What is the reason for white smoke coming from the exhaust pipe after carbon cleaning?
3 Answers
The reasons for white smoke coming from the exhaust pipe after carbon cleaning are: 1. Residual cleaning agent sprayed inside during cleaning; 2. When the vehicle is started, the residual cleaning agent will burn along with the fuel, and if the air-fuel mixture is too rich, it will produce white smoke. The exhaust pipe is installed between the engine exhaust manifold and the muffler, allowing the entire exhaust system to have flexible connections, thereby reducing vibration and noise, facilitating installation, and extending the life of the exhaust muffler system. The maintenance methods for the exhaust pipe are: 1. Regularly check if the exhaust pipe is cracked; 2. Regularly inspect the exhaust pipe for abnormal noises; 3. Regularly check for any foreign objects inside the exhaust pipe; 4. Let the engine idle for 10 minutes before starting to expel accumulated water inside.
Last time after cleaning the carbon deposits, I also encountered white smoke from the exhaust pipe. I specifically consulted a repair shop technician to understand the reason. It's mainly due to the steam produced when the cleaning agent is sprayed into the engine for combustion, similar to the white vapor when water boils. It's particularly noticeable during cold starts right after cleaning, and you can see a large cloud of white fog in the rearview mirror while driving. There's no need to panic about this short-term phenomenon—it usually clears up after driving a few kilometers to expel the residues. However, if thick smoke persists for several days, it might indicate damage to the engine seals—such as piston rings or valve stem seals failing, allowing coolant to leak into the combustion chamber. In this case, the white smoke may carry a slightly sweet smell, and the engine may lose coolant without reason. It's recommended not to shut off the engine immediately after cleaning carbon deposits; instead, drive at high speed for a while to ensure the exhaust is thoroughly cleared. If continuous smoke occurs, take the car directly to the repair shop to check the seals, as engine repairs can be costly.
Last time after my car's carbon cleaning, the exhaust pipe was emitting white smoke, and I thought the engine was damaged. Later, after checking information and consulting friends, I realized that the cleaning agent entering the combustion chamber would form water vapor, which is a normal physical reaction. Especially during cold starts, the lower temperature of the exhaust pipe makes it easier for the vapor to condense into a white mist. It usually dissipates after driving for about ten minutes, and in my case, it returned to normal after a three-kilometer highway drive. However, be cautious if white smoke persists for a long time, as it might indicate that strong cleaning agents have corroded the oil seals or piston rings, causing coolant to mix into the combustion chamber. In such cases, the white smoke is particularly dense and carries the distinct sweet smell of coolant. It's advisable to use neutral cleaning agents and have the mechanic take the car for a short drive after the procedure. If you're doing it yourself, remember to warm up the engine before cleaning to prevent dissolved carbon deposits from clogging the catalytic converter. If white smoke continues for more than three days, promptly check the exhaust composition to avoid turning a minor issue into a major repair.
