FILTER, AIR 0779838 - Caterpillar

Personal injury or death can result from escaping fluid under pressure.Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.Always use a board or cardboard when checking for a leak.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Caterpillar Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Before any tests are performed, release the pressure in the hydraulic system and prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation". Before any tests are performed, visually inspect the machine for oil leaks and damaged parts. Refer to Testing and Adjusting, "Visual Inspection".
Illustration 1 g01049978
(1) Test port for the pilot oil pressure. (2) Bank valve (Stabilizer).
Install a 8T-0856 Pressure Gauge on a 6V-3014 Hose Assembly . Install the other end of the hose to test port (1) for the pilot oil pressure.Note: Prior to testing the pilot system pressure, make sure that the piston pump is at the optimum pressure of 20700 kPa (3000 psi) for the 416D and 424D and 22800 kPa (3300 psi) for the 420D, 428D, 432D, and 442D.
Start the engine and run the engine at HIGH idle. Stall a cylinder in the loader circuit or the backhoe circuit. The pressure reading must be 3250 350 kPa (470 50 psi).
Stop the engine and engage the parking brake.
If the pilot system pressure is not within the specifications, the pressure reducing valve on the bank valve for the stabilizer must be replaced.