brianidaho
Silver Member
OK, thinking things through a little more and reading the description on your plumbing. IF your system was set up like mine, prior to adding the backhoe and fel, your hydro system should have unloaded (tied the pressure line to tank) with the 3-pt valve is in the neutral or down position. Pressure would build (Pressure to tank blocked) only when the 3-pt is being raised.
You indicated that you went from the pressure port on the hydro access block in to the FEL P-port, FEL T to Backhoe P, Backhoe T to what would be the 3-pt P. All return to tank would be through the 3-pt valve, correct?
OK, if I am on top of things, if the 3-pt valve does have a tandem center position (pressure to tank), which would unload the pump, there should be no pressure in your system, assuming all of your valves are the same center style. If you are ideling, with the 3-pt in the hold position can you hear your engine load slightly? If so, does it unload when the 3-point switch is held in the down (float) position? If so, you might want to run her at speed with the 3-pt valve in the down position for the 10 minutes or so and see if it stays cool then.
With the series plumbing, all of your valves have to tie the pressure port to tank with the valves in the center position, otherwise you don't have flow downstream. Since you can operate your downstream components, it sounds like the proper spools are in the fel and backhoe. (In industrial hydraulics, a closed center valve is common, to maintain pressure in the system). Does your 3-pt raise at it's normal speed? If it's slow, you could have a restriction upstream somewhere. You can often hear oil flow (sort of hissisg) through an obstruction, and you should be able to feel around and see where your plumbing first gets hot.
Lots of speculating here, my setup is plumbed in parallel, rather than series. Based on how quickly you are heating up, it is most likely that you are not unloading the pump (dumping pressure to tank) when not operating a valve. Biggest suspect based on everything you've said, is the 3-pt valve. Is it hotter than the fluid inlet line? Also, can you find the relief valve in your system? If so, can you hear fluid flow over it? By rights, the only time there should be flow over the relief valve is when a valve is actuated, with a cylinder at full extension/retraction.
Good luck.
Brian
You indicated that you went from the pressure port on the hydro access block in to the FEL P-port, FEL T to Backhoe P, Backhoe T to what would be the 3-pt P. All return to tank would be through the 3-pt valve, correct?
OK, if I am on top of things, if the 3-pt valve does have a tandem center position (pressure to tank), which would unload the pump, there should be no pressure in your system, assuming all of your valves are the same center style. If you are ideling, with the 3-pt in the hold position can you hear your engine load slightly? If so, does it unload when the 3-point switch is held in the down (float) position? If so, you might want to run her at speed with the 3-pt valve in the down position for the 10 minutes or so and see if it stays cool then.
With the series plumbing, all of your valves have to tie the pressure port to tank with the valves in the center position, otherwise you don't have flow downstream. Since you can operate your downstream components, it sounds like the proper spools are in the fel and backhoe. (In industrial hydraulics, a closed center valve is common, to maintain pressure in the system). Does your 3-pt raise at it's normal speed? If it's slow, you could have a restriction upstream somewhere. You can often hear oil flow (sort of hissisg) through an obstruction, and you should be able to feel around and see where your plumbing first gets hot.
Lots of speculating here, my setup is plumbed in parallel, rather than series. Based on how quickly you are heating up, it is most likely that you are not unloading the pump (dumping pressure to tank) when not operating a valve. Biggest suspect based on everything you've said, is the 3-pt valve. Is it hotter than the fluid inlet line? Also, can you find the relief valve in your system? If so, can you hear fluid flow over it? By rights, the only time there should be flow over the relief valve is when a valve is actuated, with a cylinder at full extension/retraction.
Good luck.
Brian
