Bangkok: Causes of white smoke from a car are being shared online, such as worn injector O-rings and washers, as well as warped cylinder heads.
According to Thai News Agency, the "Sure Before Sharing" center verified the information with Aphinu Wiriyakobkul, a car tester and expert, better known as "Uncle Nu" from the Grand Story channel, who confirmed the information through an interview on March 13, 2026. White smoke coming from a vehicle is a dangerous sign that should not be ignored and is often indicative of issues within the engine's combustion system.
Many times, drivers notice white smoke emitted from their car's exhaust and question its significance and potential danger to the engine. Automotive experts explain that "white smoke," which may exhibit a bluish tint, signifies a malfunction in the combustion system. The primary causes of this issue can be categorized into several areas, including problems with the fuel injection system, cylinder and piston issues, malfunctions within the cylinder head and cooling system, and other related causes.
In terms of the fuel injection system, worn injector O-rings are commonly found in diesel engines and can lead to rough engine performance, a fuel odor, and a "hissing" sound near the injectors. These worn O-rings can also affect gasoline engines, causing unstable idle speeds and fuel leaks.
Issues within the cylinder and piston, such as worn oil scraper rings and worn piston rings, result in abnormal engine oil consumption and increased white smoke, especially during acceleration. Cylinder wear can also lead to engine oil leaking into the combustion chamber.
Malfunctions in the cylinder head and cooling system, like a damaged cylinder head gasket, can be identified by thick white smoke, coolant loss, engine overheating, and air bubbles in the radiator. A warped cylinder head may result from engine overheating, cooling system problems, or a clogged radiator.
Other causes include turbocharger problems, which can lead to white smoke in vehicles with forced induction systems, and a clogged or faulty PCV valve, impacting engine compartment pressure and exhaust gas venting.
To address the issue of white smoke, experts recommend prompt vehicle checks to prevent further damage and expensive repairs. Checking engine compression can provide insight into the engine's condition. In cases of minor wear, using higher viscosity engine oil might reduce white smoke and delay the need for major repairs.
In conclusion, white smoke is typically a sign of engine oil burning with fuel, indicating a problem that requires immediate attention to prevent severe engine damage.