hey guys my boss has a 428 series 2 1990yr backhoe and it has a problem with the hydraulics, the hydraulic pump wont pressurize unless you move a backhoe boom/stick lever and as soon as you release the boom/stick lever it depressurizes? ie. power steering is nonfunctional, all hydraulics are painfully slow until you move the boom/stick lever then it works like new (hyd pump has been checked and its perfect and runs the correct charge pressure and working pressure) I have also heard the pump is always pressurized as long as the motor is running? has anyone dealt with this issue before or got any ideas???:beatsme:beatsme
anybody? please
I would be looking for a relief valve that sticks open in the loader circuit. If it builds pressure for the hoe it may be they have a priority valve and it kicks it back when the hoe is used.
assume it get's worse with hot oil? probably works ok when stone cold.... that's a secondary ball resolver seal leaking There's a series of shuttle valves throughout your DCV network called "ball resolvers". There is a step-by-step diagnostic procedure in the Cat manual for your machine that will help you figure which one has a leaking seal. not sure it's a DIY job, but there's something to discuss with the pros if you call someone out.