Exhaust Smoke: What Does The Colours Mean?
Like a patient who exhibits certain symptoms when they’re sick, your car has ways of telling you it isn’t well. Although most of the time you need a mechanic’s tool set and know-how to fix the problem, there are a few initial diagnostic tools which come free to everyone: sight, smell, hearing, and exhaust smoke.
Many underlying engine problems can begin to be solved by making an exhaust smoke colour diagnosis. The important thing as a driver is to pay attention to your car’s operation and notice if anything seems off. Excessive exhaust smoke means you have an engine issue on your hands, which could be as simple as changing the air filter, or as big as a crack in the engine block itself.
Before you go into panic mode, narrow down the problem according to the colour of the smoke.
If your vehicle’s engine has an internal oil leak that is allowing it to be burnt up inside the combustion chamber there will be a production of blue smoke. This type of leak is very dangerous for your motor as it can result in increased friction between the moving parts, resulting in major wear and tear. If you ever notice blue smoke coming out of your tailpipe be sure to visit an auto mechanic right away. Sometimes oil leaks just need to be monitored but much more frequently they will need to be repaired right away.
The darkest of smokes emitted from the exhaust is generally nothing much to worry about and is linked with the balance of combustion controlled by the ECU. A darker visible exhaust gas is due to an overly-rich fuel mixture, created when the air/fuel ratio descends below the optimum Stoichiometric ratio (14.7:1 in a petrol engine, 14.5:1 for diesel). The spark at ignition can only combust a certain amount of fuel in a cycle, so unburnt fuel is pushed out into the exhaust system and is combusted downstream of its intended combustion chamber.
These conditions can be caused by a leaking fuel injector, a blocked fuel return pipe, a broken oxygen or airflow sensor or a fuel pressure regulator stuck closed. A dirty air filter will also prohibit nice clean air from making it through to the combustion chamber. Not only will this constrict the volume of air entering the cylinders but it will also make for less efficient combustion dues to the presence of unwanted contaminants.
Not to be confused with the normal white vapour that disappears quickly under normal conditions due to condensation or on cool morning start ups, heavy white smoke is cause for concern. This means that coolant has made its way into the combustion chamber, and coolant only get there if you’ve got a bigger problem that should be addressed immediately or you risk overheating and major engine damage. Best case scenario is a blown head gasket, and while that’s not exactly fun, it doesn’t require major overhaul. Other possible culprits may be a damaged cylinder head (overhaul) or cracked engine block (engine replacement). In any case, if you notice persistent, thick, white smoke out of the tailpipe, stop driving the vehicle and call a mechanic.
It is important to pay attention to the visual clues that there is a problem occurring within your vehicle, such as excessive and colourful exhaust smoke. Ultimately, exhaust smoke colour diagnosis may not tell you the exact problem, but it can give you a much better idea of what you’re dealing with and whether you could attempt to fix it yourself.