Onan NH User Manual

.
Apply a thin film of oil to the gasket. Spin element
down by hand until gasket just touches mounting pad
and then turn down an additonalV4-1/2 turn.
Do not
overtighten.
To disassemble, remove breather hose from cap and
valve assembly. Remove cap and valve assembly and
wash in a suitable solvent. Replace cap and valve if
balls do not move freely.
Pull baffle out and wash in
solvent. To allow free operation of the valve, screens
must be positioned as shown in Figure
8.
With oil in crankcase, start engine and check for leaks
around filter element. Retighten only as much as
necessary to eliminate leaks; do not overtighten.
CRANKCASE BREATHER
The crankcase breather prevents pressure from
building up in the crankcase.
It also prevents oil
contamination by removing moisture or gasoline
vapors and other harmful blow-by materials from the
crankcase. Thesevapors are routed to the carburetor
where they are mixed with incoming air and burned in
the combustion chamber. Asticky breathervalve can
cause leaks, high oil consumption, rough idle,
reduced engine power and a rapid formation of
sludge and varnish within the engine.
Crankcase Breather Service
This engine uses a crankcase breather valve for
maintaining crankcase vacuum. If the crankcase be-
comes pressurized as evidenced by oil leaks at the
seals, clean baffle and valve in a suitable solvent.
Clean or replace crankcase breather baff le periodically.
Besure baffle material doesn’t come apartand workinto
the manifold.
CAP AND VALVE HOSE CLAMP
PRESSURE LUBRICATION
All engines usean oil pumpto provideaconstantflow
of oil to theengine parts.TheoiI supply collects in the
oil base where
it is picked up by the oil pump pick-up
cup. A by-pass valve is used
to control oil pressure.
Drain oil before removing oil base and always use a
new gasket when replacing the oil base.
Oil Pump
The oil pump (Figure 9) is mounted behind the gear
cover and
is driven by the crankshaft gear. Inlet pipe
and screen assembly are attached directly to the
pump body. A discharge passage in pump cover
registers with a drilled passage in the crankcase.
Parallel passages distribute oil to the front main
bearing, rear main bearing, and pressure control
bypass valve.
OIL PUMP PICK-UP CUP
OIL PUMP ASSEMBLY
CRANKCASETURNED
ON LEFT SIDE
FIGURE 8. CRANKCASE BREATHER
FIGURE
9. OIL PUMP ASSEMBLY
13

Onan NH Specifications

General

Engine Model	NH
Cylinders	2
Fuel Type	Gasoline
Governor Type	Mechanical
Ignition System	Battery
Starter	Electric
Engine Type	4-cycle, air-cooled