Closed crankcase ventilation system

A closed crankcase ventilation system, comprising:

• an inlet adapted to receive blow-by gases from an engine crankcase;
• an outlet adapted to supply the blow-by gases to an air inlet of the engine;
• a pop off valve having an input and an output, wherein the input is coupled to the inlet and the output is operative to vent the blow-by gas outside the system when a crankcase pressure exceeds a first predetermined value;
• and
• a coalescer/filter coupled between the inlet and the outlet for flow of blow-by gases therethrough a low pressure filter:
• and
• a bypass valve coupled to the low pressure filter and to the coalescer/filter;
• wherein the bypass valve has a first position which causes the blow-by gases to pass from the inlet, through the low pressure filter and into the outlet;
• and
• wherein the bypass valve has a second position which causes the blow-by gases to pass from the inlet, through the coalescer/filter and into the outlet.

A closed crankcase ventilation system, comprising:

• an inlet adapted to receive blow-by gases from an engine crankcase;
• an outlet adapted to supply the blow-by gases to an air inlet of the engine;
• a low pressure filter;
• a coalescer/filter;
• a bypass valve coupled to the low pressure filter and to the coalescer/filter;
• wherein the bypass valve has a first position which causes the blow-by gases to pass from the inlet, through the low pressure filter and into the outlet;
• wherein the bypass valve has a second position which causes the blow-by gases to pass from the inlet, through the coalescer/filter and into the outlet;
• a vacuum limiting valve coupled between the inlet and the outlet and operative to discontinue blow-by gas flow from the inlet to the outlet when a crankcase pressure falls below a first predetermined value;
• and
• a pop off valve coupled to the inlet and operative to vent the blow-by gas outside the system when the crankcase pressure exceeds a second predetermined value.