This is the symptoms of blow-by found in a car. Simply put, the wear on the piston rings and cylinder liner allowed the gas mixtures pass the piston into crankcase. The gases plus the unburned fuel may also dilute the engine oil and thus impacting the lubrication of the engine. The ineffective of the compression will resulting the inefficient combustion, less horsepower produced and loss of fuel economy. It may cause the crankshaft and camshaft seal give way resulting from the overpressure crankcase. Engineering lessons demonstrates the solution
for the over pressure crankcase into providing the crankcase breather and
positive crankcase ventilation (PCV) normally discovered in automotive cars. The
defects on the piston sealing towards liner wall to be fixed in first place to avoid greater damage. The breather or ventilation however unable to sustain to the extent of larger amount of blow-by gases due to greater gaps between cylinder liner and piston.
