Is an engine coolant temperature of 65°C to 70°C normal?
3 Answers
An engine coolant temperature of 65°C to 70°C is normal. Here are the relevant details: Engine temperature too low: This can make the air-fuel mixture difficult to ignite or cause delayed combustion, resulting in reduced engine power. The engine oil becomes thicker due to low temperature, increasing viscosity and resistance to moving parts. Incompletely vaporized fuel washes away the oil film on friction surfaces like cylinder pistons and piston rings, dilutes the oil, accelerates component wear, or causes incomplete combustion of the mixture, increasing fuel consumption. Engine temperature too high: Excessive thermal expansion of air reduces the engine's volumetric efficiency, disrupts the air-fuel ratio, enriches the mixture, leads to incomplete fuel combustion, and also increases fuel consumption.
Seeing the coolant temperature at 65-70°C, I can't help but comment! This temperature is really too low. Normally when I start a cold engine, it stabilizes around 85°C. If the temperature gauge still sticks at 70°C after driving for a while, there's an 80% chance the thermostat is stuck in the open position, allowing coolant to continuously circulate through the radiator for cooling. Long-term low-temperature operation is particularly harmful to the engine - poor gasoline atomization increases carbon deposits, high oil viscosity leads to poor lubrication, and fuel consumption will noticeably rise. I recommend checking the thermostat as soon as possible. Replacing it with an OEM part only costs around a hundred bucks, which is much more economical than engine repairs.
The mechanic explained this in detail during my last car repair. The normal coolant temperature should stabilize around 90 degrees Celsius with minor fluctuations. 65-70 degrees is only sufficient for maintaining the warm-up phase of a cold engine. The key is observing performance after continuous driving—if it fails to rise above 85 degrees within ten minutes, it usually indicates a thermostat system malfunction. I've encountered similar situations before, which ultimately turned out to be a failed thermostat spring causing premature engine coolant circulation for heat dissipation. Untreated, this issue can lead to carbon buildup in combustion chambers and easily cause emission levels to exceed standards during tailpipe testing.
