After-treatment exhaust systems have become mandatory additions in modern diesel engines thanks to environmental protection. The systems ensure that diesel engines do not emit toxic fumes during operation. Although older diesel engines do not have the feature, they should still emit limited quantities of carbon. However, it is only possible with a well-maintained engine, which should only emit white smoke until it reaches normal operating temperature. Therefore, if you notice different coloured smoke coming from your exhaust, it is a sign that your diesel engine needs servicing. This article explores common smoke colours that signify issues with a diesel engine.
Also referred to as dirty smoke in engine maintenance quarters, grey smoke is a combination of partially burnt fuel and exhaust gas ejected from a combustion chamber. Several factors can explain the presence of partially burnt fuel, with the most common one being excessive fuel in a combustion chamber. If there is more fuel than a diesel engine can burn, the chances are high that most of it will be pumped out and mix with exhaust gas. Another reason why your engine might not burn the fuel entirely is a restricted air inlet. It prevents adequate amounts of oxygen from reaching an engine and aiding the complete fuel combustion. In this case, diesel services need to unblock the air inlet to allow unrestricted flow of oxygen.
An idle engine and low temperatures are the perfect conditions for white smoke in diesel engines. However, the white smoke should clear once an engine reaches optimal temperatures, provided it is in good condition. In most cases, a cold engine is to blame for white smoke because it prevents particles in the combustion chamber from burning fully. For instance, a limited load range causes diesel engine temperatures to drop significantly. Consequently, it delays the combustion process and causes some fuel to remain unburned. Correcting the limited load range allows a diesel engine's temperatures to rise and reach optimal levels, eliminating the white smoke.
The primary function of engine oil is to lubricate all moving parts and protect them from the effects of constant friction. Other functions include cooling, cleaning and protecting components against corrosion. Therefore, when you see blue smoke coming from an exhaust system, you need to see your mechanic immediately, especially if your vehicle is consuming a lot of engine oil. The reason is that engine oil is burning, resulting in blue smoke. The main culprits are worn-out piston rings, failed valve sleeves or leaking oil hoses. A diesel engine specialist will inspect all the parts to identify the source of leakage and replace the faulty components.
Contact a local diesel service to learn more.