What Causes A Car To Smoke Under The Hood[ Reasons & Solutions ]

Nothing is more frightening than watching smoke coming out of your car’s hood. And every time it happens, the owners keep wondering, “What causes a car to smoke under the hood?”

Well, the smoke under your car’s hood can originate for many reasons. The diagnosis depends on the color and type of smoke. It can be anything, ranging from a leak in the coolant to a defective overheating engine.

So, if you’ve encountered such an incident, go through this article to learn more about the reasons.

What Causes A Car To Smoke Under The Hood?

Imagine driving your car downtown and noticing a cloudy or whitish smoke emerging from under your car’s bonnet. Horrifying, isn’t it?

There could be many reasons behind the smoke. First of all, let’s have a look at the things you should check to dig inside the cause:

  • Color of the smoke
  • Site of the smoke
  • Onset of smoke
  • Engine overheating

The common reasons for smoking under a car hood are:

  • Leakage of head gaskets
  • Malfunctioning of the coolant system
  • Damaged power cables
  • Rusted pistons
  • Defective fuel valves

Depending on the color of the smoke, we’ll try to figure out what is causing the smoke under your car’s hood.

You can read:

Causes Of Black Smoke From The Engine

If you notice black smoke under the car hood, that means the problem is associated with the burning of the fuel. The following can be the reason behind it.

Leaking Fuel Injector

Through the fuel injector, the petrol or diesel flows into the engine. Blockage by any debris inside the injector or any possible leakage can cause black smoke.

Faulty Regulation Of Fuel Pressure

The fuel pressure regulator controls the amount of fuel that goes into the engine. Get it checked by your mechanic to detect any problems.

Carburetor Defect

Older vehicles use a carburetor to combine air and fuel. You’ll see black smoke when this component malfunctions and feeds the combustion engine too much gasoline or fuel.

Your automobile will be consuming too much energy and releasing too many emissions if the issue isn’t repaired by an expert immediately.

A Clogged Inlet Manifold

The car’s cylinders receive a fuel and air solution from the inlet manifold.

If the inlet manifold gets jammed, only a small amount of this mixture will be able to pass to the combustion chamber. This may result in the emission of contaminated smoke.

If you have enough knowledge, you can clean it in your garage. 

Causes Of White Smoke From The Engine

While operating properly, a combustion engine creates a blend of water vapor and carbon dioxide. This is largely undetectable as it is vented through the vehicle’s exhaust system.

A faulty engine will start burning excessive white contaminated fuel and produce excessive white smoke. White smoke can be of 3 types, mainly: thin vapor, smoke with a sweet smell, and normal white smoke.

They can indicate the following malfunctions:

Leakage Of External Coolant

Any leakage in the external leakage can cause white smoke. When the coolant comes in contact with the overheating engine, it creates a vapor-like white smoke.

The coolant may leak due to a broken coolant hose or blown gasket. Also, engine overheating can cause the coolant to overflow.

Broken Head Gasket

If the head gasket of your car is blown, it will cause leakage of coolant. Soon, it reaches the engine compartment and causes white smoke.

Even if the leak is unnoticeable, it will still cause smoke inside the engine. Additionally, it may result in the overheating of the engine and damage it ultimately. It is a fairly expensive repair, but a necessary one to protect your motor.

Cracked Cylinder Head

It works exactly in the same manner as the blown head gasket. If the cylinder head is broken, it will cause leakage of coolant all over the engine.

Leakage Of Valves And Seals

All the valves and seals in the engine must work properly to ensure a good result. Any damage to the valve will cause leakage of oil.

Initially, the color of the smoke might seem white, but it turns into a blue color when the problem gets bigger.

How Much Does It Cost To Repair Smoking Engine Problems?

The repair cost entirely depends on the type of damage inside the engine. A blown gasket repair would cost you something around $150, whereas a fuel injector repair might cost over two grand.

If the problem is complicated, the total may go higher than $2500.


Smoke coming out from under your car’s hood is a sign of an underlying issue. Some of the causes are major, while others are minor. In this article, we tried to show you what causes a car to smoke under the hood.

So, if you ever notice a similar problem, do not panic and take immediate action to fix it.

Hi, I am Ashley Kiser a professional automotive blogger. I have worked in the automotive industry for over 5 years. I am passionate about cars and love sharing my knowledge with others. I hope this blog will help you make the best decisions when it comes to your car.

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