Why is the engine temperature low?
3 Answers
Causes of low engine temperature include: 1. Thermostat not sealing properly: The coolant continuously undergoes major circulation through the large radiator, preventing the engine from retaining heat and resulting in low water temperature. Normally, the thermostat should remain fully closed when water temperature is below 95°C to maintain minor coolant circulation, and only open fully when coolant temperature reaches above 95°C. 2. Corroded thermostat housing: Corrosion in the thermostat housing connects the major and minor coolant circuits, keeping the coolant in major circulation. Low engine temperature leads to poor fuel atomization, allowing condensed gasoline to leak from the combustion chamber into the crankcase, diluting the engine oil and compromising cylinder wall lubrication, which accelerates cylinder wear. Low temperature also increases oil viscosity, causing poor lubrication and accelerated component wear, particularly significantly shortening engine service life due to cylinder wall wear. Additionally, low temperature reduces engine power and fuel efficiency.
With over 30 years of auto repair experience, I've found that low engine temperature is often caused by a faulty thermostat stuck in the open position, allowing continuous coolant circulation that prevents proper warm-up. Coolant leaks or water pump issues can also cause engine overcooling, especially noticeable during short winter drives. Low temperatures are problematic as they reduce combustion efficiency, increase fuel consumption and emissions, and cause thick oil to lubricate poorly, accelerating engine wear. For diagnosis, first check the temperature gauge reading. If consistently low, feel the radiator for temperature differences and use a scanner to read trouble codes if needed. Thermostat replacement is usually straightforward, but don't delay repairs to avoid damaging other components. Regular cooling system maintenance and inspections can prevent such issues.
I've been driving long-haul trucks for twenty years, and low engine temperatures are common in cold weather or during frequent stop-and-go driving. In winter, the engine needs time to warm up after starting, and if the trip is under ten minutes, the coolant temperature won't reach the operating range. A failing thermostat can cause excessive cooling—I once encountered this while delivering goods in Northeast China, where the engine stayed too cold, increasing fuel consumption by 20%. Poor lubrication in low temperatures accelerates engine wear and makes the cabin uncomfortably chilly. Nowadays, I use an engine cover insulator in extreme cold or choose longer routes to ensure proper warm-up. If the dashboard consistently shows low temperature, it's best to have it checked by a professional.
