Gear Cover
Oil
Seal:
Replace the oil seal if damaged
or worn. Drive the
oil
seal out from inside the gear
cover. Lay the cover on a board
so
the seal boss
is
supported. Using an oil seal driver, insert the newseal
from the inside with rubber lip toward outside of gear
cover (open side of seal inward) and driveit flush with
the outside surface. During gear cover installation,
use the driver to protect the
oil
seal. See Figure 53.
1
WHEN GOVERNOR
IS
PROPERLY ASSEMBLED
THE DIMENSION SHOWN
ON
DRAWING WILL BE
AS
INDICATED.-
Assembly, Gear Cover:
I
1.
Work governorshaft to check for binding and see
that the governor shaft end-thrust ball is in place,
Figure 52.
2.
Turn governor yoke
so
smooth side is toward
governor cup.
3. Turn governor cup
so
stop pin
in
gear cover will fit
into one of the holes in the cup surface (Figure
52). Measure distance from end of stop pin to
mounting face of cover. It should be
25/32
inch
(1
9.844 mm). If it is not, replace pin. Pin should be
positioned with open end facing crankshaft seal.
4. Coat oil seal lip with oil or grease. Apply a piece of
masking tape over the crankshaft keyway to pro-
tect seal and install gear cover.Tighten mounting
screws to
15
to
20
foot-pounds
(20
to
27
Nm).
Before tightening screws, be sure the stop pin is
in governor hole. See Figure 53.
GEAR
COVER
INSTALLOIL SEAL
FLUSH
WITH
THIS
SURFACE
OIL SEAL
THIS SURFACE MUST
BE
CLEAN
BEFORE
INSTALLING SEAL
FIGURE
53.
GEAR COVER
OIL
SEAL
GOVERNOR CUP
To remove the governor cup, remove the snap ring
from the camshaft center pin and slide the cup off. Be
sure to catch the five (some models have ten) flyballs
that will fall out when the cup is removed. Figure
54
shows the governor cup.
CENTER
P
SNAP
GOVERNOR
U
FIGURE
54.
GOVERNOR
CUP
Repair:
Replace any flyballs that have flat spots or
grooves. The flyball spacer is attached to the cam-
shaft gear with three flathead screws. Check to see
that the spacer screws are tight. Replace the cup if the
race surface is grooved or rough. The governor cup
must be afree spinning fit on the camshaft center pin,
but should be replaced
if
excessively loose or wobbly.
Thecamshaft center pin extends out 3/4 inch (19 mm)
from the end of the camshaft. This distance provides
an in-and-out travel distance of 7/32 inch
(5.6
mm)
for the governor cup, as illustrated. Hold the cup
against the flyballs when measuring. The camshaft
center pin cannot be pulled outward or removed
without damage. If the center pin extends out too far,
the cup will not hold the flyballs properly.
If
the dis-
tance is less than 7/32 inch
(5.6
mm), (the engine will
race, especially at no load) remove the center pin and
press in a new pin.
Installation:
To install the governor assembly, tip the
front of the unit upward. Set the flyballs in their
recesses (space five balls in every other slot) and
position the governor cup on its shaft. Finally, brush
with heavy grease and install the snap ring on the
center pin.
PISTONS, RINGS, CONNECTING RODS
Onan diesel engines use cam-ground aluminum
pistons. Each piston is tapered and fitted with three
compression rings and an oil control ring. Full-
floating piston pins connect the piston
to
its connec-
ting rod. The pins are held in place with a snap ring at
each end. The lower end of each connecting rod
contains half-shell precision bearings and the upper
end
,
s
e
m
i
-f
i
n ish ed bush
i
n
g
s.
Some engines are fitted with
0.005
inch
(0.127
mm) oversize
pistons at the factory. These engines are marked with an E
following the engine serial number. Use
0.005
inch
(0.127
mm)
oversize rings for these pistons.
53
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