Pic. 4.43. Expansion tank: 1 - safety ring; 2 - gasket; 3 – sensor; 4 - float with lever
The control system works from a floating sensor installed in the expansion tank (pic. 4.43). If there is not enough coolant, the contact closes.
The cause of malfunction may be a burnt out lamp, a broken sensor or a broken wiring.
If the warning light does not come on when the ignition is turned on, it may be burned out.
If the lamp does not turn off when the engine is started, but the coolant level is normal, then the sensor is faulty. This can be checked by disconnecting the contact from the sensor. If the lamp goes out, the sensor is faulty. Remove the sensor, check the float and other elements. Replace sensor.
Loss of coolant
If a large amount of coolant is lost while driving, be sure to replace its loss, in extreme cases, use water for this purpose.
With a large temperature difference (cold water - hot engine) the cylinder head may warp. Upon receiving the so-called «cold shock» the engine block can give a microcrack. Therefore, allow the engine to cool down before adding fluid and find out the cause of the loss of coolant as soon as possible.