Onan MCCK - Page 10

The recommended Neoprene muffler (silencer) is an
Elasto-Muffle brand, size mark O.and two bushings,size
AB (fits 1-5/8” O.D.). A cast iron or stainless-steel
muffler is also available. Provide a recommended (or
equal) silencer and install it near the end of the wet
exhaust line.
Caution: Dry exhaust will damage the neoprene silencer.
WATER SUPPLY LIME
A continuous supply of cooling water is required. The
water pump inlet is a hose fitting for 1/2” I.D. hose
(see Fig.8). Use a section of non-collapsible hose near
the plant (or for the entire run) to absorb vibrations. The
inside diameter of the plumbing must be at least 1/2”.
Use Permatex or other pipe sealer on all pipe fittings
in supply line to pump. Normally, the pump should de¬
liver 3.5 gallons of cooling water per minute. Measure
the discharged water flow after thermostat opens, to
be sure the supply line is large enough. Reduce resis¬
tance on pipe runs longer than 5’ by using larger in¬
side diameter plumbing. To prove suction line is air¬
tight, see that no bubbles appear in discharged water.
An air teak reduces lubrication and shortens pump im¬
peller life. Install a strainer in the water suction line
inlet where it is accessible for cleaning.
Figure B. Water Pump Inlet Ho*e
WATER DISCHARGE LIME
The 1/2” I.D. water outlet hose fitting is on the ex¬
haust manifold next to the exhaust outlet (see Fig.7).
Use plumbing at least as large as the supply line. Use
a section of hose near the plant or the entire run. Con¬
nect the line to discharge the heated water into the ex¬
haust line several feet ahead of the Aqualift or neo¬
prene silencer. Make sure water cannot back flow into
the exhaust line. See Optional Heat Exchanger Cooling.
HEAT EXCHANGER COOLING (Optional)
Closed-type cooling systems are commonly referred to
as fresh water cooling or heat exchanger cooling. Water
circulated through the engine is called fresh water, hot
water , efc. Water circulated through the heat exchanger
only is called raw water, sea water, cold water, dis¬
charged water, etc. This system with an antifreeze cool¬
ant is recommended where freezing conditions exist, or
where the owner wants to prevent the possibility of
salt water problems.
Caution: Do not use the existing neoprene impeller
water pump in the hot water side of the cooling system
Heat or soluble oil (in many rust inhibitors and anti¬
freeze s) wifi damage the impeller. Instead, connect the
neoprene impeller pump on the cold water side. Use a
metal impelter, centrifugal-type water pump (Oberdorfer
1-GP, or equal) in the fresh water side. Drive it with a
belt from the plant power take-off (see Fig-9). _
FRESH WATER FROM
MANIFOLD
HEAT
EXCHANGER RAW WATER TO
EXHAUST
MANIFOLD
CYLINDER HEAD
DETAIL B
DRAIN
J
hTOHEAT EXCHANGER
PUMP
‘TO ENGINE PUMP
-EXHAUST OUTLET
GOVERNOR ADJUSTMENT
ENGINE PUMP
OIL PRESSURE
GAGE
LOW OIL PRESSURE
CUT-OFF SWITCH
BELT
HEAT EXCHANGER
PUMP
HIGH WATER
TEMPERATURE
SWITCH
DRAIN
HEAT
EXCHANGER
.t PUMP
RAW WATER
ENGINE PUMP
TO HEAT EXCHANGER
(INSIDE FITTING)
TO HEAT EXCHANGER
(REAR FITTING)
Figure 9. Cooling System Details
9