What Causes the Coolant Temperature to Be Too Low?
2 Answers
The main reasons for excessively low coolant temperature include: malfunctioning temperature gauge and wiring, damaged coolant temperature sensor, thermostat valve stuck open, failure of the shutters to close due to a faulty temperature control switch, and fan motor circuit issues causing the fan to run continuously or failure of the silicone fluid clutch in vehicles equipped with such fans. Below are methods to diagnose the causes of low coolant temperature: 1. In low ambient temperatures, check if the shutters close properly or if a thermal cover is missing. 2. After a cold start, open the radiator cap and accelerate the engine to observe the speed and volume of water flow. If the water flows quickly and in large volume, it indicates the thermostat is stuck open or missing, and it should be replaced or installed. 3. Start the engine cold (for vehicles with electric fans), the electric fan should not operate at this time. If the electric fan runs, it suggests a faulty temperature control switch, which should be replaced.
I've been driving all my life, and encountering coolant temperatures that are too low is nothing new. It's mostly due to the thermostat valve getting stuck in the open position. In hot weather, it should close to let the water temperature rise, but if it's broken, it stays open, keeping the engine cool. I remember last winter, the temperature gauge showed only 65 degrees. The engine was noisy and consumed more fuel while driving. I had an old mechanic check it, and sure enough, it was a thermostat issue. Replacing it fixed the problem. Letting this go on for long isn't good—it causes severe engine wear, makes cold starts difficult, and leads to more carbon buildup. During regular maintenance, pay attention to the coolant ratio; don't just dilute it with water, as that lowers the boiling point and makes it harder to heat up. Also, old antifreeze that's deteriorated can affect performance, so regular replacement helps prevent such issues.
