B 26 backhoe running slower and slower

Tractor Seabee · Feb 26, 2013

Gary,

If you are going to work on your tractor yourself (I highly reccomend) the shop manual is a must have. Best $80 I have spent, has saved me thousands. Up here shop labor is $125/hr and I have been disappointed by their attitude, slow service, and prices. Its over 50 Miles to the good dealer shop. On my BX 25 the relief valve is on the rear of the trans case, easy to get to and no it won't spray you when you unscrew the cap to get at the spring. Springs can be iffy, and they break for no reason. May well be your problem. I just raised my pressure to 2000#, huge differance in performance. The little shims are cheap even at the dealer. Less than $1 for what I did in 10 minutes. Yes I have a gauge, the Surplus Center one, a steel tee and two QDs (M & F). The QDs (they are Parker) I got at the local Hyd Shop) as the SC ones do not match. Less than $40.

Ron

Ron

Gary Fowler · Mar 1, 2013

My 3000 PSI gauge came into and I hooked it up, got 2200 PSI at idle. Reving up to 2000 rpm didn't raise the pressure any, still steady at 2200. Now to find out what the pressure should be.
EDIT: Just read the manual for both backhoe and tractor and only pressure mentioned is max pressure on the loader which is 2402 PSI. Therefore it looks like my pressures are below the max but still should be good. I'm not going to try to shim up to get the additional 200 PSI. The flow may be slowing down for some reason, maybe a early fluid change(400 hour required, but only got about 220) to SUDT2 will help.
Maybe the pressure has reduced somewhat since I don't know what it was originally set at, it could have been set higher than recommended also. I think I will just live with it like it is for now, if something else requires repair at a shop, I will have them check the flow and set the pressure to max.
The only thing I haven't been able to check is that screen going into the reservoir that Carl told me his B21 had, but I don't know if the B26 has this as it doesn't look the same. Got to go to Kubota dealer for an air filter and motor oil filter so I can ask them. MAYBE they have a B26 maintenance manual.

Carl Bert · Mar 1, 2013

Gary Fowler said:
My 3000 PSI gauge came into and I hooked it up, got 2200 PSI at idle. Reving up to 2000 rpm didn't raise the pressure any, still steady at 2200. Now to find out what the pressure should be.

If you can't find someone with a shop manual to give you the correct specs, just tell me where to get a gauge (I need one anyway), I'd be happy to do pressure tests along with you and tell you what readings I get. I would need specific directions though, I'm not too knowledgable when it comes to hydraulics. Although there is always the possibility that my tractor also isn't pumping at full potential, but I doubt that. Ok let me know if I can help.

Gary Fowler · Mar 1, 2013

J_J said:
A short hose, this 3000 psi hyd gage, and a QD to match your tractor, or a gage screwed into the QD.. About $30.

Surplus Center - 3000 PSI 2.5" LF LM GAUGE

This is where I got mine thanks to JJ. It took about 4 days from time I ordered it. The gauge was only $16 but shipping and tax boosts it up to just shy of $30.
At least now I know what the pressure is but maybe not what it was when I got it.
The way I checked the pressure (which may or may not be the right way), was I took off the stabilizer hose connection which happened to be exact fit for the gauge, tightened it up, cranked up the tractor at idle and hit the stabilizer control lever slowly , the gauge slowly came up to 2200 but went back to zero when I released the lever which to me seemed to mean that the stabilizer valve has some leak by. I next revved the engine to 2000 and did another check, same pressure. Removed the gauge, hooked the hose back on the stabilizer and cycled it a couple of time to remove the air.
The reason I did it this way was first of all I didn't need to make a trip to get any QA connections and second, in order to get to the supply line, I would have had to disconnect the back hoe which I really didn't want to do.

Carl Bert · Mar 1, 2013

Gary Fowler said:
This is where I got mine thanks to JJ. It took about 4 days from time I ordered it. The gauge was only $16 but shipping and tax boosts it up to just shy of $30.
At least now I know what the pressure is but maybe not what it was when I got it.
The way I checked the pressure (which may or may not be the right way), was I took off the stabilizer hose connection which happened to be exact fit for the gauge, tightened it up, cranked up the tractor at idle and hit the stabilizer control lever slowly , the gauge slowly came up to 2200 but went back to zero when I released the lever which to me seemed to mean that the stabilizer valve has some leak by. I next revved the engine to 2000 and did another check, same pressure. Removed the gauge, hooked the hose back on the stabilizer and cycled it a couple of time to remove the air.

Correct me if I'm wrong, but the way I understand it is, the hydraulic system is in a continuous loop, so doesn't this gauge need to have a "T" on it with a male and female end, so it can be connected within the loop? So my question is, do I need to order a "T" connector along with the gauge?

woody · Mar 1, 2013

Gary, glad you got you a gauge from what I understand Kubota sets the pressure at the low end of the scale. When I raised mine it was only about 250 psi and I could tell a real difference. But what I did not do was to make sure the oil was hot and I can tell a difference now when I run it along time. Good luck

Coyote machine · Mar 1, 2013

Gary Fowler said:
My 3000 PSI gauge came into and I hooked it up, got 2200 PSI at idle. Reving up to 2000 rpm didn't raise the pressure any, still steady at 2200. Now to find out what the pressure should be.
EDIT: Just read the manual for both backhoe and tractor and only pressure mentioned is max pressure on the loader which is 2402 PSI. Therefore it looks like my pressures are below the max but still should be good. I'm not going to try to shim up to get the additional 200 PSI. The flow may be slowing down for some reason, maybe a early fluid change(400 hour required, but only got about 220) to SUDT2 will help.
Maybe the pressure has reduced somewhat since I don't know what it was originally set at, it could have been set higher than recommended also. I think I will just live with it like it is for now, if something else requires repair at a shop, I will have them check the flow and set the pressure to max.
The only thing I haven't been able to check is that screen going into the reservoir that Carl told me his B21 had, but I don't know if the B26 has this as it doesn't look the same. Got to go to Kubota dealer for an air filter and motor oil filter so I can ask them. MAYBE they have a B26 maintenance manual.

FWIW, Here's a link I found to an older thread talking about shimming for max or over max psi of the relief valve- (I don't know Kubotas very well so it may be an earlier model or not even your model, but if it helps....) http://www.tractorbynet.com/forums/customization/134652-bx-christmas-present.html hope it sheds some light. I just did a search on Google for bx PRV valve max pressure, etc.

Gary Fowler · Mar 2, 2013

sylwoody said:
Gary, glad you got you a gauge from what I understand Kubota sets the pressure at the low end of the scale. When I raised mine it was only about 250 psi and I could tell a real difference. But what I did not do was to make sure the oil was hot and I can tell a difference now when I run it along time. Good luck

So, does the oil pressure drop considerably when it gets hot like the oil pressure on a car? I didn't think of that and the oil was 40F which was ambient temp when I checked it. I just started it up and within seconds checked the pressure at idle which is 1100-1200 RPM on this TLB.
Has anyone checked their pressures cold then again when hot and noted any difference?

Tractor Seabee · Mar 2, 2013

Carl raised the important point. You are measuring dead end pressure not operating pressure. You need a tee and QCs to insert in either the pressure or the PB line to/from the BH. That way you can see any changes when operating cylinders (important to trouble shooting your problem). The gauge will not interfere in operation that way also. That is the true operating pressure. SC does not have the Parker QC Kubota uses. Get the number off yours and go to your hyd store for a steel tee and the QCs. Not familiar w/the BX 26 but my BX 25 factory spec is 1778-1849 psi at 104-122 degrees F and max RPM. I have mine at 2000 now and it made a world of difference. See my eaerlier post.

Ron

Gary Fowler · Mar 2, 2013

Tractor Seabee said:
Carl raised the important point. You are measuring dead end pressure not operating pressure. You need a tee and QCs to insert in either the pressure or the PB line to/from the BH. That way you can see any changes when operating cylinders (important to trouble shooting your problem). The gauge will not interfere in operation that way also. That is the true operating pressure. SC does not have the Parker QC Kubota uses. Get the number off yours and go to your hyd store for a steel tee and the QCs. Not familiar w/the BX 26 but my BX 25 factory spec is 1778-1849 psi at 104-122 degrees F and max RPM. I have mine at 2000 now and it made a world of difference. See my eaerlier post.

Ron

There is just a small problem with that in that with the hoe attached, you cant get to the couplings, you have to unhook the back hoe, drive forward a foot or more to get to the hoses so I couldn't just stick one inline and see what was happening. The tractor has no other hydraulic outlets on it. I suppose I could unhook the hoe, then put the gauge in between the lines (you unhook from the hoe and loop the supply to the backhoe back into the return. I don't think I would get much pressure showing in the loop as it would just be circulating to an open end so I wouldn't think it would show me any pressure above the resistance. I watched a video of someone checking the flow by doing the same thing, except they had a needle valve to gradually shut down the flow till it dead headed to check the max pressure before the relief valve opened. Flow seems to be based on no load conditions, as the pressure builds flow decreased till 0 at max pressure and dead head. That is what I was concerned with was that the relief valve was set too low. NOW it would be nice to have a flow meter and verify the flow.
Anyone know where to get one of those?