Exhaust gas return system
1 - throttle vacuum; 2 - exhaust gas pressure control valve; 3 - exhaust gas return valve; 4 - temperature vacuum valve
This system diverts part of the exhaust gases to the combustion chambers in order to reduce the harmful gases released during the combustion process. The control valve regulates the amount of gases returning from the exhaust manifold to the intake manifold depending on the vacuum in the carburetor. The illustration above shows a diagram of the system. The exhaust gas return valve controls the amount of gases that can again enter the intake manifold, while the valve located on the membrane can be closed and opened. The membrane is actuated by vacuum, which is obtained by opening and closing the throttle valve of the carburetor.
The temperature vacuum valve is located on the right side of the intake manifold. The valve reacts to the temperature of the coolant and opens or closes the vacuum port in the valve. If the hole is open, the carburetor vacuum enters the membrane of the exhaust gas return valve and actuates the valve seated in the conical seat. Next to the EGR valve is another pilot valve that monitors the exhaust gas pressure to actuate a diaphragm that carries the vacuum in the carburetor to the EGR valve.
The exhaust gas return system must be in good working order. Hoses must not be torn or damaged. With the engine turned off, the membrane of the exhaust gas return valve can be moved with your finger from the bottom up and down. She should move easily. All other inspection work must be carried out in a workshop, as the temperature vacuum valve, exhaust gas pressure control valve, etc. can also be damaged.