Inspection and Repair.
(1) Measure diameter of bypass valve (3). If
measurement shows less than 0.3365-inch minimum
diameter, replace valve. Maximum diameter should not
Dry cleaning solvent P-D-680 Is toxic and
flammable. Always wear protective goggles
and gloves, and use only in a well-ventilated
(2) Measure free length of valve spring (3). If
area. Avoid contact with skin, eyes, and
free length is less than 2.3125-inch (+/- 0.0625-inch),
clothes, and DO NOT breathe vapors. DO
replace valve spring.
NOT use near open flame or excessive heat.
The solvent's flash point is 100F-138F
(3) Inspect valve spring tension under load
(38C-59C). If you become dizzy while
conditions. Using a compression scale, compress valve
using cleaning solvent, Immediately get fresh
spring to 1.1875-inch, and check the scale for 2.225 lb.
air and medical help. If solvent contacts eyes,
(+ /-0.110 lb.) compression.
Immediately wash your eyes with water and
get medical aid.
(4) Inspect plug (1) for evidence of worn or
damaged threads. Replace plug if defective.
(1) Clean gearcase gasket mating surface using
mating surface is cleaned free of all excess gasket
material. Wipe dry using a clean, lint-free cloth (item 24,
valve plunger (3), and install in bearing plate (4).
(2) Flush gearcase clean with diesel fuel
(item 14, Appendix E) and clean out the oil passages using
(2) Install recessed plug (1). Tighten plug
a fine cleaning wire.
Gear Cover Assembly
Particles blown by compressed air can be
dangerous. Ensure that air stream is directed
away from the user and other personnel in the
securing governor yoke (2) to the governor shaft (5), and
remove the yoke (2).
(3) Dry oil passages using clean, filtered com-
pressed air under moderate pressure of approximately
(2) Slide governor shaft free of the gearcase.
Inspection and Repair.
(1) Visually inspect gearcase for nicks or dents on
Do not remove pressed-in components such
the gasket mating surface. Inspect for cracks. Inspect bolt
as bearings, seals, and plugs unless there is
holes for damaged or excessively worn threads. Replace
evidence of damage, excessive wear or
gearcase if damaged.
(2) Inspect all components for evidence of
(3) Set the gearcase on wood supports.
excessive wear, scratches, and nicks. Replace defective
(4) Using the combination main and cam bearing
(3) Measure distance from end of roll pin to
mounting face of gearcase. The distance should be
0.781-inch. If necessary to replace pin, the pin should be
positioned with open end facing crankshaft seal.
drive out the needle bearing (7) and oil seal (6).
(1) Install thrust bearing (8, fig. 7-28) and ball
(6) Remove thrust bearing (8) and ball (9) if
(9), and press bearing into position.