A roadside expert from The AA has shed light on what to do if you notice different-coloured smoke emanating from your car’s exhaust. While white smoke on a chilly morning might simply be due to condensation, a smoking exhaust can be a red flag for underlying issues.
Depending on the colour, the problem could range from burning oil – blue smoke – to excessive fuel consumption – black smoke. Grey smoke, on the other hand, may indicate a faulty turbocharger, oil burning, or issues with the fuel system.
Ignoring these warning signs can lead to serious complications or, in extreme cases, pose a significant safety risk. Shaun Jones, an AA patrol expert, has shared his advice on how to handle white or blue smoke emanating from your exhaust.
What different colour exhaust smoke means and what to do
White smoke, while not always a cause for concern, warrants caution. Shaun advises: “If you notice white smoke coming from your car’s exhaust, it’s best not to continue driving. While short drives may be safe if the smoke is due to condensation, other causes like a blown head gasket or coolant leaks can worsen with driving.”
In the case of a blown head gasket, coolant seeps into the combustion chamber, burning with the air-fuel mixture and producing smoke, reports Leicestershire Live. This issue demands immediate attention to prevent further engine damage.
Shaun advised: “If there’s a coolant leak, it’s important to locate and repair the source, whether it’s the radiator, water pump, or worn seals.”
A leaking radiator can lead to head gasket failure, which allows coolant to leak and burn with the fuel. White smoke is a sign of a cracked engine block, where coolant leaks into the combustion chamber through a crack, mixes with the air-fuel blend and burns off. Symptoms include engine overheating, coolant loss, oil contamination, and reduced performance.
A cracked cylinder head can also cause coolant to mix with the air-fuel mixture, resulting in white exhaust smoke. Shaun added: ” A cracked engine block or cylinder head may need specialist welding or parts replacement.”
Foam in the engine oil is a sign of coolant contamination, often due to a blown gasket or cracked block, leading to coolant burning. Engine overheating can produce white smoke and further damage the engine block or cylinder head, causing cracks and coolant leaks, exacerbating the issue. If the coolant level drops significantly, it could indicate a leak or a faulty component like the water pump or radiator.
Properly filling and sealing the coolant system is crucial to prevent this problem and ensure the engine stays cool. Air in the cooling system can also cause issues. Trapped air in the cooling system can prevent coolant from flowing correctly, potentially leading to engine overheating. In situations where coolant can’t circulate as it should, it might cause localised overheating and even push coolant into areas where it doesn’t belong, such as the combustion chamber.
Shaun mentioned: “If air is trapped in the cooling system, the system is likely to need bleeding.” He emphasised that this task should be performed exclusively by someone with appropriate training.
When it comes to spotting blue smoke from your car exhaust, it’s typically an indication that oil is being burned within your vehicle. Here are some common culprits:
– Worn piston rings can allow oil to seep past and enter parts of the engine where it shouldn’t be. Replacing worn rings is often a complex and costly fix.
– Leaking valve seals are designed to stop oil from entering the engine cylinders. However, if they fail, oil may start leaking into these areas and the faulty seals would need replacing by a professional.
– A broken head gasket can lead to oil making its way into the engine, and it’s essential to get a damaged gasket replaced to halt any oil leaks.
– Issues with the turbocharger on cars equipped with one can also result in oil leaks if it’s malfunctioning. Fixing a faulty turbocharger is necessary for resolving such issues.
Shaun cautioned drivers, saying: “For blue smoke, it’s important to act quickly. Avoid driving, as continuing to drive can worsen the problem, leading to more damage and costly repairs. You may also experience reduced fuel efficiency and engine performance issues. Blue smoke will cause your car to fail an MOT test and might violate emissions laws.
“It’s best to get your car checked by a mechanic as soon as you notice the smoke to prevent further damage. If concerned, consider breakdown cover for professional assistance and car maintenance advice.”