Why is My Car Smoking?

There are various causes of smoke coming from your car. Take note of where the smoke is coming from, the color of the smoke, and any accompanying odors.
Written by David Ghanizadeh-Khoob
Reviewed by Melanie Reiff
There are various causes for why your car could be smoking, ranging from minor issues to major problems requiring expensive repairs. White smoke commonly signifies burning coolant, black smoke is often a sign of raw fuel combustion, and blue/gray smoke usually indicates burning oil. 
One of the most worrisome experiences you can face as a driver is seeing smoke coming from under the hood. Unfortunately, it is no easy task to identify the issue, especially on the side of the road without the proper tools.
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Why is my car smoking under the hood?

There are a number of reasons why a car can start to smoke. The most common reason is motor oil (or other liquid) spilling or leaking on a hot engine. In these cases, the smoke is usually harmless but may still require attention.
If there are clouds of smoke coming from your tailpipe or under the hood, this usually signifies a serious mechanical or electrical issue
You should pull over, take note of where the smoke is coming from, what color the smoke is, whether the car is overheating, and when the smoke appears. Make sure you let the car cool before you start working on the issue.

What different colors of smoke mean

Smoke from under the hood

White engine smoke: Coolant leaking on a hot engine will produce white smoke and a sweet pungent odor. Coolant leaks are often the result of damaged radiator hoses or a cracked engine block
Black engine smoke: There are lots of potential causes of black smoke coming from under the hood. One common cause is an electrical failure/burned wire. 
Black smoke is often the result of burning raw fuel, so if there is an issue with the fuel injector, pressure regulator, carburetor, or inlet manifold, these can cause inefficient fuel combustion in the engine and produce smoke.

Smoke from the tailpipe

White exhaust smoke: White smoke coming from the tailpipe usually means coolant is being burned in the combustion chamber
This can be caused by:
  • A broken head gasket
  • A cracked engine block
  • Damaged cylinder heads
Black exhaust smoke: Black smoke from the tailpipe when a car starts up is quite common and is often not a serious concern. If there is persistent black smoke, though, it likely requires attention and is usually the result of:
  • A clogged or dirty air filter
  • Bad fuel pressure regulator
  • A leaking or clogged fuel injector.
Blue or gray exhaust smoke: Blue or gray exhaust smoke usually signifies oil burning in the engine. You might also notice your car misfiring when starting or shaking when idling, and a pungent, bitter odor. Some common causes of oil burning in the engine include:
  • Worn pistons 
  • Damaged seals
  • A faulty PCV valve
  • Head gasket failure
  • Inlet manifold leaks
Key Takeaway The location, color, and smell of the smoke can be useful for identifying the issue. If you are unsure of the cause, take your car to a mechanic as soon as possible to sort out the problem before it gets worse.

Why is my car smoking but not overheating?

If you notice your car is smoking but not overheating, the issue is often minor. If it persists, though, you will want to take your car in to get inspected. Some common reasons a car might smoke without overheating include:
  • Oil spillage or leakage
  • Oil filler caps
  • Faulty wires
  • Spilled or leaking coolant

What to do if your car is smoking

If your car is smoking, pull over and assess the situation. Look for the above signs, and check if the car is overheating or if any warning lights have turned on. Do a visual inspection to see if anything obvious is wrong. 
If the situation seems serious or if you notice any leaks then either call a tow or b line it to a mechanic. Never work on a hot engine, and wait for it to cool down.
If you notice any fire, turn off your engine, pop the hood but don’t try to prop it open, move away from the car, and call the fire department.

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