When your vehicle is running properly there shouldn't be any signs of smoke when driving. If there's blue, white or black clouds spewing out of your exhaust, then you know there is a problem. The different colours have very different causes and we’ll talk about what this means for your vehicle in this blog below.

Blue Smoke

Blue smoke is most often produced when oil leaks into the engine’s cylinders and burns as part of the combustion process. There are a number of reasons for this happening: worn piston rings, worn valve guides and valve seals. Any of these could be letting oil through when they should be lubricating the moving part causing the coloured smoke.

There are some other potential causes too. Fuel additives like Seafoam can also cause coloured smoke because the liquid is eating away at the built up carbon in your engine leading to blue tinted smoke. If this is the case, it’s not a permanent problem and after the Seafoam runs its course the blue smoke should disappear.

If you’re not sure blue smoke is coming out of the exhaust, a telltale sign is compression loss in the cylinder because it’s being worn down. Also you can watch your oil consumption by checking your dipstick and if you’re running through oil pretty quickly, you have yourself a leak.

White Smoke

White smoke typically has two causes:

1. There’s coolant spilling out of a broken or warped head gasket into the cylinder, causing the engine to overheat and spit out thick white smoke.

2. The other cause is condensation. Condensation happens, you can’t avoid it, but don’t worry it’s just liquid escaping your cold engine as it warms up and you’ll know it if you see a thin puff of smoke or steam that looks closer to a vapour. If the smoke is still there after the engine is warmed up then it’s probably coolant. Make sure if it’s coolant you get it fixed right away, if you keep using it in that condition there will be a lot more costly problems down the road.

Black Smoke

Black smoke is often accompanied by poor fuel economy, bad starting, loss of power in your vehicle and your spark plug will be caked with black soot.

Black smoke is clearly visible in light backgrounds and is made of soot particles escaping the engine as a result of it failing to properly combust. The engine is failing because there’s too much fuel being shot into the engine or what’s often referred to as “running rich”. Running rich has to do with the air-fuel balance in the carburetor and there are lots of factors that can change the amount of fuel/air your engine needs. Things like adding or taking off performance mods or buying jets too wide for your carburetor can cause too much fuel to come out.

It might sound silly, but the colour of your smoke really does matters when it comes to diagnosing problems with your vehicle. Do you have any experience with these different coloured smokes? Share your stories in the comments.


  1. What Does the Smoke From my Exhaust Mean: http://www.autoguide.com/auto-news/2015/04/what-do...
  2. Engine Smokes What to Do: http://atomium.eu/home/engine-smokes-what-to-do/
  3. What is Seafoam and What Does it Do: http://mechanics.stackexchange.com/questions/15653...
CarbCarburetorRunning leanRunning richSmoke

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