What is the phenomenon of engine seizure in cars?

[McCody]

Engine seizure in a car can cause the engine to suddenly stall and fail to start. The reasons for engine seizure are as follows: Excessively small clearance between piston and cylinder: During the friction process between the piston and cylinder, if the clearance is too small, it can lead to insufficient oil film formation, resulting in dry friction and ultimately causing seizure. When replacing cylinder liners and pistons, it is essential to select pistons and liners from the same group. Before installation, it is best to measure the pistons and cylinder liners using a bore gauge and micrometer to ensure the clearance meets specifications. If a bore gauge and micrometer are unavailable, a feeler gauge can also be used. Measurement method: Insert the feeler gauge blade into the clearance between the cylinder and piston skirt (in the direction perpendicular to the piston pin installation). The ideal condition is when there is slight resistance when pulling the feeler gauge, but it can still be moved freely. Proper clearance and good lubrication will prevent seizure. If the piston ring end gap is too small, it will accelerate wear between the piston rings and cylinder liner, and in severe cases, lead to cylinder scoring or seizure. Therefore, when replacing piston rings, ensure their end gaps comply with specifications. Insufficient lubrication oil: During engine operation, the cylinder liner and piston movement areas primarily rely on oil splashed onto the cylinder walls for lubrication. If the oil pan is low on oil, the amount of oil splashed onto the cylinder walls by the rotating motion of the crankshaft and connecting rod big end will be insufficient, preventing the formation of an oil film. This worsens the working conditions of the piston inside the cylinder, increases temperature, and causes excessive piston expansion, leading to seizure. Therefore, it is necessary to add an appropriate amount of qualified lubrication oil. However, adding too much oil can also result in oil burning issues.