Onan JC Service Manual

CRANKCASE BREATHER
The crankcase breather, located in the rear left corner
of the crankcase maintains a partial vacuum in the
crankcase during operation to control oil loss and
ventilate the crankcase. The older type includes
a
metal filter packed into the tube on the crankcase, a
rubber cap with flapper valve, and hose connecting
it
to the engine air horn. This breather is shown in
Figure
8.
To disassemble, remove the rubber cap from the
crankcase tube and pry the valve outof thecap. Wash
the valve in fuel at regular intervals and, if defective,
replace it. Also, pull the baffleout of the breathertube
and clean it. Install the valve with the perforated disk
toward the engine.
Beginning with Spec
T, the JC uses a PCV (Positive
Crankcase Ventilation) valve mounted under the
rocker boxes. See Figure 54.
'
Beginning with Spec S, the JB uses the new style
breather shown in Figure 55.The JC, prior to Spec T,
retains the older breather system without the valve.
Every
500 hours remove the PCV valve; wash in diesel
fuel or kerosene, and inspect for carbon residue. If the
valve appears to be unusually gummy,
it may have to
be disassembled (Figure
56) for cleaning. Replace-
ment with a new valve is preferable under these
conditions.
PCV VALVE
FIGURE 54. CRANKCASE BREATHER WITH
PCV VALVE
BREATHER HOSE
CAPAND 1
VALVE. 1
"0" RING
1
SCREEN
BAFFLE-
IER HOSE
LATOR
-HOSE CLAMP
CLAMP
i
INSULATOR
CRANKCASE
BREATHER
JB ENGINE
I (BEGIN SPEC.S)
BRE
TI
*e78
Remove hose clamp.breather hose,braather cap clamp
and Insulator halves to release breather cap and valve
assembly. Wash
cap and valveassembly ad the baffle
In sultable solvent and reinstall. .
FIGURE 55. CRANKCASE BREATHER
FIGURE
56- PCV VALVE
43
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Onan JC Specifications

General

Brand	Onan
Model	JC
Category	Engine
Language	English