Many car owners are often worried when opening the lubricant cap and seeing a white slight or thin wisp of smoke coming from the engine. Many people think that this is a sign that the engine has been "white", worn cylinders or seriously degraded. However, according to a technician at the Ninety Eight Auto Motorcycle Repair, Maintenance and Care Center (Thu Duc City, Ho Chi Minh City), just relying on this phenomenon is not enough to conclude that the engine is damaged.
To accurately assess, the engine needs to be returned to a normal operating state, i.e., it has been operating for enough time to reach a temperature of about 85-95 degrees C. If you check immediately after starting, the amount of air observed will not accurately reflect the actual condition of the engine.
When the engine has reached the standard operating temperature, the appearance of a thin layer of white vapor or light water vapor at the oil cap is quite common. The reason is that the internal temperature of the engine is high, causing oil and water vapor to rise during operation. This is not an abnormal sign if the amount of vapor is low and does not include other signs.
What users need to note is the phenomenon of white vapor or air escaping too strongly at each beat, accompanied by continuous evaporation. According to Ninety Eight Auto, this may be a sign that pressure from the combustion chamber is falling into the battery due to the cylinder, shaft or piston being worn. If the engine vibrates, operates weakly, consumes unusual oil or reduces power at the same time, the possibility of damage will be higher and needs to be checked soon.
However, observing the amount of air escaping from the oil cap is only a preliminary check step. This phenomenon is not sufficient basis to conclude whether the engine is "out of breath" or needs to be overhauled. To accurately determine the engine condition, the car needs to be measured for combustion chamber pressure using specialized equipment at a garage or genuine dealer. The measurement results will help determine the sealedness of the combustion chamber and detect worn details if any.
Ninety Eight Auto recommends that users should not be too worried when they see a slight white vapor emanating from the oil cap on the engine that has been heated. This is a common phenomenon in many cars that are still operating normally.
Only when the air escapes too much, prolongs or appears with other abnormal signs such as oil loss, power loss or vibration should the car be taken to a repair facility for in-depth inspection. Diagnosing the cause correctly will help car owners avoid unnecessary repairs and save costs.
