The causes of white exhaust smoke can vary; however, it is common to see white exhaust smoke when first starting a car, especially on cooler days. This is generally steam caused by condensation. As the engine warms up and the condensation dissipates the white exhaust smoke (steam) is no longer seen. If excessive white exhaust smoke is present well after the engine warms up, it is necessary to have the car inspected for possible internal coolant leaks. Indicators of an internal coolant leak include billowing white exhaust smoke accompanied by a sweet odor or a low coolant reservoir level. An internal coolant leak can also contaminate the engine oil giving it a frothy, milky appearance. Even small amounts of coolant entering the combustion chamber will produce white exhaust smoke.
One of the main causes of white exhaust smoke and coolant loss is a cracked or warped cylinder head, a cracked engine block, or head gasket failure caused by overheating. A cracked head may allow coolant to leak into one or more cylinders or into the combustion chamber of the engine. Dirty coolant, a poorly maintained cooling system, a low coolant level, or a non-functioning cooling fan can cause engine overheating. In addition, engine wear can eventually cause the gaskets to lose their capacity to seal properly allowing internal coolant loss. Intake manifold gasket and head gasket failures are two of the most common sources of internal coolant loss caused by engine wear.
Never remove the radiator cap or coolant reservoir cap while the engine is hot or running as it can cause serious injury; always allow the car to cool down completely first. Checking for a low coolant level in the reservoir is the first step in determining if coolant loss is causing the white exhaust smoke. If the coolant reservoir is at the proper level but excessive white exhaust smoke is present, a cooling system pressure check is required to determine where, if any, coolant leaks are located.
Related Questions and Answers
Should I Be Worried about White Exhaust Smoke Coming from a Car?
White exhaust smoke from your car, depending on when you see it, can be extremely serious or it can mean almost nothing. If you only see it when you first start the car in the early morning when the temperature is low, you have nothing to worry about. However, if you see it all the time, you can have a simple problem, or a very serious problem. If the smoke dissipates shortly after leaving the tailpipe, this means it's actually steam and signifies a blown head gasket. This is bad. If the cloud isn't too bad and doesn't dissipate, then you could be burning oil. Depending where the leak is, this can be very bad or not terribly bad. No matter what, you should have it looked at.