Backhoe Backhoe works a little.

[sharpvet03]

I have a 3 point backhoe that is pto pump driven. The back hoe works great for a while and slowly losses power until the unit will not lift the boom any longer. All the other controls will work but with very limited power. I can take the line from the pump and place it in a bucket and seems to be be flowing about 5 gallons per minute at idle with no air bubbles in it.
The brand is TMI and only has about 5 hours on it but is about year old. I contacted the manufacturer and the said it sounds like the presure regulator. The sent me another one and I installed it and it is acting the exact same. Could the control valve be sucking air? Any ideas of what to try?

 

[Diamondpilot]

How warm is the fluid getting? I once saw a Ford tractor that lost oil pressure when the oil got hot. Took many hours but they finally figured out it was a weak spring in the oil pressure regulator. When the oil got hot it heated the spring than allowed it to lessen the pressure on the regulator ball valve allowing it to lose pressure.

Could be sort of the same thing????

Chris

 

[sharpvet03]

It sometimes happens after just ten minutes of use. The control valve does get pretty warm though. I just put a new pressure regulator on it and it is acting the same.

 

[leonz]

If you are running the PTO pump at 540 rpm with the engine speed at the engine rpm rated to run the PTO at 540 RPM the pump it should be running properly.


If you have time:

1. remove the pump completely from both hoses and drain the oil out of the pump cavity into a clean bucket.

2. place the pump in a vise and grip it with the vice jaws lightly.

3. take a quantity of hydraulic oil and pour it in the inlet side of the pump.

4. if you have more than a pencil lead diameter of oil draining through the pump cavity the pump is bad.


I am sure thats not what you wanted to here but the indications are leading to this unless, you have a relief valve

sticking open from dirt or debris or dealing with a bad relief valve which is the second possibility.

.

leon