The lower chamber of the pneumatic drive is used to control the air supply to the engine in the warm-up mode. Such control is stopped after the operating temperature of the coolant is reached.
The upper chamber of the pneumatic drive is used to control the air supply to the engine, in the idle mode of a warmed-up engine. Such control begins when the ignition is turned on and the engine is started. If the vacuum tube that goes to the upper part of the pneumatic drive is removed on a diesel engine running during warming up, the engine will stall even with the ignition switch on.
The pneumatically operated valve at the inlet to the intake manifold opens to reduce vibration at idle or when the diesel engine is stopped. It also opens halfway in the event of a system malfunction to prevent diesel engine "runaway".
Electropneumatic switching valves communicate the chambers of pneumatic actuators of gas exchange control systems in diesel engines either with the atmosphere or with rarefaction (vacuum).
Resistance check - Fig. 8
1. Disconnect the valve connector.
2. Measure the resistance between the valve terminals.
Connector Colors - Black / Brown
Resistance at 20°C - 38.5-44.5 Ohm
Fig. 9 Checking the resistance between the terminals of the electropneumatic valves
Checking the operation - Fig. 9
1. Turn off the ignition.
2. Disconnect the valve connector and vacuum hoses.
3. Blow into nozzle 1: air should come out into filter 2.
4. Connect battery power to the valve terminals.
5. Blow into nozzle 1: air should come out through nozzle 3.
Fig. 10 Checking the operation of electropneumatic valves