Why is white smoke coming from my car exhaust?

Regular car maintenance can help you stay on top of any potential problems, but sometimes there are causes for white smoke which will mean a trip to your local garage.

In this guide, we explain the causes and solutions for white smoke coming from your vehicle.

Why is white smoke coming from my car's exhaust?

White smoke from your car's exhaust can be a sign of several potential issues, ranging from minor to serious.

Most commonly, it indicates that coolant or water is entering the engine’s combustion chamber due to a crack or damage.

This can happen due to a blown head gasket, a cracked engine block, or a warped cylinder head.

Take your car to a trusted local garage to find a solution to the problem, as it needs to be addressed immediately. Ignoring it could lead to a large bill for a replacement engine.

These three components all have water or coolant flowing through them. If damaged, they can leak into the engine, where it turns into steam and exits through the exhaust.

However, don’t jump to conclusions if you see white smoke. If the smoke is thin and disappears quickly, especially on a cold day, it might just be condensation burning off, which is normal.

However, if the smoke is thick and persistent, then it is likely coolant, and a more serious issue is present.

Driving with this condition can lead to engine overheating and severe engine damage if not addressed promptly.

Other, less common causes include a faulty fuel injector or a fluid leak into the engine.

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What causes white smoke from a car?

There are several main reasons why there might be white smoke coming from your vehicle’s exhaust. Here we have profiled the most common causes:

Blown head gasket

A blown head gasket can cause white smoke from the exhaust by allowing coolant to leak into the engine’s combustion chamber and other components around it.

When the coolant or water burns, it creates thick white steam that exits through the exhaust system.

This issue often comes with overheating, loss of coolant, and a sweet smell in the smoke.

Cracked engine block (cylinder)

A cracked engine block or cylinder can cause white smoke from the exhaust by allowing coolant to seep into the combustion chamber.

Cracks often occur from overheating or freezing and typically require extensive repair or engine replacement to resolve.

Regular maintenance can help prevent this – and is something that can be picked up in a full service.

Damaged radiator

A damaged radiator can lead to engine overheating by failing to properly cool the engine coolant.

While it doesn’t directly cause white exhaust smoke, it can contribute to overheating-related issues like a blown head gasket.

Sometimes water can leak from the radiator, also leading to white smoke.

Issues with hoses, seals, or connectors

There are many components that go into making an engine work smoothly for long periods of time.

Sometimes, they can get damaged over time – leading to issues such as leaks and corrosion.

This can play a role in water getting into the engine, causing white smoke to exit from the exhaust.

Condensation

Condensation forms when moisture in the exhaust system evaporates, especially on cold mornings. This creates thin, white vapor that quickly disappears.

Unlike smoke from engine problems, condensation is harmless and temporary, usually lasting only a few minutes.

Why is the smoke white in colour?

The smoke appears white in colour because it's made up of water vapor or steam.

When coolant leaks into the engine’s combustion chamber, due to a blown or damaged head gasket, it gets heated and turns into steam.

Unlike the darker colour of smoke from burning oil or fuel, steam is light and often appears white as it condenses in cooler air upon exiting the exhaust.

This visual difference helps mechanics diagnose engine problems based on smoke colour.

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How to get stop white smoke from coming out of your car

To stop white smoke from coming out of your car’s exhaust, you first need to identify and fix the underlying cause.

Remember, that if you are unsure, your local garage will be able help with this issue – and avoid any further damage to the exhaust system or the engine.

The most common reason is a coolant leak into the engine, often due to a damaged head gasket or engine cylinder.

These issues require mechanical repair and, in some cases, major engine work.

A mechanic can perform a coolant test to pinpoint the problem and make the necessary fixes.

If the head gasket is blown, replacing it usually resolves the issue. However, if the engine block (cylinder) is cracked or broken, then you may need to repair or replace those components.

Sometimes, the mechanic can use head gasket sealer, but it’s not a long-term solution, and the white smoke will likely return in a short period of time.