What causes water return when the engine coolant temperature is not high?

[PaulFitz]

The reasons for water return when the engine coolant temperature is not high are: 1. Uneven cylinder head surface; 2. Insufficient tightening torque of cylinder head bolts or failure to compress the cylinder gasket due to extended deformation of the bolts; 3. Presence of sand holes or cavitation defects in the water passages adjacent to the combustion chamber in the cylinder block or cylinder head, causing obstruction. The function of the engine is to convert the thermal energy of gasoline into mechanical energy by expanding the gas after combustion in a sealed cylinder, thereby pushing the piston to perform work. Methods for engine maintenance include: 1. Using qualified engine oil; 2. Using qualified coolant and antifreeze; 3. Regularly cleaning scale from the radiator; 4. Regularly removing carbon deposits from the engine; 5. Regularly replacing the three filters of the car; 6. Maintaining reasonable engine speed.