TM 5-3810-300-24&P-3
OIL PUMP 4.1
with the .623" diameter shaft must be reamed to .625"
Inspect the pressure relief valve spring, relief valve and
.0005".
its seat in the pump body. If necessary, install new parts.
Assemble Oil Pump
Inspect the bushings in the pump body and cover or
scavenging pump body. If the bushings are worn
Refer to Fig. 3, and assemble the oil pump as follows:
excessively, replace the pump and cover or scavenging
pump body assemblies unless suitable boring equipment
1. If the drive gear (23) was removed from the drive
is available for finishing the new bushings. When
shaft (13), insert the Woodruff key (14) in the
installing new bushings, replace all of the bushings. The
keyway and apply a light coat of engine oil on the
bushings must be located and positioned as shown in
shaft. Start the shaft squarely into the bore of
Fig. 6. Also, the gear bore and the bushing bore in both
the gear and, as shown in Fig. 5, press the shaft
the pump body and cover or scavenging pump body
into the gear.
must be concentric within .001". The shaft-to-pump
body-bushing clearance with new parts is .0008" to
The gear must be 6-15/16" on 3 and 4 cylinder
.0025". The shaft-to-pump cover or scavenging pump
engines, or 6-15/32" on 6 cylinder engines, from
body bushing clearance with new parts is .0010" to
the keyway end of the drive shaft (Fig. 7).
.0027".
2. Press the dowel (88) into the pump body, if
CAUTION: When installing the spacer
removed.
between the oil pump body and the
scavenging pump body, be sure the
3. Place the idler gear support (82) in position
bleed hole is located on the discharge
against the forward end of the pump body (Fig.
side of the oil pump assembly. Refer to
3) and secure the support to the body with bolt
Fig. 3.
(86).
In an efficient oil pump, the gears should have a free-
4. Install the drive gear and shaft assembly in the
running fit (with no perceptible looseness) in the pump
pump body and slide the driven gear (22) onto
housing. The use of excessively worn gears will result in
the shaft (24).
low engine oil pressure which, in turn, may lead to
serious damage throughout the engine.
Fig. 6. Diameter and Location of Bushing in Oil Pump
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