Backhoe Reduced power in backhoe unit

[Danadj]

It appears I have blown and o-ring or some other bypass spool because the backhoe is not as strong as it has been. It will not load up the engine when I put it in a bind like it should. The loader is still as strong as ever. Any ideas where to look first?

 

[Hooked_on_HP]

Model of tractor and backhoe would be a great help

 

[Danadj]

Sorry, thought my signature would explain that but maybe it doesn't show up-it's a Ford 555D 4x4 extendahoe w/ 4in1 bucket. The machine is in good shape and this is something that has recently come light while I had it rented out on a job.

 

[Jbrink64]

It appears I have blown and o-ring or some other bypass spool because the backhoe is not as strong as it has been. It will not load up the engine when I put it in a bind like it should. The loader is still as strong as ever. Any ideas where to look first?

The main relief valve is in the loader valve. Since the loader is fine, I would assume the relief is ok.

As for the BH, if only one function is affected, look into a linkage problem (valve won't move fully), or a cylinder issue (bad piston seal) or a circuit relief valve that's NG.

If all functions are weak, then one of the many valves in the outlet end cap has failed. That's the cap on the lefts side of the valve stack. It has an unloader valve, and a back pressure regulator valve. Probably the unloader has stuck open.

 

[Danadj]

All functions are affected including the outriggers so I'm going to the unloader valve you spoke of. Thanks and I'll let you know how it goes. BTW, I have a shop manual specific for an older backhoe (555) and I'll look to see how similar/different they may be in this regard like I've done numerous times before.

 

[Craig Clayton]

I use to work on fork lifts many years back. I now work as an electrician. Electricity and hydraulics work the same ( Am I nuts ) , no you can not see either flowing only the results. So you have to measure the flow or pressure. Back to hydraulics I would suggest that you install a pressure gauge 0-5000PSI on the supply to the spool valve Tee it in.
This will show how much pressure the pump is delivering. Low pressure means the pump is unloading or worn out.
If you then Tee a o-5000PSI gauge on the boom/stick/dipper it will show how much the pressure is when you load that part.
So far we have not needed an expensive flow meter to measure flow. Speed of the machine under a high pressure means you have pump gpm's. With a low pressure gauge 0-100 PSI I think you can check your return line to sump ( assume ) it goes there there should not be more than 30PSI back pressure.
Check the hydraulic filter for clean. Silly question enough oil and correct type.Is there 2 pumps in the system suction line sucking air?
Craig Clayton

 

[Jbrink64]

All functions are affected including the outriggers so I'm going to the unloader valve you spoke of. Thanks and I'll let you know how it goes. BTW, I have a shop manual specific for an older backhoe (555) and I'll look to see how similar/different they may be in this regard like I've done numerous times before.

The 555 is very different from the D series. You'd be better off with the correct manual. Good luck.

 

[Danadj]

I'll get a good manual when I run across one. In the mean time I do have access to pressure gauges and may well check the pressures but I am certain it's a valve stuck or something of that nature.