Causes of blue smoke from the exhaust!

Recently updated on January 27, 2022 at 10:20 am

What could be the causes of blue smoke from the exhaust? The exhaust gases from the combustion engine are made up of Nitrogen (N2), Carbon Dioxide (CO₂) and Steam (H₂O). Usually exhaust gases colorless. However, if the smoke is blue, it indicates that either the fuel or the engine oil is not being burned as it should be. It is important, when the smoke is blue. It can only affect the time after starting or when acceleration restrict. Info: The bluish discoloration is usually not a problem for vehicles with Otto/petrol engines if it only occurs after a cold start. The smoke is then due to the so-called cold start enrichment blue.

Can you continue?

If the car has warmed up and bluish smoke is still coming out, or if the vehicle has a diesel engine where cold start enrichment cannot be the cause, then a workshop should be consulted. Depending on where exactly the problem lies, the cause can be costly in the long run engine failure entail.

What causes the blue exhaust fumes?

• Defective or worn piston rings. In combustion engines there are pistons surrounded by a piston ring. One of their tasks is to seal the combustion chamber from the crankcase and they also dissipate combustion heat. The piston rings are also responsible for wiping the oil off the cylinder running surface. However, piston rings can wear out, coke or even break. If the piston rings can no longer work properly due to wear or defects, oil can get into the combustion chamber. There it is burned, which causes the bluish smoke.

• Defective valve stem seals. They are also called valve stem seals and are located on the individual valves. Their job is to keep the combustion chamber sealed against the cylinder head. As the valve stem seals are subjected to heavy loads and high temperatures, they can age brittle will. Brittle valve stem seals can then no longer seal properly. As a result, oil gets into the combustion chamber and is burned, resulting in blue exhaust gases. The cylinder head must be removed to determine if the valve stem seals are the cause of the blue smoke. Once the cause has been found, the valve stem seals are replaced with new ones.

Tip: more information, in case of "black smoke"

• The cylinder head gasket/cylinder head is defective. The cylinder head is the top end of the engine and sits directly on the engine block. Gasoline engines, for example, have inlet and outlet ports, valve control and spark plugs in the cylinder head. If there are leaks in the area of ​​the cylinder head or the cylinder head gasket, the oil can get into the combustion chamber and burn there. This can result in bluish exhaust fumes. If part of the oil burns, the oil in the engine will become less and less, which can have a negative effect on lubrication. Poor lubrication, in turn, can result in expensive engine damage. So you should go to a workshop as soon as possible.

• A defective turbocharger. Diesel and petrol engines almost always have so-called exhaust gas turbochargers, or turbo for short. A turbo increases the efficiency and performance of the engine by increasing the air supply. If there is a defect in the turbo, it can happen that engine oil gets into the intake tract. From there, the oil can get into the combustion chamber, where it burns and the bluish exhaust gases are produced. As the damage progresses, the smoke can go from bluish to dense, pass white smoke. If the cause is the turbocharger, it must be repaired or replaced. It can be exchanged for a new or replacement turbo.

What other causes are there for bluish exhaust fumes?

There are other causes besides those already mentioned additional reasons, which can cause blue exhaust gases, such as

• a defect to the Injectors or injectors
• Leak in the oil circuit
• a defect on Catalyst
• Intermittent combustion, as with defective ones spark or ignition coils, should also have one uneven engine running trigger

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