.
I disconnected the gauge and oil does slowly come out of the pipe going to the gauge (thought it might be blocked) but not squirting out or anything.
I did briefly try the high pressure side (while the wheels where off the ground as it's currently jacked up) and it showed around 800psi (although not a proper test as I didn't want to chance damaging anything).
I've got new Kubota filters and oil which I ordered the same time as the replacement pump plates but I've yet to fit them as wasn't sure if I need to pull this all apart again and do further investigations, and didn't want to waste all of the new oil I've just bought.
I've done a lot of reading over the last few days, to try and get my head round how the system works which I think I understand now.
One thing I've noticed is that you seem to have to rev it quite hard (to about 30%) before it does anything, but it's always been like that, so I thought that was normal? Still not sure if it is?
I did remove and check the high pressure relief valves and they seemed fine, and verified that the servo piston moves which it does when the engine is running, although I can only check this for a few seconds as the chamber fills with oil after a few seconds.
Not sure what to do next, was thinking of checking the hoses from the suction side, charge pump relief valve, or could it be the charge pump?
I Ordered a set of gauges, which arrived today.
I'm not sure how this has even been driving as I seem to have 0 psi on the charge pump port. Even when revving it, nothing.
I disconnected the gauge and oil does slowly come out of the pipe going to the gauge (thought it might be blocked) but not squirting out or anything.
I did briefly try the high pressure side (while the wheels where off the ground as it's currently jacked up) and it showed around 800psi (although not a proper test as I didn't want to chance damaging anything).
I've got new Kubota filters and oil which I ordered the same time as the replacement pump plates but I've yet to fit them as wasn't sure if I need to pull this all apart again and do further investigations, and didn't want to waste all of the new oil I've just bought.
I've done a lot of reading over the last few days, to try and get my head round how the system works which I think I understand now.
One thing I've noticed is that you seem to have to rev it quite hard (to about 30%) before it does anything, but it's always been like that, so I thought that was normal? Still not sure if it is?
I did remove and check the high pressure relief valves and they seemed fine, and verified that the servo piston moves which it does when the engine is running, although I can only check this for a few seconds as the chamber fills with oil after a few seconds.
Not sure what to do next, was thinking of checking the hoses from the suction side, charge pump relief valve, or could it be the charge pump?
aurthuritis
Well-known member
If the charge pressure is low nothing will work right.
Yes, I know. What is the likely cause / possible causes of low charge pressure?
I made a mistake with my initial post but couldn't edit it. I got mixed up with the mini digger we have which has the 4000 hours on it, the Kubota has 2231 currently and had around 2114 on it when we got it (it came with the farm).
It's still running about the same as when we first got it( when I changed the oil and filters (genuine and genuine fluid) from the dealer. So I don't think filters and oil are the problem, although I could still change them as I bought new ones, and new oil.
Are there seals in the charge pump?
I couldn't find much info / pictures on the internet of one in bits.
It seems to be around £280 for one.
It looks like it can be changed by removing the axle, and the right hand rear brake assembly, is this correct?
I'm just wondering what to check / change / how to proceed with this.
I made a mistake with my initial post but couldn't edit it. I got mixed up with the mini digger we have which has the 4000 hours on it, the Kubota has 2231 currently and had around 2114 on it when we got it (it came with the farm).
It's still running about the same as when we first got it( when I changed the oil and filters (genuine and genuine fluid) from the dealer. So I don't think filters and oil are the problem, although I could still change them as I bought new ones, and new oil.
Are there seals in the charge pump?
I couldn't find much info / pictures on the internet of one in bits.
It seems to be around £280 for one.
It looks like it can be changed by removing the axle, and the right hand rear brake assembly, is this correct?
I'm just wondering what to check / change / how to proceed with this.
aurthuritis
Well-known member
On the old rtv900 transmission there's a hose that serves the suction supply for the charge pump that was known to collapse internally and cause your issue. With the age of your machine i would replace the hoses first. And might be an idea to also replace the suction filter.
Thanks for the tip!
My RTV900 is also showing signs of slowing down with ~2200 hrs. Do you have a picture of this hose on a location in the service manual to find it?
Thanks
The two hoses are the one's here:
K7561-33450
K7561-33460
Unfortunately I don't think it's the problem on my machine. I checked them both and they were clear all the way through.
I've ordered two anyway.
After changing the 3 brass plates, I've changed the oil and filters, and it made no difference so it's all in bits again...
All of the main pumps / motors / pistons / swash plates show hardly any signs of wear.
Currently I've got the axle off, to access the charge pump.
I've got it removed although it shows minimal signs of wear (slight mark on the pump casing but can't feel with fingernail). I've ordered a new charge pump, and also the charge relief poppet and spring.
Awaiting them to arrive...
Attachments
Thanks for the prompt and useful information Mick. Looks like a complete teardown to solve the problem is underway. Hoping that you find the solution and keep us posted...thats a lot of work you have done so far!
aurthuritis
Well-known member
Thanks
Well, got it all back together at last, and not a huge amount of difference. New charge pump, genuine oil and filters, filter hoses, and all 3 brass plates changed so far (along with a driveshaft, oil seals, rear wheel bearing, brake master cylinder, and a front brake pack).
I bought a new speedometer for it as it was broken, so I can now see what speed it is doing. Forgot to mention that when we first got it, the date on the filters was 10 years old! So I don't think it had been serviced much by the previous owner / owners.
I get around 4-5mph at full revs uphill in L, 15mph in M on the flat, and around 15-16mph in H on the flat.
Charge pressure is around 70psi at idle, and around 90-105 psi when full revs (see pic).
The HST high pressure goes to around 3300psi when I have it in H with the handbrake on, and rev it (see pic), although I'm not sure how accurate these VEVOR gauges are...
I hooked up the gauge when I took it out to see what happens when it's being driven, and the HST pressure was around 1500psi when it was doing 4-5mph uphill. I stopped and put in H with the handbrake on again and revved it, and it went to around 3300psi again.
I also tried swapping the P1 P2 relief valves to see if it could be a faulty valve, as they seemed both the same spec from the manual, and it made no difference so I swapped them back.
I've attached a couple of photos (sorry about the quality as it's from video), as I also do YouTube videos on repairing stuff to help people repair things. I was asked to so some more mechanical type repairs on my channel, so started doing a video on the RTV900.
So I'm wondering now if it's a problem with the main pump, or the motor pump? although I didn't see anything obvious when I looked at them.
I've also tried adjusting the linkages and servo (neutral screw) but they seemed to be set about right.
Also how do you remove the motor pump? The main pressure pump the shaft seemed to come out quite easily. I tried tugging on the motor pump shaft but it seemed fairly solid, is there something you have to remove from inside the transmission? or does it just pull out with a bit more force?
Looks like I have to tear it apart again :'(
Thoughts welcome..
I bought a new speedometer for it as it was broken, so I can now see what speed it is doing. Forgot to mention that when we first got it, the date on the filters was 10 years old! So I don't think it had been serviced much by the previous owner / owners.
I get around 4-5mph at full revs uphill in L, 15mph in M on the flat, and around 15-16mph in H on the flat.
Charge pressure is around 70psi at idle, and around 90-105 psi when full revs (see pic).
The HST high pressure goes to around 3300psi when I have it in H with the handbrake on, and rev it (see pic), although I'm not sure how accurate these VEVOR gauges are...
I hooked up the gauge when I took it out to see what happens when it's being driven, and the HST pressure was around 1500psi when it was doing 4-5mph uphill. I stopped and put in H with the handbrake on again and revved it, and it went to around 3300psi again.
I also tried swapping the P1 P2 relief valves to see if it could be a faulty valve, as they seemed both the same spec from the manual, and it made no difference so I swapped them back.
I've attached a couple of photos (sorry about the quality as it's from video), as I also do YouTube videos on repairing stuff to help people repair things. I was asked to so some more mechanical type repairs on my channel, so started doing a video on the RTV900.
So I'm wondering now if it's a problem with the main pump, or the motor pump? although I didn't see anything obvious when I looked at them.
I've also tried adjusting the linkages and servo (neutral screw) but they seemed to be set about right.
Also how do you remove the motor pump? The main pressure pump the shaft seemed to come out quite easily. I tried tugging on the motor pump shaft but it seemed fairly solid, is there something you have to remove from inside the transmission? or does it just pull out with a bit more force?
Looks like I have to tear it apart again :'(
Thoughts welcome..
Attachments
aurthuritis
Well-known member
please remind me? What is the max no load governed speed of the engine? What is the max governed engine rpm with the transmission in high but stalled? Would be good to know the pressure at the same rpm?