What Causes the Thermostat to Fail to Open?
2 Answers
Thermostat fails to open due to: internal thermostat damage or failure of the thermostat opening valve, or possibly the water temperature being too low. The thermostat automatically adjusts the amount of water entering the radiator based on the coolant temperature, altering the water circulation range 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. If the thermostat's main valve opens too late, it can cause the engine to overheat. Conversely, if the main valve opens too early, it prolongs the engine warm-up time, resulting in the engine temperature being too low. In summary, the thermostat's role is to prevent the engine from becoming too cold.
I've encountered a similar issue before. A thermostat that won't open usually indicates a problem with the cooling system, most commonly due to internal sticking or blockage. When the thermostat is stuck in the closed position, coolant can't circulate to the external engine radiator, causing the water temperature to rise rapidly. You might see the dashboard temperature gauge spike or warning lights come on. I think there could be several reasons: first, the thermostat itself may have aged and deformed, with a failed spring preventing the valve from opening; second, the coolant might be too dirty or have air bubbles blocking the valve; third, related sensors like the water temperature sensor could be faulty, sending incorrect signals that mislead the system. Checking it yourself is quite simple - after turning off the engine and waiting for it to cool, feel the upper radiator hose. If it's cool while the lower hose is hot, that basically confirms the thermostat isn't opening. Never force it open, as the engine could overheat and be ruined. I recommend going to a repair shop as soon as possible to replace the part, to avoid breaking down on the road.
