White Smoke Coming From Your Vehicle’s Exhaust: Diagnosis and What To Do

Thick plumes of white smoke from a car's exhaust come from water or coolant burning. Here's how to diagnose white smoke and what to do about it.
Written by Lisa Steuer McArdle
Reviewed by Kathleen Flear
Dec 17, 2021
Half the battle with
car maintenance
is recognizing signs that your car is having a problem—whether you can
smell the car's gas
or feel the car shaking too much, it's important to stay ahead of any potential problems.
One of the most worrisome problems is white smoke from your exhaust. Read on to learn how to diagnose the problem with your smoking car.
Thick plumes of white smoke from a car often come from water or coolant burning.

What does normal exhaust look like?

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. If your exhaust isn't clean or a thin white wisp, you could have trouble.

What does white smoke from your exhaust mean?

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. The other problem colors are black, gray, and blue.

Black smoke

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

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

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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Aig
Chubb
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CSE
Dairyland
DirectAuto
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Libertymutual
Gainsco
Mapfre
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Nationwide
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Safeco
Travelers
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