COOLING SYSTEM MAINTENANCE
The cooling system including the block and radiator
should be cleaned and flushed at least once a year.
This is especially true in cold weather conditions or
when preparing unit for extended storage (over
30
days or more)!
The cooling system can work efficiently only when it is
clean. Scale and rust in the cooling system slow down
heat absorption and restrict water flow.
The thermostat is calibrated to open at 15OoFf2OF. It
should be checked also.
An appropriate anti-freeze mixture should be used in
colder climates as necessary.
Corrosion inhibitors reduce the formation of rust in a
cooling system. Corrosion protection can best be
provided in winter by using anti-freeze containing the
inhibitor.
Water filters should be used in areas where the water
is extremely hard and rust inhibitors cannot protect
the cooling system from the formation of rust and
scale.
Keep the radiator clean to provide maximum cooling.
Remove all dirt, lint, etc. Keep the radiator cap closed
during operation.
Check the fan belt tension periodically. For proper
operation of the water pump, the fan belt should be
tight enough to prevent slipping.
Check the water pump for wear periodically. Loosen
the fan belt and move the fan and water pump pulley
back and forth.
If
wear is excessive, replace the
bearing.
DRAINING COOLING SYSTEM
Whenever draining the cooling system for changing
anti-freeze solution or for out-of-service protection
when only water is used, be sure to open all drains
and hose connections where water could be trapped.
The following drain plugs must be removed to allow
complete flushing of the cooling system.
Radiator:
One petcock lower right front corner.
Engine Block:
One drain plug left front near water
pump.
Water Pumps:
One drain plug under cover or by
loosening cover.
If
an optional water jacket tank heater is used it should be drained
and flushed also. The lower hose must be disconnected at the tank
heater. There is no drain plug.
‘
Further information concerning the location and part
numbers for the various drain plugs throughout the
unit is shown in the
Parts
Catalog.
Onan recommends the use of clean ethylene glycol
anti-freeze solutions in closed cooling systems dur-
ing normal operation and storage periods. Be sure
anti-freeze solution will protect the cooling system
during the coldest winter weather.
FLUSHING SYSTEM
Flush the system at least once a year and more often
if
operation indicates clogged passages or overheating.
To flush the system:
1.
Drain the radiator, cylinder block and exhaust
manifold.
2. Remove the inlet and outlet hoses between the
engine and radiator.
3.
Close all drain plugs and attach the flushing gun
nozzle to the water outlet, as near the exhaust
manifold as practical. Restrict the normal inlet line
opening until the system fills with water, then
apply air pressure gradually. Repeat the process
until the water from the cylinder block flows clean.
4.
Remove flushing gun.
5.
Reinstall thermostats, hoses and drain plugs and
refill the system with the proper coolant.
6.
When flushing is completed, check the system
thoroughly for any leaks uncovered by the clean-
ing operations.
BLEEDING AIR FROM COOLING SYSTEM
Air must be bled from the cooling system for proper
operation.
If
your engine is not equipped with a vent
plug in the water pump housing, install a
3/8”
pipe
plug in the top of the housing. Allow engine to cool
and bleed as follows:
1.
Fill radiator with
50-50
mix of ethyleneglycol anti-
freeze and water.
2.
Remove plug or sender from water manifold on
top of engine to vent trapped air (Figure 7b).
Replace plug or sender when water emerges from
hole.
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