Check the housing (7) for wear and scoring in the gear rotation area. Replace the housing if scoring
or a wear edge can be felt with the fingernail.
Check the bushings (9) in the housing (7). Replace a bushing if the bushing maximum inside
diameter is greater than 0.5016 inch (12.741 mm).
Check the depth of the gear bore in the housing (7). Replace the housing if the gear bore depth
exceeds 1.2485 inches (31.712 mm).
Check the diameter of the drive and idler shafts (11 and 12) for wear. Minimum diameter shall be
0.4998 inch (12.695 mm).
Check the gears (10 and 13) for worn, scored, cracked, or chipped teeth.
Check the width of the gears (10 and 13). The minimum width shall be 1.2483 inches (31.707 mm).
Temporarily install the gears (10 and 13) and drive and idler shafts (11 and 12) in the housing (7)
and measure the gear protrusion with a straight edge and feeler gage. The gear protrusion shall be -
0.0001 to +0.0005 inch (-0.003 to +0.013 mm). If the gear protrusion is unacceptable, it will be
necessary to replace the housing, select fit new gears, or replace both housing and gears to achieve
the correct protrusion.
Using a narrow 0.25 inch (6.4 mm) bladed feeler gage, or a wire gage, check the flank clearance
between the meshed gear (10 and 13) teeth. Replace gears if clearance is not 0.006 to 0.010 inch
(0.15 to 0.25 mm).
Check the protrusion of the drive shaft (11) from the housing (7). Drive shaft protrusion shall be
2.370 to 2.412 inches (60.2 to 61.3 mm).
If the checks made in steps (i) through (n), above, indicate the replacement of either the gears (10
and 13) or drive and idler shafts (11 or 12), proceed as follows:
If the gears (10 and 13) are to be reused, match-mark them so that they will be reinstalled on the
proper shaft, and in the same top-to-bottom position.
Remove the gears (10 and 13) using a 7/16 inch (11 mm) punch and an arbor press.
Press the drive and idler shafts (11 and 12) into the gears until the housing (7) end of each shaft
protrudes a distance of 0.680 to 0.690 inch (17.27 to 17.53 mm) from the gear face.
Reassemble. Lubricate all moving parts with lubricating oil MIL-L-9000, and reassemble the gear pump as
Apply a single wrap of Teflon tape MIL-T-27730, to the pipe plugs (6, Figure 6-8), and install them in
the housing (7). Tighten the plugs to 5 to 8 pound-feet (7 to 11 newton-meters).
Using driver 3375959, install a new pressure valve (14) in the cover (15) until it is even with the
cover face, or to within to 0.015 inch (038 mm) below the cover face.
Install the idler shaft and gear (2, Figure 6-9) in the housing cavity nearest the location notches (1)
and install the drive shaft and gear (3) in the other cavity.
Align the location notches (1), and install the cover (15, Figure 6-8) on the housing using a new
To avoid damage to the gear pump assembly (18), turn the drive shaft (11) while tightening the
capscrews (1). If binding occurs, disassemble and determine the cause before final
Install the capscrews (1), lockwashers (2), washers (3), and cross-tighten the capscrews in three
steps to 11 to 13 pound-feet (15 to 18 newton-meters).
Install the fuel inlet connection (4) and preformed packing (5) in the housing (7).