If your vehicle suddenly puts out a lot of white smoke from the exhaust or constantly uses excess amounts of engine coolant, chances are you have a bad head gasket on your hands. Head gaskets help keep engine coolant and oil from leaking into the combustion chamber. White smoke is usually a big indicator of a failing head gasket that has failed with age, excessive amounts of heat or excessive amounts of torque applied to the head bolts. Detecting a bad head gasket is a relatively simple task that can be done without removing the cylinder head.
Check the vehicle's coolant level whenever the vehicle is in use. Fill the vehicle with coolant to the MAX fill line and then observe the coolant level through the opaque coolant expansion tank during each trip. If the coolant level continues to drop while driving and there are no external leaks, there may be a leak through the head gasket.
Check the vehicle's engine oil. Locate the engine's oil dipstick and withdraw it from the dipstick tube. Check the current oil level and then dab a small amount of oil on a piece of paper. If the oil appears to be a milky colour, coolant is entering through the oil passageways and cylinder head due to a failing head gasket.
Start the engine and stand at the rear near the exhaust pipe. Observe what comes out of the pipe. Large quantities of white smoke will indicate a failing head gasket. The exhaust will also have a semi-sweet odour and a high amount of humidity due to the engine coolant leaking into the combustion chamber.