What are the reasons for the thermostat not opening?
2 Answers
The reasons for the thermostat not opening are: 1. Internal damage to the thermostat or damage to the thermostat opening valve; 2. Blockage in the water passage. 3. Frozen radiator; 4. Water temperature is too low. The thermostat automatically adjusts the amount of water entering the radiator based on the temperature of the coolant, changing the circulation range of the water to regulate the cooling system's heat dissipation capacity, ensuring the engine operates within an appropriate temperature range. The thermostat must maintain good technical condition; otherwise, it will severely affect the normal operation of the engine. The function of the thermostat is to prevent the engine from becoming too cold. The main type of thermostat used is the wax-type thermostat. When the cooling temperature is below the specified value, the refined paraffin in the thermostat's temperature-sensitive body is in a solid state, and the thermostat valve closes the channel between the engine and the radiator under the action of the spring. The coolant returns to the engine via the water pump, performing a small circulation within the engine.
I've been driving for many years and have fixed quite a few issues myself. The problem of a thermostat not opening is quite common. The main reason is that the thermostat itself gets stuck in the closed position, most often due to internal rust or sediment buildup. For example, using aged or cheap coolant can easily lead to dirt accumulation, making the valve immovable. Another possible cause is spring failure, such as loss of elasticity due to prolonged high-temperature fatigue. Once, my old car's temperature suddenly spiked, and when I pulled over to check, I found the thermostat jammed with rust and had to replace it. The consequences can be serious—engine overheating can damage the water pump or even the cylinder head, leading to costly and labor-intensive repairs. So, I recommend using high-quality coolant during regular maintenance and not waiting until problems arise. If you notice abnormal engine temperature, get it checked by a professional immediately, and always keep the cooling system clean.
