People are only just realising what different colours of exhaust smoke mean – and how to fix major issues
A CAR expert has revealed what different colours of exhaust smoke mean – and when to take action.
Dean Gibson explained that different shades of smoke can indicate a wide range of problems, or even be completely harmless.
Writing for Auto Express, he said that white, blue, grey and black smoke can all be pumped out of your pipes depending on what’s going on under the hood.
Some could indicate serious trouble, but most cases can be easily fixed if addressed quickly.
First of all, white smoke is probably the most common to see coming out of an exhaust line.
Fortunately, it’s also the least serious to deal with.
Most white smoke is actually not smoke at all, but water vapour from either the aircon condenser or evaporating coolant.
However, Dean wrote: “If the white smoke coming from the exhaust is thicker and doesn’t stop, it is still steam, but also an indicator of a more severe issue that will be caused by your car’s coolant leaking into the engine.
“This can be caused by a failed head gasket (the seal between the engine block and the head that sits on top), which could be a pricey repair, but not as expensive as needing to repair a cracked engine block or cylinder head.”
Next up, blue smoke is actually a sign of engine oil being burned in your engine.
This could be due to a leak in the lubrication system, the oil being overfilled or simply a bit of oil being spilt into the exhaust during a fill-up.
It can also indicate worn-out valves or piston rings, which can be expensive to fix, and can cause your oil to run down quicker, which can damage your engine.
Thirdly, Dean ran through the meaning of grey smoke.
He said: “Like blue smoke, grey smoke could be a sign of excess oil burning somewhere in the engine, or a turbo needing attention.
“If you drive a car with an automatic gearbox, then another reason for grey smoke might be that transmission fluid is being drawn into the engine through a leak in the system.
“Again, this could be a costly repair and will definitely need attention from a garage.”
Finally, the meaning of black smoke varies depending on the type of fuel your car takes.
If it’s a petrol model, it means too much fuel is being burnt, which can usually be fixed by changing the air filter.
However, if that doesn’t remedy the issue, you could have an issue with your fuel injectors, which will need to be professionally cleaned.
On the other hand, if it’s a diesel, it could be simply down to a build up of soot in the exhaust system.
Dean advised: “To remedy this, the best course of action is to get the fuel/air mixture flowing through the car faster, by driving it faster.
“Find a nearby dual carriageway or motorway and accelerate your diesel car to 70mph briskly, this should dislodge the soot which will appear as a ball of black smoke behind the car, and probably leave soot deposits on the road, too.”