B26 Repairs

   / B26 Repairs #1  

SamWalton

Platinum Member
Joined
Feb 9, 2008
Messages
539
Location
Sallisaw Oklahoma
Tractor
Kubota B26 TBL
We have had our B26 for two years and have only 200 hours of use. We purchased it to prevent the need to contract out many of the tasks related to the development of our land and home build. We had problems with the loader cylinders leaking and a backhoe stabilizer bleeding (scored cylinder) off too quickly at 60 hours. The dealer repaired all quickly and I changed all fluids and filter at this time. Since our warranty only had a few more weeks I brought it in to have them check it out because I felt the performance was somewhat weaker.
We have had the backhoe off a few times and got air in the lines but I was told this should migrate out. I also noticed rear stabilizers would no longer lift the tractor at the lowest throttle position (1000RPMS). After using the backhoe for many hours I thought it was getting weaker and slower.
I addition, a few observation I have made were the four point backhoe mounting has gotten somewhat looser, The paint has chip off and because of this loss of material the backhoe has a slight nock when stress is applied during use.
My dealer's service technician called and said the pressure was good but the flow measured low. Later he told me he was measuring at the wrong location and the first flow meter was bad. After the second day he got the owner involved because of his lack of experience. I spoke with the owner and he said there was no problem with my tractor. During the service the technician installed new hydraulic connectors to the backhoe. He also replaced a leaky hydraulic line to one of the stabilizers and tightened a connection that was leaking since delivery. They did all this for a $120 or an hour and a half of service time. The owner said the brought a new B26 in to the shop and tested both tractors for stabilizers ability to lift at idle. This is the part that bothers me; they set my idle up to a higher position (maybe 1200RPMS) and said it matches the new B26. I am not sure what the low idle specification is? If anyone knows please let me know? I am not sure but I think it use to lift at 1000RPMS. I guess it's time to purchase the shop manual. Does anyone think they may have turned the idle up to avoid finding the problem? I was worried the hydraulic pump may have been damaged because of the medal shaving in the hydraulic fluid because of the previously scored cylinder. Anyway please provide some opinions. Thanks and have a merry Christmas and a happy New Year
 
   / B26 Repairs #2  
Merry Christmas Sam,

I can't answer to all your comments because I've never had a tractor like yours. I did own a little BX22 for a few years though, and did experience some of the things you mentioned. My backhoe also felt weaker, and slower at the end of my owning it. At first I put it down to being more experienced, but then I became convinced that it actually was weaker, and slower. The only thing that I could think of at the time was that I had done many jobs that I really needed a bigger tractor for, and I had maxed it out to the pressure relief valves more than I should have perhaps. My guess was that although the pressure seemed ok, and the fluid flow seemed OK, perhaps I had worn those relief valves, and they were opening earlier, or not completely closing............ OK, you hydraulics guys can stop laughing now! :D Anyway Sam, I do believe you have an issue, and I hope you keep us posted as you resolve it. By the way, I think my B2620 has the same engine as yours, and it idles below 1200 rpm........... about 1000 I think.
 
   / B26 Repairs #3  
To operate backhoe's properly you should nt be operating them at an idle. This will cause cavitation in the pumps or otherwise known as air bubbles which will score the pumps and reduce the performance levels.

I'd say that with the low hours that that probably hasn't happened yet although I'd change the way you are operating it.

The proper way should be with a minimum of 1/2 throttle to 3/4ths depending on the chore at hand.

What you might be seeing with everything is that it is just getting seated in. From the paint coming off the four point hoe attaching to the use of the stabilizers. With running equipment and a host of other things that I didn't really know how to use or how much something might do I have often found that once I got used to the machine, I still could use more!
 
   / B26 Repairs #4  
Merry Christmas Sam,
OK, you hydraulics guys can stop laughing now! :D

In my experience, hydraulic guys NEVER laugh. It comes from long days of needing to have X-Ray vision due to the lack of test points.

I am not a hydraulics guy. I do play one at work, though, with a inborn willingness to hand it off to anyone else who will utter a single word related to hydraulics. TAG! You're it!

Ultimate force applied by your cylinder has to do with PRESSURE. Ultimate speed of your cylinder has to do with FLOW. Sloppiness of connection points and attachments results in freedom that must be taken up in both directions, therefore some hydraulic work that once resulted in productive work may now be going for unproductive work such as repeatedly taking up slop in the linkages.

It is possible for a worn pump to make pressure without making it's rated flow, but in my experience in a factory running 24x7*, it will not do it for LONG.
Such a pump will continue to degrade, and ultimately fail to make rated pressure.

In hydraulics, I wind up touching the equipment in lots of places looking for heat. All hydraulic power that is not used for productive work produces heat, and if you find the heat, you have found the internal leak. A fixed displacement pump will produce its flow at pressure, or it will get hot.

Some Kubota's (perhaps all) make an early grab for hydraulic flow for the steering, and only after that demand is met will there be power available for other things. It is possible your power steering is demanding a bit more leakage flow than when new.

*This is not meant to add impact to my statements, rather, it implies that once the internal leakage gets out of hand, our factory pumps will skid down the road to ruin much more quickly than your tractor pump.
 
   / B26 Repairs
  • Thread Starter
#5  
To operate backhoe's properly you should nt be operating them at an idle. This will cause cavitation in the pumps or otherwise known as air bubbles which will score the pumps and reduce the performance levels.

I'd say that with the low hours that that probably hasn't happened yet although I'd change the way you are operating it.

The proper way should be with a minimum of 1/2 throttle to 3/4ths depending on the chore at hand.

What you might be seeing with everything is that it is just getting seated in. From the paint coming off the four point hoe attaching to the use of the stabilizers. With running equipment and a host of other things that I didn't really know how to use or how much something might do I have often found that once I got used to the machine, I still could use more!

I don't operated at idle, but Kubota claims the stabilizers can be deployed at idle and this was true but now the dealer bumped up the RPMs since my tractor would no longer lift at idle.
 
   / B26 Repairs #6  
I was just on my B2620, and the idle speed is 1000 rpm as I thought.
 
   / B26 Repairs #7  
Merry Christmas Sam,

Sam, since your stabiliziers lifted the tractor before, they should do so now! Either the cylinder has an internal leak or there is not enough pressure to the cylinder (ie, check the pressure relief valve). Another possibility is the control valve for that cylinder is bypassing fluid. With open circuit hydraulics the relief valve pressure means that pressure will be available through the system, unless there is a blockage or leakage.

When you hooked up the backhoe lines, did you introduce any dirt into the system?

I have the B26 Shop Manual, but so far have not found the engine rpm setting.

The B26 Shop Manual is Kubota 9Y121-00040, $61.42 from Messiks.

The engine section of the Shop Manual refers to Workshop Manual DIESEL ENGINE MECHANISM (Kubota # 9Y021-01874) which I was unaware of. I bought my B26TLB in July 2008 and purchased the shop and parts manuals at the same time.

If you get the shop manual, I would recommend the parts manuals as well.

Illustrated Parts List Manuals
Model B26 Tractor ----------- # 97898-23430
Model TL500 Front Loader - # 97898-31610
Model BT820 Backhoe ------ # 97898-31620

The Parts Manuals are often more useful as they show how things go together.

Good luck,
Barry
 
   / B26 Repairs
  • Thread Starter
#8  
Merry Christmas Sam,

Sam, since your stabiliziers lifted the tractor before, they should do so now! Either the cylinder has an internal leak or there is not enough pressure to the cylinder (ie, check the pressure relief valve). Another possibility is the control valve for that cylinder is bypassing fluid. With open circuit hydraulics the relief valve pressure means that pressure will be available through the system, unless there is a blockage or leakage.

When you hooked up the backhoe lines, did you introduce any dirt into the system?

I have the B26 Shop Manual, but so far have not found the engine rpm setting.

The B26 Shop Manual is Kubota 9Y121-00040, $61.42 from Messiks.

The engine section of the Shop Manual refers to Workshop Manual DIESEL ENGINE MECHANISM (Kubota # 9Y021-01874) which I was unaware of. I bought my B26TLB in July 2008 and purchased the shop and parts manuals at the same time.

If you get the shop manual, I would recommend the parts manuals as well.

Illustrated Parts List Manuals
Model B26 Tractor ----------- # 97898-23430
Model TL500 Front Loader - # 97898-31610
Model BT820 Backhoe ------ # 97898-31620

The Parts Manuals are often more useful as they show how things go together.

Good luck,
Barry

Barry,
I am sure My B26 backhoe stabilizers lifted the tractor at the lowest idle from purchase to an undetermined time. I am guessing it was 1000 RPS. Why would the dealer fail to find the problem and just turn the idle up to 1350? and install some parts with no charge? My warranty will be over on the December 31st and maybe they have some other motive like they may be required to cover the cost of something they did wrong. This is the second service the first was a warranty repair and this they claim that no problem was found. Maybe expensive pars are marginal and the Kubota pressure and flow specification is relaxed enough they can get away with saying this is no problem? Their mechanic had the wheel off and measured pressure in multiple places and had the valve bodies and cylinders apart.

I always take great care when reconnecting the hydraulic lines by spraying them with WD40 to remove all dirt and wipe with clean cloth and bleeding some hydraulic fluid by mating the connector a few times and wiping with clean cloth again before a final mating.

I am quoting the Kubota Brochure "Increased Stabilizer Power
We've increased the stabilizer lift capacity to give you greater control on any terrain. The improved capacity results in better balance, which reduces
unwanted settling. It also means more strength-rear tire lift is possible even while the tractor is idling.

If it is not too much trouble, I would ask you B26 owners to test for the rear tire lift at lowest throttle position and note the RPM. Please let me know the results? Thanks!

If the dealer has handled this wrong? What is my next move? Kubota doesn't have a technical support line or do they?

I have downloaded all the parts manuals but need to purchase the shop manual PDF. It sounds like the Idle may be in this other engine manual.
Thanks for all the help so far
Sam
 
   / B26 Repairs #9  
I've got a b2630, which I believe to be identical to the B26. Perhaps a different pump? That is beyond me, but in any case, with the bh75 hoe, stabilizers lift machine at idle which is about 750-800 rpms - no problem. I've got 90 hrs on my machine, about half of it is very heavy backhoe work - stumps, and very large rocks.
 
   / B26 Repairs #10  
Sam,
I'm going to make the following as simple as possible and I don't have any B26 manuals to refer to. The B26 Hydraulic Pump is a Gear Type Pump which is one of the most common and dependable pumps used on tractors and aircraft as well as anything else that needs to make liquid pressure. Normally the design of a Gear Type Pump is such that it produces more pressure (PSI) than required to allow for low RPM. The pressure is reduced to operating pressure by an adjustable relief valve and the flow is probably set by calibrated orifices subject to the operating pressure. Both can be accurately measured with quality gauges used properly. The PSI can be confirmed by plugging into a port of the system being tested but normally the flow can only be measured by an inline flow gauge.

I don't know how many hydraulic pumps are used on a B26 but from the online specs I know that the B26 Hydraulic Pump produces 11.2 GPM of which 7.0 GPM is for the loader/backhoe/3-point hitch, 4.2 GPM is for backhoe boom swing, 6.2GPM for power steering per the online specs. I want to say that there are at least two hydraulic pumps with one for the power steering. My L39 has 3 pumps. I also know that the B26 Hydraulic System Relief Valve is supposed to be set to 420.6 PSI which is a low pressure system. I've found that most dealers don't have the equipment or know-how to accurately measure hydraulic flow. In reading the B26 advertisements I read that the B26 Rear Stabilizers are supposed to lift the tractor at idle speed. If it did when new it still should unless the system pressure is adjusted too low or the internal O-ring seals of the Stabilizers are leaking internally which is usually the reason for a leak-down!

With over 50 years of working with hydraulic systems I find that most mechanics don't know how to properly prepare a Lip, Chevron, or Garlock Type Seal properly and that is why some owners have repeated leaks. I have never had a Lip, Chevron, or Garlock Type Seal leak before TBO (Time Before Overhaul) after I've replaced them and I've replaced probably thousands since the 50s.

I seriously doubt that your Hydraulic Gear Pump has been damaged by any shavings and gear pumps can usually last thousands of hours (If not made from powdered metal). Rarely will cavitation damage a gear type pump as there is usually enough residual fluid in the pump to lubricate the gears.

Ask your dealer for the exact readings of PSI and GPM and to show you the gauges he used to measure the pressure and flow. I don't think he measured the flow. Keep us informed.

Good luck,
Jim
 
 
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