How to Determine if a Thermostat is Faulty?
2 Answers
Methods to determine if a thermostat is faulty are as follows: 1. When the engine starts cold, if there is still coolant flowing out from the upper water chamber inlet pipe of the radiator, it indicates that the main valve of the thermostat cannot close. 2. When the engine coolant temperature exceeds 70°C, if there is no coolant flowing out from the upper water chamber inlet pipe of the radiator, it indicates that the main valve of the thermostat cannot open normally. Below are the inspection methods for the thermostat: 1. First, check if the coolant level is sufficient. 2. Inspect the water flow rate after starting the engine. 3. After the water temperature rises, check the changes in water flow rate and temperature.
I frequently deal with car maintenance, and there are several practical methods to determine if a thermostat is functioning properly. You can start the vehicle and let it idle for a few minutes, then observe the changes on the temperature gauge: if the temperature rises very slowly or not at all, the thermostat may be stuck in the open position, allowing coolant to circulate continuously; if it overheats quickly, it may be stuck in the closed position. You can also feel the upper radiator hose near the engine—if the upper part is hot and the lower part is cool, the thermostat is working correctly; otherwise, it's likely faulty. I usually use simple tools like an infrared thermometer for assistance, but don’t overlook related maintenance, such as aging coolant, which can also affect performance. Regular checks can save you from costly repairs. Safety first—a faulty thermostat can lead to engine overheating, especially before long trips. It’s best to spend ten minutes on a quick inspection to avoid breaking down midway.
