Why Is My Exhaust Smoke This Colour?
You can tell a lot about the health of your car’s engine from the colour of the exhaust fumes. Generally, exhaust smoke should be a thin colourless vapour, only visible during winter as a wispy white colour as a result of a condensation. If the smoke is any other colour, then it could be signs of a fault that needs addressing. Here are the most common unhealthy colours and what they mean.
White/grey
Faint white smoke in winter shouldn’t be a concern, as it is generally just condensation. However, if your exhaust is billowing thick white/grey smoke then this could be signs that you need to get things fixed.
Thick white smoke is generally the result of the engine burning too much coolant. This could be as a result of a cracked cylinder head that is causing coolant to enter the combustion chamber (look out for engine misfires and oil leakage). It may also be signs of a blown or damaged head gasket. This will generally result in coolant leaking, causing the engine to overheat, as well as bubbles in the radiator. The third possible reason may be some form of blockage near the coolant jacket that is causing your coolant to leak. In all cases, parts will probably need to be replaced. Whether going to a mechanic or fixing up yourself, make sure you get at least a six month guarantee on your parts, so that you can get your money back if it turns out to be another fault.
Black
Spotting black smoke is never a good sign and generally means that your engine is burning up too much fuel. This is usually the result of some form of blockage. The fuel line may be restricted or the fuel pressure regulator could be stuck. Occasionally the air filter may be a problem, in which case this will need to be replaced.
You should also look out for oil blockages. Oil may have started to congeal which will require an oil change (you can find out more at www.autoserviceprices.com/). Your oil filter may also possibly need replacing. As discussed earlier, make sure that any part replacements come with at least a six month guarantee, in case the problem persists (you will be able to get your money back).
Blue/grey
Blue/grey smoke is a sure sign that your engine is burning too much oil. This can be due to a number of things – generally worn seals or valves. A valve seal or valve guide may be causing oil to leak into the cylinder. Piston rings or cylinder walls may be worn and need replacing, causing blow-by. Alternatively, the blue/grey smoke may be the result of a faulty PCV, causing excessive crankcase pressure. If you’re not savvy under a car bonnet, you’re probably best visiting an auto-repair shop to properly diagnose this fault, as there can be all manner of places that oil could leak or block.