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The quickest way to check any car engine is to give a close look at the car exhaust system through its tail pipe. In ideal condition you should not be able to see or feel the car smoke from the exhaust tail pipe, unless it's a diesel engine car that result in black smoke (normal). All petrol engine cars since last 10-15 years have been optimized to the extreme to not to pollute the environment. This resulting in most modern engines are getting very efficient and with all the current rules and regulations relating to environmental pollution, they will produce little to no smoke at all. Smoke from your exhaust can be one of the signs that your cars engine is having problems but what does it mean? Let's look at it here in more detail: Black smoke Black smoke indicates a rich air/fuel mix, i.e. too much fuel in the mix and not enough oxygen to burn it all. Some of the most common problems that can causes black smoke from car exhaust are: Dirty/blocked air filter Faulty temperature sensor Injector/s stuck open Blocked fuel return line to tank Faulty FPR (Fuel Pressure Regulator) White smoke White smoke is steam, caused by water/coolant entering the combustion chamber. This can be caused by: Faulty head gasket Cracked cylinder head Cracked engine block Problem with turbocharger (Only water cooled turbos) Blue smoke Blue smoke is caused by oil entering the combustion chamber. This can be caused by: Worn valve stem oil seals Worn piston rings Worn cylinder walls Worn turbo seals PCV (Positive Crankcase Ventilation) valve stuck open Here are the few videos to help you identify the colour of your car exhaust smoke: **DISCLAIMER** I accept no responsibility for any misdiagnosis of exhaust smoke, this is just a simple guide on some of the possible causes. Always consult a qualified mechanic and read the workshop manual for your car before attempting any repairs.

While blue color could symbolize trust and wisdom, but with a car it could well symbolize the American concept of depression associated with the blue color. So, if blue smoke comes out of your car’s exhaust, it is a clear sign of worry -- Oil is burning, which means it is coming out of its supposed domain and leaking and getting burnt along with fuel to result in blue vapors. This could be because the piston rings or valve guise seals have got damaged. The leak may let the oil reach the combustion chamber, where it gets burnt. Another reason could be that the car is turbocharged and the smoke is a signal that the blower’s time is up. The blue smoke should not be confused with white smoke you see when you start your car. White smoke is water vapor collected while the car was parked. To find the damage, you could first check the valve seals. The valves are covered in oil on top and the seals are designed to stop this oil from getting into the engine. Once worn out, the valve seals will be helpless and let’s oil get into the engine which gets burnt along with the fuel and air creating the blue smoke. If the valve seals are fine, check Positive Crankcase Ventilation (PCV) valve. The job of this valve is to release the pressure that gets built in the oil pan into the intake manifold which is connected to the engine air filter. If the PCV valve is damaged, it will mix the air with oil and other gases in the engine, which gets burnt resulting in the blue smoke as well. If valve seals and PCV valve are fine, then the damage could be in the engine. The engine pistons have metal rings around them called Piston rings. When the pistons move up and down and if the rings are worn out, oil from beneath the piston can come up, which gets mixed with air and fuel mixture and getting burnt inside the combustion chamber and leaving the exhaust valve with blue smoke indicating that engine oil is getting burnt in the combustion chamber. The one and only solution for leaking piston rings is to open the full engine and rebuild the most of component including new piston rings, valve seals, gaskets etc. It’s a lengthy and expensive process so considering this overhauling engine vs replacing with another used engine is a very considerable thought. If you need more help, or need specific answer for any question then try the ‘Carnity Forum’ (http://carnity.com/) section or find car businesses near you with the Carnity ‘Business listing’ (http://carnity.com/business_listing) section.