Jj1479
Silver Member
Might be an issue with the relief valve. Or even the pump might be going out.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
B26 tlb hydraulic issues
- Thread starter mmargush
- Start date
- Views: 40825
CurtisC
Bronze Member
Don't mean to hijack the thread but I had what sounds like a similar problem on my B26TLB after 400 hr. service which included filter changeouts and new load of super UDT. See post:
http://www.tractorbynet.com/forums/kubota-owning-operating/348415-b-26-hydraulic-pump-noise-post4297282.html#post4297282
Since then have run or fully stroked all hydraulics with no improvement. Went to plow after the big snow (coldest start since the service) letting tractor warm up for a good 10-15 minutes and had the now common whine at start up. After plowing a minute or so the tractor forward progress slowed down to almost stop while holding speed control pedal in same position and with no change in engine RPM. Came off speed control pedal and let engine run a bit tried it again and the tractor started moving then struggled again, I shut down it and checked hyd. fluid which was about a quart low. I'm not sure where it went with no signs of external leakage but this was the first time I'd checked it in a while and since removing the Hoe for the grading blade. Topped it off and restarted, the speed control was better - as I continued to plow and fluid warmed up, whine subsided and everything ran fine.
I suspect the culprit is something from the service maintenance process since problems started pretty much right after. The discussion about gasket leaks on hydraulic oil filter (mounted on side of tank) caught my attention. Unfortunately it will be a month or so before I'm back to check it out. In the mean time here are my thoughts:
1) I most likely have an air leak at the hydraulic filter interface mounted on side of tank. Keep me straight, but this filter is downstream of the pump and sees negative pressures whereas the HST filter is upstream and sees only positive pressure.
2) The performance improvement over time is likely due to gasket expansion/sealing taking place at the filter interface as things warm up?
This would explain why the colder it gets the more pronounced the problems are at startup.
3) Air ingestion in the suction line would that also account for the increased whine.
4) I did use WIX filters but wouldn't think filter failure or partial failure other than at the gasket sealing interface would result in what I'm experiencing.
Thoughts from you guys that know hydraulics??
http://www.tractorbynet.com/forums/kubota-owning-operating/348415-b-26-hydraulic-pump-noise-post4297282.html#post4297282
Since then have run or fully stroked all hydraulics with no improvement. Went to plow after the big snow (coldest start since the service) letting tractor warm up for a good 10-15 minutes and had the now common whine at start up. After plowing a minute or so the tractor forward progress slowed down to almost stop while holding speed control pedal in same position and with no change in engine RPM. Came off speed control pedal and let engine run a bit tried it again and the tractor started moving then struggled again, I shut down it and checked hyd. fluid which was about a quart low. I'm not sure where it went with no signs of external leakage but this was the first time I'd checked it in a while and since removing the Hoe for the grading blade. Topped it off and restarted, the speed control was better - as I continued to plow and fluid warmed up, whine subsided and everything ran fine.
I suspect the culprit is something from the service maintenance process since problems started pretty much right after. The discussion about gasket leaks on hydraulic oil filter (mounted on side of tank) caught my attention. Unfortunately it will be a month or so before I'm back to check it out. In the mean time here are my thoughts:
1) I most likely have an air leak at the hydraulic filter interface mounted on side of tank. Keep me straight, but this filter is downstream of the pump and sees negative pressures whereas the HST filter is upstream and sees only positive pressure.
2) The performance improvement over time is likely due to gasket expansion/sealing taking place at the filter interface as things warm up?
This would explain why the colder it gets the more pronounced the problems are at startup.
3) Air ingestion in the suction line would that also account for the increased whine.
4) I did use WIX filters but wouldn't think filter failure or partial failure other than at the gasket sealing interface would result in what I'm experiencing.
Thoughts from you guys that know hydraulics??
CurtisC
Bronze Member
Don't mean to hijack the thread but I had what sounds like a similar problem on my B26TLB after 400 hr. service which included filter changeouts and new load of super UDT. See post:
http://www.tractorbynet.com/forums/kubota-owning-operating/348415-b-26-hydraulic-pump-noise-post4297282.html#post4297282
Since then I have run or fully stroked all hydraulics with no improvement. Went to plow after the big snow (coldest start since the service) letting tractor warm up for a good 10-15 minutes and had the now common whine at start up. After plowing a minute or so the tractor forward progress slowed down to almost stop while holding speed control pedal in same position and with no change in engine RPM. Came off speed control pedal and let engine run a bit tried it again and the tractor started moving then struggled again, I shut down it and checked hyd. fluid which was about a quart low. I'm not sure where it went with no signs of external leakage but this was the first time I'd checked it in a while and since removing the Hoe for the grading blade. Topped it off and restarted, the speed control was better - as I continued to plow and fluid warmed up, whine subsided and everything ran fine.
I suspect the culprit is something from the service maintenance process since problems started pretty much right after. The discussion about gasket leaks on hydraulic oil filter (mounted on side of tank) caught my attention. Unfortunately it will be a month or so before I'm back to check it out. In the mean time here are my thoughts:
1) I most likely have an air leak at the hydraulic filter interface mounted on side of tank. Keep me straight, but this filter is downstream of the pump and sees negative pressures whereas the HST filter is upstream and sees only positive pressure?
2) The performance improvement over time is likely due to gasket expansion/sealing taking place at the filter interface and/or as fluid warms up the pump creates less negative pressure to bring the oil up from the reservoir?
This would explain why the colder it gets the more pronounced the problems are at startup.
3) Air ingestion in the suction line would that also account for the increased whine from the pump.
4) I did use WIX filters but wouldn't think filter failure or partial failure other than at the gasket sealing interface would result in what I'm experiencing.
Thoughts from you guys that know hydraulics??
http://www.tractorbynet.com/forums/kubota-owning-operating/348415-b-26-hydraulic-pump-noise-post4297282.html#post4297282
Since then I have run or fully stroked all hydraulics with no improvement. Went to plow after the big snow (coldest start since the service) letting tractor warm up for a good 10-15 minutes and had the now common whine at start up. After plowing a minute or so the tractor forward progress slowed down to almost stop while holding speed control pedal in same position and with no change in engine RPM. Came off speed control pedal and let engine run a bit tried it again and the tractor started moving then struggled again, I shut down it and checked hyd. fluid which was about a quart low. I'm not sure where it went with no signs of external leakage but this was the first time I'd checked it in a while and since removing the Hoe for the grading blade. Topped it off and restarted, the speed control was better - as I continued to plow and fluid warmed up, whine subsided and everything ran fine.
I suspect the culprit is something from the service maintenance process since problems started pretty much right after. The discussion about gasket leaks on hydraulic oil filter (mounted on side of tank) caught my attention. Unfortunately it will be a month or so before I'm back to check it out. In the mean time here are my thoughts:
1) I most likely have an air leak at the hydraulic filter interface mounted on side of tank. Keep me straight, but this filter is downstream of the pump and sees negative pressures whereas the HST filter is upstream and sees only positive pressure?
2) The performance improvement over time is likely due to gasket expansion/sealing taking place at the filter interface and/or as fluid warms up the pump creates less negative pressure to bring the oil up from the reservoir?
This would explain why the colder it gets the more pronounced the problems are at startup.
3) Air ingestion in the suction line would that also account for the increased whine from the pump.
4) I did use WIX filters but wouldn't think filter failure or partial failure other than at the gasket sealing interface would result in what I'm experiencing.
Thoughts from you guys that know hydraulics??
dabadas
New member
I have a whine also. I can bleed off the air and everything works perfect. But, it can sit overnight and when I start it the next day the pump whines and I have air again. The steering will be hard to turn but after a little working back and forth the steering starts working and the HST works. But I have no hydraulics. No front loader no backhoe no 3 point hitch. Nothing works till I bleed the air off. It should not be losing its prime. I've taken the suction line off and the filter bracket and checked them. Changed filter, o-rings and the rubber elbow at the pump. It still loses its prime. Is there something else it could be? Short of buying a pump? THANKS
CurtisC
Bronze Member
dabadas,
In my internet travels this is what I came up with on hydraulic gear pumps: Whine or excessive noise is caused by either cavitation or aeration. Cavitation occurs when the pump is unable to draw oil creating a vacuum which then results in the oil that is present vaporizing. Aeration would come from air being introduced from the suction side. Both situations result in an implosion of the vapor bubbles as the gas is compressed creating a multitude of little shock waves that erode the pump chamber wall and wear plate. Both also result in extra noise or whine at the pump. I'm clearly no hydraulics expert but I'd expect a worn pump to have reduced output flow but not be the actual entry point for aeration (except where suction line connects to the body). Just curious, are you using Kubota filters and did the problem occur gradually over time or was it good one day bad the next? In my case I'm still suspecting the WIX filter I put in as either defective and causing too much flow restriction particularly with high viscosity (cold) oil or because I've got a bad seal since problems showed up after filter change. I've used WIX before and had good luck but I think the next one I put in will be a Kubota. FYI I thought this discussion on the merits of suction side filters in hydraulic systems interesting - Suction Filters in Modern Hydraulic Systems.
In my internet travels this is what I came up with on hydraulic gear pumps: Whine or excessive noise is caused by either cavitation or aeration. Cavitation occurs when the pump is unable to draw oil creating a vacuum which then results in the oil that is present vaporizing. Aeration would come from air being introduced from the suction side. Both situations result in an implosion of the vapor bubbles as the gas is compressed creating a multitude of little shock waves that erode the pump chamber wall and wear plate. Both also result in extra noise or whine at the pump. I'm clearly no hydraulics expert but I'd expect a worn pump to have reduced output flow but not be the actual entry point for aeration (except where suction line connects to the body). Just curious, are you using Kubota filters and did the problem occur gradually over time or was it good one day bad the next? In my case I'm still suspecting the WIX filter I put in as either defective and causing too much flow restriction particularly with high viscosity (cold) oil or because I've got a bad seal since problems showed up after filter change. I've used WIX before and had good luck but I think the next one I put in will be a Kubota. FYI I thought this discussion on the merits of suction side filters in hydraulic systems interesting - Suction Filters in Modern Hydraulic Systems.
dabadas
New member
OK Here is the back ground. I purchased this backhoe on 1-17-2016 used. It worked fine I loaded it on the trailer and drove the 7 hours home. waited till later that day to unload it. When I started it up nothing worked. Front loader, backhoe, 3 point hitch, steering or HST. I checked the fluid and added about a quart. finally got it working and the fluid foamed out the overflow tube from all the air (it looked milky( but it wasn't water in it. I drained the fluid and put on new HST and hydraulic filters. It had Kubota filters on it but I put Car Quest filters. (friend that works for Hertz says that's all they use). I have removed and inspected the metal suction line and the filter bracket. I also changed the o-rings and the rubber elbow where it attaches to the pump. I also took the pump off and tore it down and inspected it. after getting the air out everything works great. the pump has great pressure. After letting sit for 1 hour everything still works. But, After sitting all night the air is back. The steering and HST is not as bad it will start working rather quickly. But, the front loader and backhoe nothing full of air. I would replace the pump if I knew that would fix it. But I hate to take a 800 dollar gamble. I have no idea why its losing its prime.
dabadas
New member
Are you talking about the pressure tests?
100 td
Platinum Member
- Joined
- Aug 29, 2015
- Messages
- 525
- Location
- ɹǝpunuʍop
- Tractor
- Kubota B21TLB (B21, TL421, BT751) Toyota SDK4, T116 Bobcat
No (but pressure tests would be good), simply the sequence of events listed to ensure hydraulic circuit is minimal, all valves are in the correct place and not dead heading the pump, and there is no restriction to air flow back into oil reservoir to create a negative pressure at pump. Just the tests/checks listed
