IMPELLER-PUMP 7E8175 - Caterpillar

Note: It is possible to hear the sound of air leakage. Air leakage can be observed by applying soapy water to connections, to valves and to hoses.
Start the engine and allow the air pressure to reach the cutout pressure. Stop the engine. Note: The governor cutout pressure is 830 35 kPa (120 5 psi). If the governor cutout pressure is not correct, see the Systems Operation/Testing And Adjusting, "Governor (Air Compressor)".Note: Include all hoses, lines and connections in your investigations.
Check from the air compressor to the primary air tank. The check should include the air compressor governor and the air dryers.
Check for air leakage at the drain valves of the air tanks. Check for air leakage at the relief valves for the air dryers and for the primary air tank.
Check for air leakage from the primary air tank to the service brake air control valve.
Check for air leakage in the service brake air control valve.
Check for air leakage from the service brake air control valve to the retarder air control valve.
Check for air leakage in the retarder air control valve.
Check all hoses, lines and connections between the following components: the service brake air control valve, retarder air control valve, the torque converter and front brake cooling diverter valve and the brake air relay valves.
Check the brake air relay valves and the torque converter and front brake cooling diverter valve for air leakage.
Check for air leakage from the brake air relay valves to the brake master cylinders.
Check the brake master cylinders for air leakage.
Check all hoses, lines and connections between the following components: secondary air tank, the secondary brake air control valve and the air control valve for the parking brake.
Check for air leakage in the air control valve for the secondary brake and in the air control valve for the parking brake.
Check from the air control valve for the parking brake to the parking and secondary brake valve.
Check the parking and secondary brake valve for air leakage.
Check all hoses, lines and connections between the following components: the primary air tank, the air start relay and the air starting motor gp.
Check from the secondary air tank to the air system pressure protection valve.
Check for air leakage in the air system pressure protection valve.
Check all hoses, lines and connections between the following components: the air system pressure protection valve, the circuit for the horn and the solenoid for the air starting motor gp. Note: While you check for air leakage, check the exhaust passages for restrictions. (The restrictions may be from mud or from dirt.) A restriction in an exhaust passage will slow down the release of pressure air during normal operation. A restriction in an exhaust passage may even prevent the release of pressure air during normal operation.Service Brake Check
Note: The service brake air control valve activates the front brakes and the rear brakes.
Start the engine and allow the pressure to reach the cutout pressure.
Move the parking brake control to the OFF position. Do not depress the