Have you ever driven your car and seen white smoke coming out from under the hood? This condition is scary and alarming, especially if you don’t know what is causing it. White engine smoke is not something that should occur under normal circumstances.
We analyze the causes of white engine smoke and analyze possible solutions. We can also estimate what a repair could cost you.
When your combustion engine works as intended, it produces a mixture of carbon dioxide and water vapor. This is channeled through the exhaust system and mostly goes unnoticed. However, when there is a problem with the operation of the engine, it may start to burn something else.
White smoke indicates some form of contamination. Instead of burning air and fuel, the engine burns something else.
The most common reason for white smoke coming out of the engine is due to external coolant or an oil leak. External coolant leaks can also be caused by an overheated engine, which pushes coolant out of the system and into the engine compartment.
Here is a more detailed list of the reasons why white smoke is coming out of your engine:
What causes white engine smoke?
1. External coolant leak
If the white smoke is coming from the engine bay, you most likely have an external coolant leak or an overheated engine. When the coolant comes into contact with the hot part, the vapor generates white smoke.
Coolant leaks can be caused by many different things, such as broken coolant hoses or faulty seals. If you can see a refrigerant leak, you can check out this article on refrigerant leaks for more information.
White smoke from the engine compartment can also be caused by the engine overheating causing coolant to leak out of the cooling system. If the smoke is coming from the exhaust and not the engine compartment, continue!
RELATED: 9 Causes of an Overheating Car Engine
2. Burned head gasket
When the head gasket blows, coolant leaks into the engine bay or exhaust pipe. If severe, the leak may be visible on the outside of the exhaust manifold. However, these problems often go unnoticed.
Still, it will create white smoke coming from the engine. It can also cause the engine to overheat, resulting in serious engine damage. This is one of the most expensive repairs to perform, but it is necessary if you want to save your engine.
3. broken cylinder head
Additionally, if a cylinder head cracks, coolant can leak into the cylinder or combustion chamber. As it mixes with the fuel, it will create the same white smoke seen with a blown head gasket.
As coolant leaks into the engine, it cannot do its job, putting the engine at risk of overheating. You can look in the oil or coolant reservoirs to see if there are signs that the two have mixed.
4. Defective fuel injector
The injector ensures that there is the correct amount of fuel to mix with oxygen for combustion. Most modern engines are highly calibrated to ensure that nothing affects this mixture.
However, if the injector is not working properly, the mixture may receive too much fuel. Since this fuel will not be able to burn properly, you will notice white or gray smoke coming from the exhaust.
5. Poor diesel injection pump timing
You can also have problems with your diesel engine if the mixture is not perfect. If the injection pump timing is incorrect, it will act like a bad fuel injector on a gasoline engine.
Poor timing produces a mixture that contains too much fuel. Since it doesn’t burn, white smoke ends up coming out of the engine.
6. Leaking seals/valve
The engine is made up of many seals and valves that need to do their job for everything to function properly. If any of the piston valve seals or rings begin to deteriorate, oil may begin to leak.
However, burnt oil tends to be more blue in color but is easily confused with white smoke. It will appear whiter when the leak is minimal and will eventually turn bluer.
3 Types of white engine smoke
- fine steam
- smelly smoke
- normal white smoke
Your car usually produces vapor as part of the exhaust. If you are not used to seeing it, or if you start your vehicle on a cold day, you may be more alarmed.
When temperatures drop, the exhaust vapor can appear more intense, sometimes being mistaken for smoke. However, if that smoke clears quickly, you probably have nothing to worry about.
When the white smoke is dense and accompanied by a sweet smell, you can bet on a coolant leak. Coolant is very mild, this is the same reason why it is recommended to keep antifreeze away from animals as they will be attracted to it and drink it.
However, when coolant mixes with fuel, it burns in the engine and creates white engine smoke. It will also produce a distinctive sweet smell unlike any other automotive fluid. As we discussed above, a blown head gasket or cracked cylinder could cause this situation, both of which are expensive repairs.
normal white smoke
If you notice white smoke coming from the engine but don’t smell anything special, it could be due to condensation in the exhaust. Like regular water vapor, condensation can build up in the exhaust, especially if you start the vehicle in the morning.
Imagine the dew forming on the grass. It’s the same situation but in the exhaust of your car. If so, it will burn quickly. If the smoke persists, there is something wrong with your engine that needs to be investigated.
Engine Smoke Repair Costs
The cost to repair the white smoke situation varies depending on the cause. As we have illustrated, several conditions can occur. If it’s something simple like a bad gasket, the replacement should cost you less than $150, including labor.
All other repairs tend to be expensive. For example, a leaking valve or seal can cost between $50 and $1,000. A broken fuel injector or pump could cost up to $2,000. The most serious is a blown head gasket or cracked cylinder, which is not only expensive but also difficult to repair. Depending on the type of car you drive, you could spend up to $2,500 to fix these problems.
However, whenever you see white smoke coming from the engine, you want the problem fixed. Failure to do so will cause major engine damage that will require a complete replacement.