Is it cold inside the car? At the most inopportune moment, did the engine boil? Unsure about the normal operation of the engine? All these questions can arise due to a malfunction of one device of the cooling system - a thermostat, the main task of which is to regulate the flow of engine coolant, depending on its operating mode.
Instructions
Step 1
In order to determine the malfunction of the thermostat and the reasons for its occurrence, remember how it works. The thermostat consists of a body, in which a liquid or solid filler with a high coefficient of linear expansion is placed. The body is connected to the valve.
While the coolant is cold, the valve is in the down position (the path for fluid movement through the radiator is closed). As the engine warms up, so does the thermostat housing. When the temperature reaches the set values (82-90 °, depending on the type of thermostat), the body expands and opens the valve. The coolant begins to flow into the radiator, where it is cooled.
Step 2
What happens when the thermostat is defective? In the event that the valve remains open (does not go down to the lower position), the engine runs cold for a long time when starting. This leads to increased mechanical wear of cylinders and pistons, the engine lubrication system does not work well, because cold viscous oil worse comes to rubbing engine parts.
When the valve is permanently closed, the engine start mode is normal. However, when the temperature rises, the valve does not open, and the liquid moves only along the engine cooling jacket and the stove in the car. This leads to overheating of the engine with all the ensuing consequences.
Step 3
If the above signs are present, exclude other reasons that may lead to this. To do this, check:
- coolant level;
- tension of the water pump drive belt;
- serviceability of temperature sensors.
Step 4
In the event that the cause of the malfunction of the cooling system could not be determined, check the thermostat. Take it out and inspect it carefully. If the main parts are intact, and the valve is dirty, clogged with scale, try to clean it.
To find out if cleaning was effective, place the thermostat in a container of water and start heating it. Measure the temperature with a thermometer with a scale of 100 degrees or more. When the thermostat heats up to the opening temperature (usually this figure is stamped on the thermostat body), the valve begins to open. If this does not happen, the thermostat is faulty and needs to be replaced.
