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Checking Fan Belt and Tension
Fan belt and belt tension should be checked daily
or before each use. Fan belt should not be cracked,
damaged, or exhibit excessive wear. Proper tension is
12.7 mm (3/8 - 1/2 in.) belt defl ection per side under
10 lbs. applied tension.
If belt is cracked, damaged, or is worn that relocation of
pulley shims cannot establish proper belt tension, belt
should be replaced. Use only Kohler Part No. 66 203
02-S belt. DO NOT use a substitute belt.
For a new belt, assemble lower pulley with all three
shims between pulley halves. For a used/original belt
being reinstalled, assemble with two or one shim(s)
between pulley halves and remaining shim(s) on
outside (front) of outer pulley half. Check belt tension as
described above.
When proper tension is obtained, individually remove
each capscrew of lower pulley, apply Loctite
threads, and reinstall. Torque each capscrew in a criss-
cross sequence to 24.3 N·m (215 in. lb.).
Hoses and Tubes
Hoses and tubes are used to connect components
within cooling system. To guard against coolant loss and
hose failure, hoses, tubes and their connections should
be checked regularly for leaks or damage. Loss of
coolant can result in serious engine damage. Over time,
engine vibration can aff ect hose/joint connections, and
hoses themselves can be aff ected by heat and coolant.
Swelling, hardening, and/or deterioration can occur
depending on operating environment. Deterioration
usually takes place more rapidly from inside, making
outside inspections incomplete and not always
dependable. Regular outside inspection and careful
inside inspection whenever connections are opened, can
minimize a possible in-service problem.
Use new clamps whenever a hose is replaced or a joint
connection is opened. When making hose connections,
a light coating of rubber lubricant will make assembly
easier.
Thermostat Testing and Servicing
Temperature Sensor Details
A
Temperature Sensor
Thermostat is mounted in intake manifold, beneath
thermostat housing. It controls rapid warm-up and
operating temperature of engine. If a problem is
encountered which is thought to be fault of thermostat,
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it can be checked to determine its operating condition.
Before removing and testing thermostat, make sure all
other possible causes such as debris accumulation/
obstruction, leaks, belt or fan failure, coolant level,
and damaged components are eliminated as possible
causes.
To Test
Remove thermostat from system. Hang or suspend
thermostat by its frame in a container of water, so
thermostat does not touch bottom of container. Heat
water and measure temperature (an oven thermometer
can be used). Spring-loaded valve of thermostat should
begin to open at 79.4°C (175°F), and can be completely
open at 90°C (195°F). If valve opens at a temperature
more than 10 degrees below specifi ed opening or
fails to open at a temperature 10 to 15 degrees above
specifi ed opening, thermostat should be replaced. If
valve in thermostat can be moved or pushed off its
seat with a slight eff ort when thermostat is cold, unit
may be considered defective and should be replaced.
Thermostat should be replaced if operation is found to
be questionable or faulty.
Installation
1. Thoroughly clean sealing surfaces of intake manifold
and thermostat housing with an aerosol gasket
remover. Make sure sealing surfaces are clean and
free of nicks or damage. Make sure notch in intake
manifold is clean.
2. Install a new thermostat into intake manifold, so
larger spring end is down into well of intake
manifold. Position a new thermostat gasket on intake
manifold.
3. Install thermostat housing onto intake manifold.
4. Install and torque screws to 9.9 N·m (88 in. lb.).
5. Reconnect radiator hose and secure with hose
clamp, if separated previously.
High Temperature Sensor
A high temperature sensor may be mounted in intake
manifold and is used to activate a warning light, audible
alarm, or kill engine (depending on application), if safe
operating temperature is exceeded. Sensor is a normally
open switch which completes a circuit, when coolant
temperature reaches rated temperature limit of switch.
For these engines temperature sensor limit is 123.8°C
(255°F).
If warning device activates, or engine kills, indicating an
excessive operating temperature, check following:
1. Make sure fan belt is in good condition and properly
tensioned.
2. Make sure cooling fan is properly secured, not
broken, damaged, or missing blades.
3. Make sure all air intake and cooling surfaces are
clean and free of debris accumulation.
4. After engine has suffi ciently cooled, check coolant
level in system to make sure it is not low, or
improperly mixed.
5. Check cooling system for leaks.
Cooling System
65
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