White Smoke From Exhaust: Main Causes and How to Fix

You don’t want to see your car smoking. It’s abnormal, as it points to a problem that needs to be fixed. Thin white smoke from the exhaust during the winter might be normal. But if the smoke is thick, you should look into it.

Whether the smoke comes out on startup or when accelerating, you can fix it with a few steps. Here’s a list of reasons for white smoke from exhaust and how to fix it.

Reasons for White Smoke from Exhaust

When you notice white smoke coming out from your car’s exhaust, it’s usually a result of the following culprits:

1.    Coolant Leak

A cracked coolant reservoir tank can allow coolant to leak into the engine’s combustion chamber. When the coolant burns within the cylinders, it creates a thick white smoke from the exhaust.

More common causes of a coolant leak include a cracked head gasket, cylinder head, or engine block. They usually occur due to overheating of your engine.

2.    Condensation Buildup

When there’s a condensation build-up within the exhaust system, you may notice a thin white smoke on startup. The smoke burns out fairly quickly once your engine warms up. Although this isn’t a serious issue, you should check it out if it’s accompanied by poor engine performance.

3.    Bad Fuel Injector

Your vehicle’s fuel injector delivers fuel to the combustion chamber, but it can’t control how the fuel gets sent. If it malfunctions, the chamber won’t receive the right amount of fuel at the right time. Too much fuel in the engine needs to be burned off.

The result is thick white or gray smoke from the exhaust. When this happens, you should call a professional to help you inspect and change the injection.

4.    Injector Pump Timing Is Off

This culprit only applies to diesel engines. The injector pump is responsible for sending diesel into the cylinders.

If its timing is off, the cylinders won’t receive the right amount of diesel when needed. An overrun of diesel could occur, which can cause thick white smoke to come out of the tailpipe.

5.    Engine Control Unit Error

Sometimes the cause of the white smoke is a faulty engine control unit. In this case, you need to repair or reset the engine control unit. This way, you’ll correct the fuel pump injector’s timing.

All you need to do to reprogram the computer is unplug the car battery for a few minutes. If the thick white smoke persists, you should take your car to a professional.

How to Troubleshoot and Fix White Smoke from Exhaust

The first thing you need to do when you notice white smoke coming out from your exhaust is check the coolant level. If the level is low and there’s no leak from the coolant reservoir tank, then the leak is a result of a crack in the cylinder head, engine block, or head gasket.

It would help to purchase an engine block leak detector kit, so you can tell when your coolant is contaminated. These steps will help you troubleshoot and fix white smoke coming out from the exhaust:

Step 1: Open the hood

Make sure the engine is cool before you remove the reservoir cap or radiator cap. If the engine is hot, allow it to cool for at least one hour before attempting to check the coolant.

Step 2: Check the coolant level

Your car needs to be parked on a flat surface while you check the coolant level. Open the coolant reservoir and check the coolant chamber. You will see the markings on the plastic overflow bottle, saying “Low” and “Full,” or similar terms.

Use a funnel to fill the reservoir until the level reaches “Full.” You may check the level by putting a stick into the reservoir.

Step 3: Inspect other engine components

Once you have determined that the amount of coolant in the engine is adequate, you should inspect other engine components. Cracks or other damages may cause the coolant to mix up with fuel or engine oil. Determine the part that caused the leak by performing a cooling system pressure check.

Apply pressure to the system up to the range specified on the radiator cap. This way, you can confirm that there’s a leak if the system can’t hold pressure for more than two minutes. In the absence of an external leak, the cause of the white smoke is most likely a crack in the engine block, head gasket, or cylinder head.

Final Thoughts

White smoke from exhaust should never be overlooked. It is a problem to the environment and a signal that your car needs attention. But, there’s no need to panic, as you can fix the issue in no time with the tips we provided. In all, always remember to take care of your car engine.


How can oil leak into the combustion chamber?

This usually happens when leaky valve seals or piston rings allow oil to flow into the combustion chamber. When you fail to lubricate engine components properly, they will wear out prematurely, which results in oil leaks. It leaves you with expensive replacements and repairs that you don’t want to deal with.

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