What Does It Mean If There's White Smoke Coming From Your Vehicle's Exhaust?

Lisa Steuer McArdle
Dec 17, 2021 · 3 min read
Half the battle with car maintenance is recognizing signs that your car is having a problem, and some of those signs are subtle. For instance, smelling gas could indicate a problem
Other signs that your car needs help are glaringly obvious. One of the most worrisome of these is smoke from your exhaust. This is how you diagnose your smoking car.
Thick plumes of white smoke from a car often come from water or coolant burning.

Normal exhaust

According to The Drive, the gas coming from your tailpipe should be clear. At most, water condensation on cold days can make it look like a thin, white wisp of cloud.
This color comes from the gas that comes from gasoline and air combusting. The gas gets scrubbed in the catalytic converter before it comes out the tailpipe too.

White smoke from exhaust

If some chemical other than gasoline and air gets into your combustion chamber, the resulting smoke will take on a different color. Thick plumes of white smoke come from water or coolant burning.
Water or coolant gets into your combustion chamber in three ways. It can get through cracks in the cylinder head or engine block, or it can get through a blown gasket head.
You can find out if you have a coolant leak by checking the coolant level. If it is low and you don't see a leak, your gasket may be blown. You can also get an engine block leak detector kit to find a leak.
A cracked engine block, cylinder block, or blown gasket head is a major repair. You will probably want to hire a mechanic right away to deal with it. Your other options are rebuilding the engine, replacing the engine, or buying a new car.

Other colors besides white smoke from exhaust

Exhaust can let you know that something is wrong by emitting smoke of other colors besides white. According to Auto Express, the other colors are black, gray, and blue.
Black smoke from a gasoline car might mean that too much fuel is being burned. Your air filter may need changing, or your fuel injectors may be clogged.
A diesel car might produce black smoke if soot builds up in the diesel particulate filter. You can dislodge the soot by driving fast.
Gray smoke can be caused by burning excess oil or a turbocharger having trouble. Another cause of gray smoke is the positive crankcase ventilation valve malfunctioning.
A car with an automatic gearbox might produce gray smoke if transmission fluid leaks into the engine. You will need to take it to the mechanic in that case.
Blue smoke has a few causes. Engine oil could be burning in your fuel system, possibly because your valve seals or piston rings are breaking down. Cars with high mileage are prone to this.
On the other hand, engine oil might have accidentally spilled on your engine when you changed the oil, and that is harmless. The blue will go away quickly.
You might want to check your engine oil regularly and top off often if you are losing engine oil.
A turbocharged car could produce blue smoke if the turbocharger is worn out. You will need to either replace or rebuild it.
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