Main relief valve (MRV) 25/929310 JCB 3CX/4CX, aftermarket

For the JCB 3CX and 4CX backhoe loaders: main relief valve (MRV) 25/929310, an aftermarket part.

Valves are made with very small clearances and are sensitive to dirty oil: particles scratch or jam the valve element and cause leakage across the seats. A valve failure is therefore often a sign of an oil cleanliness problem, and the hydraulic filter is checked when the valve is changed. Adjustable valves are set at the factory, and the setting may only be changed to the service data with a gauge. When fitting, clean old seal remains out of the cavity, oil the new O-rings with clean oil, start the valve by hand and tighten it to the specified torque. After fitting, test the function under load and check for leaks. The valve comes new and unused.

Specifications

Compatibility

According to sources, this is the main relief valve (MRV) of JCB 3CX, 4CX and 3DX backhoe loaders; sources give its setting as 3200 or 3300 psi. Other parts are in Hydraulic valves.

Fitting

After changing the valve, run the related function through its full stroke several times to bleed the circuit. Check the valve joint again after the first hours of work, since a slight leak can mean an O-ring has not seated properly.