It regulates the flow of coolant. It is a spring-loaded valve controlled by a wax pellet. When the engine is cold, the valve is open; when hot, the valve closes. When installing the thermostat, the jiggle valve should be in the uppermost position.

The problem describes the function and installation of a thermostat in a cooling system, specifically focusing on its operation and positioning. Here are the known conditions extracted from the description: 1. **Function of the Thermostat**: It regulates the flow of coolant. 2. **Mechanism**: It is a spring-loaded valve controlled by a wax pellet. 3. **Operation**: - When the engine is cold, the valve is open. - When the engine is hot, the valve closes. 4. **Installation Position**: The jiggle valve should be in the uppermost position during installation. ### Explanation of Each Condition 1. **Regulation of Coolant Flow**: The thermostat plays a crucial role in maintaining the engine's temperature by controlling how much coolant flows through the engine and radiator. This ensures that the engine operates efficiently and prevents overheating. 2. **Spring-Loaded Valve and Wax Pellet**: The thermostat uses a wax pellet that expands when heated. This expansion pushes against a spring-loaded valve, causing it to close as the engine reaches its optimal operating temperature. This mechanism allows the engine to warm up quickly by restricting coolant flow until the desired temperature is achieved. 3. **Temperature Response**: - **Cold Engine**: When the engine is cold, the wax pellet is not expanded, keeping the valve open. This allows coolant to circulate through the engine, helping it to warm up. - **Hot Engine**: As the engine heats up, the wax pellet expands, closing the valve and preventing coolant from flowing back to the engine until it cools down again. 4. **Installation Position**: The jiggle valve is a small valve that helps to release air from the cooling system. Installing it in the uppermost position ensures that any trapped air can escape, preventing air pockets that could disrupt coolant flow. ### Conclusion The thermostat is essential for regulating engine temperature, and its proper installation is crucial for the cooling system's efficiency. The jiggle valve's position is particularly important to ensure that air does not interfere with the coolant flow.