Cooling System - Kohler Aegis ELH775 Service Manual

Hot liquid can cause severe burns.
Do not loosen radiator cap while engine is
operating or warm to touch.
When it is necessary to open cooling system at radiator
cap, shut off engine and remove fi ller cap only when cool
enough to touch with bare hands. Slowly loosen cap to
fi rst stop to relieve pressure before removing completely.
This section covers operation and servicing of liquid

cooling system.

Cooling System Components
Cooling system consists of these following components:
● Radiator with removable screen
● Hoses
● Coolant Pump and Belt
● Thermostat
● Intake Manifold with Thermostat Housing
● Radiator Cap
● Cooling Fan, Belt, and Drive Pulleys
● Overfl ow Reservoir
● Crankcase and Heads with Integral Cooling Passages
Operation
Engine coolant is pumped through cooling system by
a pump, belt-driven off camshaft. Coolant coming out
of pump is divided, and moves simultaneously through
separate circuits within each head and corresponding
sides of crankcase. As coolant moves through these
passages, it absorbs heat from engine parts. After
traveling through engine, coolant from two separate
circuits merges and moves through intake manifold to
lower side of thermostat. During warm-up, thermostat is
closed, preventing circulation through radiator. Coolant
circulates through engine only and is returned to pump
via bypass hose. When engine heat brings coolant up to
a temperature of 79.4°C (175°F), thermostat will begin
to open, allowing coolant to circulate through upper hose
to radiator. Thermostat is completely open at 90.5°C
(195°F) allowing full coolant fl ow through radiator, where
it is cooled. After getting cooled in radiator, coolant
is drawn into pump through lower radiator hose and
circulation starts all over again. A cooling fan, driven off
fl ywheel by a belt, draws ambient air through radiator, to
maintain cooling process.
Coolant will provide protection from -37°C (-34°F) to
108°C (226°F). For protection and use outside indicated
temperature limits, follow antifreeze manufacturer's
instructions on container, but do not exceed 70%
antifreeze.
DO NOT use antifreeze with stop-leak additive(s), or put
any other additives in cooling system.
66 690 14 Rev. A
WARNING
KohlerEngines.com
Liquid coolant can get extremely hot from operation.
Turning radiator cap when engine is hot can allow steam
and scalding liquid to blow out and burn you severely. Shut
off machine. Only remove radiator cap when cool enough
to touch with bare hands. Slowly loosen cap to fi rst stop to
relieve pressure before removing completely.
Cooling System Maintenance and Service
Maintenance
Maintaining correct coolant level, cleaning any debris
accumulation from radiator surfaces, and insuring all
parts are in proper operating condition, is critical to
ensuring long life, proper system performance and
preventing overheating. To ensure proper air circulation,
make sure radiator, cooling fan, drive belt, pulleys,
cooling fi ns, and external surfaces of engine are kept
clean and in good condition at all times. Check coolant
level and clean away any debris accumulation daily or
before each use. Simultaneously inspect hoses and all
system connections for signs of leakage. Make sure
cooling fan is not cracked or missing any blades. Check
that fan belt and two drive pulleys, are in good condition
and proper belt tension is present.
Service
Lift screen vertically to remove for cleaning/servicing.
Clean screen and cooling fi ns of radiator with a soft
brush or blow out using clean compressed air. To avoid
damage to screen and cooling fi ns, do not use a high
pressure washer to clean.
Checking Coolant Level
Overfl ow Reservoir Details
A Full
NOTE: Do not operate engine without coolant in system.
Do not remove radiator cap when hot. Engine
coolant is hot and under pressure and can cause
severe burns. To prevent engine overheating
and damage, do not exceed more than 70%
antifreeze in cooling system.
Coolant level should be checked at overfl ow reservoir,
located behind radiator on fan shroud.
1. Check coolant level within overfl ow reservoir.
Coolant level should be between FULL and ADD
marks on reservoir. Do not operate engine with
coolant level below ADD mark.
Cooling System
A
B
B Add
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