AIR BOX DRAINS
During normal engine operation, water vapor from the air charge, as well as a slight amount of fuel and
lubricating oil fumes, condenses and settles on the bottom of the air box. This condensation is removed by the
air box pressure through air box drain tubes mounted on the sides of the cylinder block.
The air box drains must be kept open at all times, otherwise water and oil that may accumulate will be drawn
into the cylinders.
One drain tube is used on an in-line engine (Fig. 1) at the rear end of the cylinder block.
A periodic check for air flow from the air box drain tubes should be made (refer to Preventive Maintenance)
Figure 1. Air Box Drain Tube Mounting (In-Line Engines)