Onan MJA Series Service Manual page 64

62 OIL SYSTEM
crankshaft 'gear. ':rv1ount the intake cup on the pump so it is parallel to
the b ottom of the crankcase.
3 .5.3 BY-PASS
VALVE
Located on the outside
of
the rear bearing plate, the valve COn ­
trols oil pressure by allowing excess oil to flow directly back to the oil
pan. Normally. the valve begins to open about 25 psi. It is non~adjust­
able and normally needs no maintenance.
To determine if high oil pressure is caused by the plunger sticking
c lased or low oil pressure by the plunger sticking open. clean and
inspect the valve.
1'0
remove the valve. unscrew the recessed plu.g in the rear bearing
plate. and
lift
out the spring and plunger assembly . Determine proper
valve ()peration by checking the spring and plunger against the following­
values:
Plunger Diameter .3365" to .3380"
Spring
Free Length 2-5/16 1/16"
Force at 1-3/16" 2.225.+.11 Ibs.
3.5.4 OIL LINES
The rocker box oil line should be flushed with fuel and the small holes
cleaned with fine wire at regular intervals. Clean out aU other oil
lines and drillings with compressed air whenever the is disas ­
sembled or overhauled. Reach the
, I- - - - - - - - - - - - - - - - ,
oil gauge passage
by
removing the
filte·r mounting plate.
AUexlernal oil lines. the rocker
bOx oil
line and the internal oil
line to the rear bearing are re­
placeable, if damaged.
'\
3.5.5GAUGE
\' The oil pressure gauge is located
'1
on the lower front conler of the
cylinder block. If it is faulty.
repl"aee it. Remove it with a
wrench, and screw in a new
gauge. Before rep laCing. check
for a clogged oil passage behind
the gauge.
FLUSH ROCKER BOX' OIL LINE WITH
FUEL AND CLEAN HOLES WITH FINE
WIRE
FIG 3. 5.C - ROCKER BOX
OIL
LINE