by Charlie Hare
image by exhaust fulmes by bilderbox from Fotolia.com
When internal combustion engines operate, the combustion of air and fuel that takes place inside the cylinders releases moisture from the air, which is usually sent to the exhaust system in the form of water vapor or steam. If the engine and exhaust system are cold, moisture can condense from the vapor to form a liquid that can drip down the tailpipe.
It is normal for a small amount of water to drip from the tailpipe of a cold engine and should not be a cause for concern. Some car exhausts can constantly leak if used for short trips only, as the engine and exhaust system may never get hot enough to prevent moisture from the exhaust from condensing back into liquid. The greatest danger from chronic small amounts of water in the exhaust system is the possibility of rusting the system prematurely. Many exhaust systems are made of stainless steel to prevent rust.
If there are large amounts of water dripping from the exhaust, it can be a symptom of a leaking head gasket, which is a serious and expensive repair. Usually when the head gaskets start to leak, the exhaust column becomes quite thick and light in color and can give off a sweet smell. This occurs when engine coolant boils out of the combustion chambers. Seek mechanical help immediately.
When the air is humid, there can be more moisture in car exhaust. Also, if the air is cold, some moisture may drip from the exhaust pipe until the engine and system warm up. If the amount of moisture dripping from the tailpipes seems excessive, have a trusted mechanic check the vehicle.