Kohler LH630-775 Service Manual page 87

Section 7
Cooling System
Thermostat
Figure 7-12. Intake/Thermostat.
To Test
Remove the thermostat from the system. Hang or
suspend the thermostat by its frame in a container of
water, so the thermostat does not touch the bottom of
the container. Heat the water and measure the
temperature (an oven thermometer can be used). The
spring-loaded valve of the thermostat should begin to
open at 79.4°C (175°F), and can be completely open at
90°C (195°F). If the valve opens at a temperature more
than 10 degrees below the specified opening or fails to
open at a temperature 10 to 15 degrees above the
specified opening, the thermostat should be replaced.
If the valve in the thermostat can be moved or pushed
off its seat with a slight effort when the thermostat is
cold, the unit may be considered defective and should
be replaced. The thermostat should be replaced if
operation is found to be questionable or faulty.
Installation
1. Thoroughly clean the sealing surfaces of the
intake manifold and thermostat housing with an
aerosol gasket remover. Make sure the sealing
surfaces are clean and free of nicks or damage.
Make sure the notch in the intake manifold is
clean.
2. Install a new thermostat into the intake
manifold, so the larger spring end is down into
the well of the intake manifold. Position a new
thermostat gasket on the intake manifold.
3. Install the thermostat housing onto the intake
manifold.
4. Install and torque the two hex flange screws to
9.9 N·m (88 in. lb.).
7.6
Intake
Manifold
5. Reconnect the radiator hose and secure with the
hose clamp, if separated previously.
High Temperature Sensor
A high temperature sensor may be mounted in the
intake manifold and is used to activate a warning
light, audible alarm, or kill the engine (depending on
the application), if the safe operating temperature is
exceeded. The sensor is a ''normally open'' switch
which completes a circuit, when the coolant
temperature reaches the rated temperature limit of
the switch. For these engines the temperature sensor
limit is 123.8°C (255°F).
Temperature Sensor
Audible Alarm
Figure 7-13. Warning Devices.
If the warning device activates, or the engine kills,
indicating an excessive operating temperature, check
the 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.