Understanding Engine Blow-by Pressure 

What is blow-by pressure? What does blow-by mean in an engine? Blow-by pressure is the allowable pressure within the crankcase. This blow-by pressure is permissible because it originates from engine compression leaks in the combustion chamber. As the piston moves from top dead center (TDC) to bottom dead center (BDC) during the compression process, this pressure leaks through the gap between the piston rings and the cylinder liner. So, the blow-by pressure will increase over time. 

blowby-engine

If there is damage to the piston ring or excessive wear on the cylinder liner, the blow by pressure number will increase. The units used when measuring blow by pressure are mmAq or Kpa. The blow-by engine pressure will be released (out) to the outside air, through the engine breather which will be continued to the outside air through the breather hose. 

If the engine blow-by pressure becomes greater, the oil will come out through the engine breather hose and the engine blow-by pressure will also rise into the combustion chamber (cumbustion chamber) along with carrying engine oil with it or what is called oil up. The engine breather hose will also spray engine oil if you overfill the engine oil (above the High level on the dipstick). 

Signs of High Engine Blow-by Pressure 

Engine blow-by pressure measurements are primarily performed to assess the wear level (condition) of the liner and piston rings. To confirm engine blow-by pressure (wear on the liner and piston rings), the following steps are taken: 

• Engine blow-by pressure exceeds the standard or permissible level. 
• Blow-by color tends to be bluish, indicating oil burning. 
• High oil consumption.
• PAP results (silicon, dust, metal, wear). 
• Blow-by pressure trend analysis.

Causes of Excessive Blow-by Pressure 

• Excessive wear on the liner and piston rings. 
• Leaks in the valve steam and guide (intake boost pressure, exhaust gas). 
• Leaks through the push rod sleeve.

Lokasi: Indonesia

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