Empty your hydraulic oil tank, rinse it with diesel oil, clean and dry it.
Do the same for your hydraulic hose, pipe, valve group and cylinders. Use air in case of requirement.
Disassemble the safety valve of your system; check spring tension, bolt and poppet and reassemble. Release the spring tension and return it to the neutral position.
Replace the filters on the hydraulic system with new ones.
Make sure that the coupling (connecting gear) on the engine or transmission to be installed is not defective or hollow.
Connect the suction hose and pipe by filling with oil.
Make sure that the suction hoses and pipes are not brust, punctured or shrunk.
Fill the hydraulic oil tank with clean oil.
Operate your machine at idle speed for 10-15 minutes with all control valves in the neutral position. If there is no abnormal sound after the above operations; adjust the safety valves that you have previously set with the pressure recommended by the manufacturer (use pressure gauge).
Make sure that the hydraulic oil temperature does not rise above 80 ° C.