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TRUCK SERVICE MANUAL
TM 5-4210-230-14&P-1
COOLING SYSTEM
EFFECTS OF COOLING SYSTEM NEGLECT
A neglected cooling system can lead to inefficient engine
operation, either directly or indirectly. Most of the problems
may be traced to overheating; however, an engine that is
running too cold can be just as troublesome.
Overheating may lead to troubles such as the following:
1. Burned valves.
2. Pinging or knocking.
3. Vapor lock.
4. Poor lubrication-increased engine wear.
5. Sticking valve and valve lifters.
6. Short spark plug life.
7. Engine hot spots.
8. Need for higher octane fuel.
Overcooling often results in the following:
1. Excessive fuel consumption.
2. Sludge formation in crankcase.
3. Corrosive acids found in crankcase.
COOLING SYSTEM MAINTENANCE
A. COOLING SYSTEM INHIBITORS
1.
Systems With Coolant Filters
Properly inhibited coolant will keep the engine free of
rust, scale deposits and corrosion. New vehicles are
delivered with IH anti-freeze and coolant and may be
equipped with a coolant filter. The coolant filter should
be changed according to the intervals contained in the
respective Operator's Manuals.
2.
Systems Without Coolant Filters
Vehicles without a cooling system must have the
coolant inhibitors replenished by adding IH cooling
conditioner. The conditioner should be added as
recommended in the respective Operator's Manuals.
A complete drain, flush and refill with water and
conditioner,
or
IH
anti-freeze
and
coolant
is
recommended once a year. This includes all vehicles
irregardless of yearly mileage.
If the cooling system has been permitted to become
rusty or dirty, use IH cooling system cleaner and
neutralizer
carefully
following
cleaning
recommendations on the container.
3.
Coolant Testing for Inhibitor Strength
Coolant should be checked for reserve alkalinity using
test strips available from various sources at each oil
change. Indication of a low alkalinity condition
necessitates a need to add IH cooling conditioner,
change cooling filter or to drain contaminated coolant.
B. DRAINING THE COOLING SYSTEM
When the cooling system of a vehicle is drained, some
coolant is likely to be retained in the pockets of the cooling
system. This is especially true in engines equipped with oil
coolers or heat exchangers having a tube bundle. If only water
with cooling conditioner is used and these engines are drained
and then exposed to freezing temperatures, the water
conditioner will freeze and possibly rupture one or more of the
tubes. The resulting leak will be difficult to locate and could
eventually damage the engine by mixing the cooling with the
engine oil.
To avoid damage, take one or the following precautions
when draining for shipment or storage in freezing temperature:
a.
Fill the cooling system with antifreeze solution,
operate engine until the thermostat opens or
until circulation is observed in the radiator
circuit, then drain.
b.
If conditioned water is used, drain the engine,
then blow out the residual solution in the cooler
tubes with compressed air through one of the
drain cocks or plugs on the cooler.
C. CLEANING THE COOLING SYSTEM
1.
Coolant
shut-off
cocks
to
heaters
and
other
accessories should be open to allow complete
circulation during cleaning, flushing and draining. Run
the engine with the radiator covered if necessary until
temperature is up to operating range 72-84 degs. C
(160-180 degs. F). Stop engine, remove radiator cap
carefully (if so equipped) and drain system by opening
drain cocks on radiator and crankcase.
2.
Allow engine to cool, close drain cocks and pour
cleaning
compound
into
radiator
according
to
directions. Fill system with water.
3.
Place a clean drain pan to catch over-flow and use to
maintain level in radiator.
CTS-2019P Page 8
PRINTED IN UNITED STATES OF A MERICA
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