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Cooling System
6. Check thermostat, and pressure test radiator cap.
7. Make sure water pump and drive belt are
operational.
8. Check and inspect wiring from sensor for shorting or
damage.
If none of those are found to be cause do following:
1. Drain coolant from system, so level is lower than
installed position of temperature sensor.
2. Remove and replace temperature sensor. Use pipe
sealant with Tefl on
on threads.
®
Cooling System Leakage Test
A pressure test of cooling system can be performed as a
relatively simple means of determining whether cooling
system may contain a leak. A pump/pressure type
cooling system tester with appropriate 45 mm adapter
may be used to check cooling system and radiator cap.
Test Instructions
1. With engine cool, carefully remove radiator cap (see
Pressure Radiator Cap). Make sure all parts of cap
and adapter are clean. Install cap on corresponding
adapter and make sure it is completely seated.
Install adapter onto tester and lock in place.
2. Pressurize tester to 15 psi.
3. Observe indicated pressure. It should hold steady
and not decrease or leak down.
If leakage is detected, cap should be replaced. If
tester pressure is increased to 16 psi, or above, cap
should then bleed off this excess pressure.
4. Install and lock system adapter and tester onto neck
of cooling system. Pressurize tester to 14-15 psi.
5. Observe system pressure on gauge.
Gauge Needle Holds Steady
If gauge needle holds steady, there should be no serious
leaks in system. It is however, recommended that all
connections be checked for overall condition anyway,
using a fl ashlight.
Gauge Needle Drops Slowly
If gauge needle drops slowly it indicates presence of
a small leak or seepage. Check all components and
connections for signs of leakage. Check condition of
radiator hoses. If they swell excessively while testing
system, they may be weak and should be replaced.
66
Gauge Needle Drops Quickly
A steady drop or loss of pressure indicates serious
leakage is occurring within system, which must be
located and corrected before engine is returned to
service.
If a pressure loss is noted:
1. With pressure on system, apply a soap/water
solution and check all joint connections, hoses, and
cooling system components for external leakage.
Repair or replace as required.
2. Remove dipstick and check appearance of oil in
crankcase. Another method would be to remove an
oil drain plug and drain a small amount of oil for
inspection. A milky or an opaque color, similar to
chocolate milk, indicates presence of engine coolant
in oil. Check for a blown head gasket (step 3 below)
or a possible crack or internal leakage from water
jacket.
3. Remove spark plugs. Apply 14-15 lbs. of pressure
and listen/inspect for internal coolant leakage into
cylinder/combustion chambers. This can denote a
head gasket failure/leak. If required, further test by
performing a Cylinder Leakdown Test as described
in Troubleshooting.
KohlerEngines.com
66 690 14 Rev. A
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