Vacuum diaphragm that controls the temperature control damper of the air entering the engine
The vacuum diaphragm is indicated by an arrow.
The location of the thermal valve in the air filter housing
The thermal valve is indicated by an arrow.
On engines with a carburetor, the thermostat maintains the temperature of the air entering the air filter within 25-35°C.
The damper in the air inlet allows hot or cold air to be supplied. The damper is controlled by a vacuum diaphragm, which reacts to the vacuum in the intake manifold. Vacuum supply to the damper is regulated by a thermal valve located in the air filter housing.
Examination
1. It is necessary to start checking the thermostat on a cold engine. When the engine is off, the thermostatic valve must be completely closed. The damper position can be determined both from the filter side and from the air intake side.
2. Start the engine and check that the choke opens fully at idle, opening the exhaust manifold-heated air to the air filter.
3. If, after starting the engine, the thermostatic damper remains closed, the thermostatic controller and membrane should be checked.
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