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Have you ever wondered what makes an engine smoke blue? What components are the key causes? What can you do to reduce your risk of blue smoke? Blue smoke is seen in the exhaust gases as burnt lubricating oil and can originate in several areas within the engine and usually means trouble.

The first area where blue smoke may appear is from within the cylinder head, worn valves or worn valve guide seals may be causing excess oil to seep into the intake stroke of the engine. Valve guide seals can break down due to irregular oil and/or filter changes. It is also advisable to replace valve springs, collets and seats, or the problem might be in the cylinder block, wear on pistons and piston rings can result in blue smoke at all speeds, loads and temperatures.

Considering on average that pistons travel 34 kmph and change direction up to 26,400 times an hour, the piston rings are susceptible to gumming without proper maintenance, this causes a loss of combustion pressure and power. In the generator application, prolonged underloading the engine (below 35% of rating) will eventually result in glazing of the cylinder bores (Wet-Stacking), unburnt fuel in the exhaust system and coking up of the cylinder head/valves/ports.

If acted upon early this can be reversed with a loadtest around full rating for a few hours. If your engine is still producing blue smoke there is one more potential culprit, gummed up or worn seals are an open invitation for oil to seep into the turbocharger, remember engine maintenance is important, using the correct oil is crucial to overall performance, don’t skip scheduled service, used genuine manufacturers parts to keep your engine at its best and use the Manufacturers distributor network for all your maintenance and repair needs, because blue shouldn’t make you see red!

See a short animation on the subject here

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