TM 10-4320-307-24
4-10
LUBE OIL PUMP ASSEMBLY REPAIR (CONT).
NOTE
If plug depth is within specifications and engine oil
pressure is out of specifications, remove and
inspect bypass valve (14).
15. Using depth micrometer (13), measure the installed
depth of the bypass valve (14) retainer plug (15),
located in pump body (1). If plug depth is less than
0.255 inch (6.48 mm) use pressure valve fixture to
install it to depth of 0.255 to 0.275 inch (6.48 to 6.98
mm).
Hold in on retaining plug to keep it from spring
out of bore due to spring compression. Failure
to do this may cause personal injury.
16. If required, use light duty puller kit to remove retaining
plug (15).
17. Remove valve disc (16), washer (17), and bypass
valve spring (18).
18. Inspect all parts for damage.
19. Inspect spring (18) for damaged or broken coils.
20. Using valve spring tester, compress bypass valve
spring (18) to a height of 1.145 inches (29.0 mm). The
force required to compress the spring to this height
must be 59 to 72 lbs (260 to 320 N). Replace spring if it
does not conform to this standard.
21. Measure bypass valve seat depth in pump body (1).
Maximum allowable depth is 1.840 inches (46.73 mm).
If depth exceeds this limit, replace pump body.
22. Measure outside diameter of drive shaft and idler shaft.
Replace shaft if outside diameter is under 0.6145 inch
(15.608 mm).
23. Measure inside diameter of bushings. Replace bushing
if inside diameter exceeds 0.6185 inch (15.710 mm).
Use bushing mandrel and arbor press to remove
bushing.
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