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.