FLEX HOSE 1C4345 - Caterpillar

At operating temperature, the hydraulic oil is hot and under pressure. Hot oil can cause burns. To prevent possible personal injury, release the pressure in the implement hydraulic circuits (boom, stick, bucket, and swing), the travel circuits, and the hydraulic oil tank at the breather cap before any hydraulic lines or components are disconnected or removed. Remove the filler plug only when the engine is stopped and the filler plug is cool enough to touch.
1. Release the pressure in the hydraulic system as follows: a. Fully retract the stick cylinder rod.b. Adjust the position of the bucket so it will be flat on the ground when the boom is lowered.c. Lower the boom until the bucket is flat on the ground.d. Stop the engine.e. Place the engine start switch in the "ON" position without starting the engine.f. Move the control levers for the boom, stick, bucket and swing to all full stroke positions. This will release any pressure that might be present in the pilot system.g. Slowly move the travel pilot control pedal to "FORWARD" and "REVERSE" travel positions. This will release any pressure in the travel circuit.h. Slowly loosen and remove the pressure cap on the hydraulic tank to release the hydraulic pressure.i. Reinstall and tighten the pressure cap on the hydraulic tank.j. The pressure in the hydraulic system has been released and implement/travel lines and components can be removed. 2. Remove four hex head fasteners (2) and cover assembly (1) from under the radiator and hydraulic oil cooler. 3. Remove cooler bypass valve (3) from the radiator group. Put a plug in the opening of the radiator group to prevent loss of oil and to keep contaminants out of the hydraulic system. 4. Remove O-ring seal (4) from the cooler bypass valve. 5. Remove piston assembly (6) from valve housing (1). Remove the O-ring seal located inside the valve housing.6. Disassemble piston assembly (6) as follows:
There is spring force against the ring in the piston assembly. When the retaining that holds piston assembly (6) together is removed, the spring force will be released. To prevent possible personal injury, removal of the internal components in piston assembly (6) should be performed in a press to retain the springs and ring.
a. Put piston assembly (6) in a press. Install a suitable size drive plate on the internal springs. Put a slight amount of compression on the springs. Remove the retaining ring. Slowly release the spring compression. Remove the ring, inner spring, outer spring, cap and piston from the housing. The following steps are for the installation of the cooler bypass valve.7. Check the condition of all parts of the cooler bypass valve. If any of the parts are damaged, use new parts for replacement.8. Assemble piston assembly (6) as follows: a. Install the piston, cap, outer spring, inner spring and ring in the piston housing. Put the piston assembly in a press. Install a suitable size drive plate on the internal springs. Compress the internal springs until the