In a clean system, the maximum pump inlet restriction must not exceed 6 inches of mercury. At normal operating
speeds (1800-2800 rpm), the fuel pressure is 45 to 70 psi (310 to 483 kPa). Change the fuel filter elements whenever
the inlet restriction (suction ) at the fuel pump reaches 12 inches of mercury at normal operating speeds and whenever
the fuel pressure at the inlet manifold falls to 45 psi (310 kPa).
Remove the dirty oil and sludge from the oil bath-type air cleaner cups and center tubes every 8 hours or less if operating
conditions warrant. Wash the cups and elements in clean fuel oil and refill the cups to the level mark with the same
grade of heavy duty oil as used in the engine. The frequency of servicing may be varied to suit local dust conditions.
It is recommended that the body and fixed element in the heavy-duty oil bath type air cleaner be serviced every 500
hours, 15,000 miles or as conditions warrant.
Clean or replace the element in the dry-type air cleaner when the restriction indicator instrument indicates high restriction
or when a water manometer reading at the air inlet housing indicates the maximum allowable air inlet restriction (refer to
the Air Inlet Restriction chart in the Trouble Shooting section). Refer to the instructions in the Air System section for
servicing the dry-type air cleaner.
With the engine running, check for flow of air from the air
box drain tubes every 1,000 hours or 30,000 miles. If the
tubes are clogged, remove, clean and reinstall the tubes.
The air box drain tubes should be cleaned periodically
even though a clogged condition is not apparent. If the
engine is equipped with an air box drain tank, drain the
sediment periodically. If the engine is equipped with an air
box drain check valve, replace the valve every 500 hours
or 15,000 miles.
Clean the externally mounted crankcase breather
assemblies every 1,000 hours or 30,000 miles. This
cleaning period may be reduced or lengthened according to
severity of service. Clean the internally mounted breather
pads at time of engine overhaul, or sooner if excessive