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Understanding Exhaust Smoke and What To Do About It

Understanding Exhaust Smoke and What To Do About It


You'll most likely know what your exhaust is, but do you know what it does and more importantly what to do if smoke starts coming out of it?

What does your exhaust smoke mean?

A car’s exhaust is a component that pretty much everyone knows about. It has also become the subject of much debate, with rising emissions regulations forcing manufacturers to make their cars - and therefore their exhausts - cleaner. 

But what is an exhaust for and what does the smoke coming from the back of it mean? Let’s take a look.

So what is an exhaust actually for?

As the name would suggest, it’s there to exhaust fumes away from the engine and the car’s passengers. All engines produce six emissions of which three are toxic - carbon monoxide, nitrogen oxide and nitrogen monoxide. A catalytic converter then filters out these harmful gases to make them inert. 

Do exhausts serve any other purpose?

Of course. Exhausts - and the silencers fitted within them - work to make a car quieter. Without a silencer, even the smallest of cars can turn into a really loud machine - so it’s best to make sure they’re in good condition.

Over time, exhausts can corrode and holes can form. You’ll notice this when your car starts sounding louder than usual.  

What does the smoke mean?

Ideally, your car shouldn’t be producing any smoke from the exhaust. On a cold morning, you might notice some white condensation coming from the pipe, but this isn’t anything to be worried about. 

However, black exhaust smoke means that your car could be burning too much fuel. This could be from a clogged air filter and on diesel-powered cars, this is particularly noticeable. The unburnt fuel mixes with engine lubricant and can, on occasions, create great plumes of smoke. This needs to be checked out by a mechanic. 

Milky white smoke which doesn’t clear once the car is warm is a more concerning issue. It could point towards a leaking head gasket, which would result in the engine becoming too warm and overheating. This smoke could also mean that the engine’s cylinder head is cracked - and this is something you need to get checked out right away. 

Finally, there’s blue smoke. If you see this coming from your exhaust, then it could mean that your engine is burning oil from a leak. There are all manner of reasons behind blue smoke appearing so, again, it’s best to get it checked by a professional.