L35 - no hydraulic power to backhoe

[Jelf]

I did something stupid and am now trying to make it unstupid.

I have owned an L35 for many years and have taken the backhoe on/off many times when I needed to do 3-point work. After I get the hoe physically unhooked from the tractor then here is my standard method:
1. Drive short distance forward
2. Raise stabilizers so the feet are just clear of the ground. This lowers the front part of the hoe.
3. Detach hydraulics from the hoe
4. Attach tractor-tractor hydraulics
5. Attach hoe-hoe hydraulics
6. Operate hydraulic lever for the main boom. This further lowers the front part of the hoe.

But for some unknown reason the last time I detached the hoe I only did steps 1, 3, 4 and 5. As I drove away and looked back I could see the front of the hoe up in the air resting on the stabilizers and realized I screwed up. But instead of going back and making things right, I did 3-point work for a couple of days.

When I finally went to hook the hoe up, the front part of the hoe is on the ground and I could not disconnect the hoe-hoe hydraulic fitting. Apparently pressure in the system prevented my doing so.

I lifted the front of the hoe with the tractor bucket and wiggled the handles for the stabilizers. That relieved sufficient pressure that I could unhook the hoe-hoe hydraulics and hook up the hydraulics to the tractor.

I made sure the hydraulic lever was set to “backhoe”. Started the tractor. The backhoe is getting zero hydraulic power and the pump is making a faint whine.

I am guessing there may be hydraulic pressure in the hoe somewhere that needs to be relieved.

But before I fumble around and make a bad situation worse, has anyone been in this predicament before and figured out how to get out of it?

 

[oldnslo]

My first thought if pump is whining is that you do not have the back hoe connections fully locked together. I would double check those quick disconnects

 

[Tomtint]

Crack one of the hose fittings loose and bleed off the pressure

 

[Carl_NH]

I do a similar process plugging the male to female BH connectors together when I remove the hoe then relive the pressure from the lines by moving the controls.

Once I forgot to put it in 3PT mode and yes, the pump whined indicating a dead head condition.

I would disconnect the fittings put it back to 3 PT mode, see if the 3PT lifts, then release the BH pressure, then reconnect the BH and see if that solves it.

Bottom line - the same as what the others have said, you have a connection issue it appears.

 

[Jelf]

Thanks for the suggestions.
I have double checked that I am firmly coupling the hoses together.

When the tractor hydraulic line is hooked back to itself and the control is in the 3-point setting, then all the hydraulics on the tractor work fine with no pump whine.

 

[oldnslo]

If works without hoe connected I would reconnect the hoe and watch the hoses to the hoe. Does neither, one or both of them stiffen and swell like under pressure?
If neither sounds like problem with quick disconnect on pressure line.

If pressure only would points towards some problem in the hoe valve stack

If both points towards problem with return line quick disconnect.

 

[rScotty]

If works without hoe connected I would reconnect the hoe and watch the hoses to the hoe. Does neither, one or both of them stiffen and swell like under pressure?
If neither sounds like problem with quick disconnect on pressure line.

If pressure only would points towards some problem in the hoe valve stack

If both points towards problem with return line quick disconnect.

Nice problem solving. I'm betting on the return line disconnect myself.

To be more rigorous, the OP can make up a pressure tester to go between the quick disconnects. Use a hydraulic T, a 5000 psi gauge, and thread couplers on each end of the T to match your own disconnects.
Amazon has some styles of gauge already made up and also hydraulic pressure release tools. Or order from SurplusCenter.com.

I've not had that specific problem with the M59, but often have to release pressure on hydraulic of every kind. Everyone does.
I use a piece of wood and slap it with a hammer method of releasing pressure myself. Plus a rag to trap the spray. I keep meaning to get more sophisticated.
rScotty

 

[Jelf]

Got a couple of ideas to try but rain has arrived in the Pacific NW so will wait for dry weather. I will report back but it might be a few days.

 

[Smokeydog]

If you had significant back pressure you couldn’t have connected the quick disconnects.

On the M59, still have intermittent loss of either the left swing or down boom. No pump strain and can hear fluid moving. Recent as a few weeks ago. I spend 80-90% in 3pt mode with no problems. Exercising the backhoe with other functions eventually the problem suddenly goes away. Only two out of fourteen functions has caused trouble usually after mounting. I suspect somehow the relief valves are temporarily stuck open either from debris or air bubble or some way causing back pressure on the return line? Clearance issues of the relief valve moving parts? Can’t cause it to happen and don’t know just what I do to make it to go away. Thankfully it’s just very intermittent and doesn’t last long. Maybe it needs to be used more.

B26 backhoe has two connections and no valves to change and never a problem.

M59 has three connections and two valves to change. The valves have linkages that disappear under the floor sheetmetal. Their adjustment might be an issue?

 

[rScotty]

There has been a lot of threads about quick disconnects holding pressure. Since its raining, there is no better time to read some old threads.

Spoiler Alert: The answer is always to release the pressure on the fitting and make the connection. Then normal circulation can take place.

But if the backhoe is sitting in a position so that gravity is putting pressure on a cylinder it will be much easier if that problem is taken care of first. Otherwise just as soon as the pressure is released the cylinder will move a little and the pressure problem will be right back.

 

[Smokeydog]

Hydraulic cylinders sitting without relieving pressure can relax and possibility pull air in thru multiple seal points. Water too. Both cause all kinds of symptoms and problems. Had a dipper hose bust on a full size backhoe. After replacing took awhile to work the air out.

 

[Jelf]

Solved! Backhoe is mounted on the tractor and tucked away in the barn. What a relief!

I did two things.

1. Taking care to be safe, I was able to release pressure from the male backhoe hose. Yes, there was some pressure there.

2. I lifted the front of the hoe with the tractor bucket and placed wooden blocks under the base of the boom and under the frame near the front. By fiddling with those blocks I was able to change the center of gravity such that I could operate the boom cylinder a bit in both directions without hooking up the hydraulics. As the cylinder moved, the front of the hoe would tilt back and forth.

I do not have an exact sequence of steps to describe since I went through several sequences of fiddling with the blocks, releasing any pressure, moving the boom cylinder, hooking the hydraulics to the tractor and seeing if it worked.

One time with the hydraulics hooked up the boom very slowly closed, but nothing else worked.

More fiddling and then one last test before giving up for the day. This time instead of trying to raise the stabilizers I reached for the control that emptied the bucket AND IT WORKED.

I then completed the process of hooking up the backhoe and life is good.

Thanks to everyone that took the time to comment.

 

[Smokeydog]

Great! love a happy ending!

 

[Smokeydog]

Glad you resolved your problem. Wish I could better understand what caused the problem.

Attachments like grapples can build up pressure stored off the machine. Reliving the pressure to reconnect may only involve a teaspoon of hydraulic fluid to be released. Larger, more complex equipment like a backhoe have more risk particularly if moving after disconnecting? While the seals are good at sealing liquid in, not so good at sealing air out especially at vacuum. Little air inleakage is then compressible causing problems when reconnected?

Depressurizing equipment before storing important. Wish I knew what causes the M59 backhoe to act up and how to prevent it. Little bit of air in the wrong place messing with the valving somehow? When removing the backhoe, de mount then turn the tractor off, operate all valves to completely depressure the system, disconnect the hydraulic lines, couple two hydraulic lines together for storage. Only piece of equipment to act up this particular way. Had three other detachable backhoes and one non-detachable hoe without these symptoms.

 

[Carl_NH]

Yes - good to see its' resolved without issue. I do the same as you Smokeydog - when removing the BH (it goes on a rolling dolly setup) I block up the front plate under the swing arm, raise the stablizers, lower the boom then turn off the tractor.

At that point relieve all the pressure, remove BH lines, connect together, then move the valves again to ensure there is no pressure in system.

 

[5030]

What I do to keep from mixing up hydraulic connections (because a couple of my hay tools require multiple hydraulic hook up's to the remotes) (have have 3 sets of connections plus flow control on both my Kubota's is, I color code not only the tractor female remotes, but the implement hookup's with colored zip ties. That way I get them correctly hooked up every time. You just match the colors. Easy Peasy.

 

[Smokeydog]

The M59 backhoe is unique is that it has two supply pump lines and one common return. Can connect the main supply to return when removed. Dedicated swing supply is a small line and disconnect size. Wonder if design is why sometimes some owners lose swing temporarily in one direction?

 

[Stonehaller]

On the M59, still have intermittent loss of either the left swing or down boom.

Check the joy stick linkage. It may not be fully stroking the valves in one direction causing the loss of function. There may be debris restricting linkage movement.

M59 has three connections and two valves to change. The valves have linkages that disappear under the floor sheetmetal. Their adjustment might be an issue?

The one valve dumps the swing pump to tank. If the valve did not close all the way you would have reduced or no swing function. The other routes the power beyond from the loader to the 3-point. The backhoe is connected to the power beyond. Blocking power beyond to 3-point sends the power beyond oil to the backhoe. If the valve is leaking you would have reduced or no function on boom, dipper, bucket and stabilizers. As that is not the condition you describe, the joy stick linkage is the likely suspect.

 

[Smokeydog]

Check the joy stick linkage. It may not be fully stroking the valves in one direction causing the loss of function. There may be debris restricting linkage movement.



The one valve dumps the swing pump to tank. If the valve did not close all the way you would have reduced or no swing function. The other routes the power beyond from the loader to the 3-point. The backhoe is connected to the power beyond. Blocking power beyond to 3-point sends the power beyond oil to the backhoe. If the valve is leaking you would have reduced or no function on boom, dipper, bucket and stabilizers. As that is not the condition you describe, the joy stick linkage is the likely suspect.

Thanks for the suggestion. Linkage is in good shape. No debris, corrosion or binding.

No bad noises and can feel or hear fluid flow.

Problem is very intermittent. Couple of minutes of moving it and other functions fixes the problem. Hasn’t yet been enough or long lasting of a problem to break into the hydraulic system…yet. Always wonder if it will fix itself next time. It might get me in a bind sometimes.

 

[dougtrr2]

Thanks for the suggestion. Linkage is in good shape. No debris, corrosion or binding.

No bad noises and can feel or hear fluid flow.

Problem is very intermittent. Couple of minutes of moving it and other functions fixes the problem. Hasn’t yet been enough or long lasting of a problem to break into the hydraulic system…yet. Always wonder if it will fix itself next time. It might get me in a bind sometimes.

No doubt in my mind. At some point murphy's law will raise its ugly head, and it will be at the most inopportune time.

Doug in SW IA