320B, 320B L,320B LN, 320B N, & 320B S EXCAVATORS MACHINE SY Caterpillar

NOTE: The cooler bypass check valve is located behind the left rear access door near the hydraulic oil cooler.

Fluid Spillage Containment

Care must be taken to ensure that the fluids are contained during performance of the inspection, the maintenance, the testing, the adjusting and the repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to the "Tools And Shop Products Guide, NENG2500" the tools and the supplies suitable to collect and contain any of the fluids in Caterpillar machines. Dispose of the fluids according to local regulations and mandates.

1. Start the machine, and fully extend the stick and the bucket. Lower the stick and the bucket to the ground.

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At operating temperature, the hydraulic oil tank is hot and under pressure. Hot oil can cause burns. To prevent possible personal injury, release the pressure in all of the implement hydraulic circuits (the boom, the stick and the bucket) before any of the hydraulic lines or any of the components are disconnected or removed.

2. Release the pressure in all of the implement hydraulic circuits (the boom, the stick and the bucket) before any of the hydraulic lines or any of the components are disconnected or removed. Release the pressure as follows:

a. Shut off the engine and place key in the "ON" position. Put the hydraulic activation control lever in the "UNLOCK" position.

b. Move the control levers for the boom, the stick and the swing to all full stroke positions. This will release any pressure that might be present in the pilot system.

c. Return the key to "OFF" position.

d. Slowly loosen the fill plug on the hydraulic tank and release the pressure.

e. Tighten the fill plug on the hydraulic tank. Tighten the fill plug to a torque of 68 ± 7 N*m (50 ± 5 lb ft).

f. The pressure in the hydraulic system has been released and the hydraulic lines and the components can be removed.

3. Drain the oil from the hydraulic oil tank into a suitable container for storage or disposal. The capacity of the hydraulic oil tank is 130 liters (34 U.S. gal).

4. Disconnect four pipe assemblies (1) from the housing for the cooler bypass check valve. Put plugs in the ends of the pipe assemblies to prevent loss of oil and to keep contaminants out of the hydraulic system.

5. Remove two bolts (3). Remove the housing and cooler bypass check valve (2). Remove the cooler bypass check valve from the housing.

NOTE: The following steps are for the installation of the cooler bypass check valve.

6. Check the condition of the O-ring seals used in the end of pipe assemblies (1). If the O-ring seals are damaged, use new parts for replacement.

7. Install the cooler bypass check valve and housing (2) in the reverse order of the removal steps.

NOTE: Refer to the topic "Lubricant Viscosities and Refill Capacities" in the "Operation & Maintenance Manual" for the proper filling procedure and the proper levels for the hydraulic system.

8. Fill the hydraulic oil tank with oil to the correct level.