Diesel Models
The diesel models use a closed crankcase ventilation system which prevents blow-by gases from entering the atmosphere. A crankcase emission control valve keeps crankcase pressure constant.
During part throttle engine operation, blow-by gas pressure opens the control valve allowing gases to flow through a connecting hose to intake manifold for burning. When the throttle is closed, the control valve reduces flow rate so engine will not draw in dust and air around crankshaft oil seal.