CONDITION POSSIBLE CAUSES CORRECTION
3. Is cooling fan operating
correctly?
3. Refer to Cooling System Fan in
the section for diagnosis. Repair as
necessary.
4. Has undercoating been applied
to any unnecessary component?
4. Clean undercoating as necessary.
5. Engine may be running rich,
causing the catalytic converter to
overheat
5. Refer to appropriate Powertrain
Diagnostic Procedures manual for
operation of the DRB scan tool.
Repair as necessary.
POOR DRIVEABILITY
(THERMOSTAT POSSIBLY STUCK
OPEN). GAUGE MAY BE READING
LOW.
1. For proper driveability, clean
vehicle emissions and prevention of
buildup of engine oil sludge, the
thermostat must be operating
properly. Has a diagnostic trouble
code been set?
1. Refer to appropriate Powertrain
Diagnostic Procedures manual for
operation of the DRB scan tool.
Replace thermostat if necessary.
STEAM IS COMING FROM FRONT
OF VEHICLE NEAR GRILL AREA
WHEN WEATHER IS WET,
ENGINE WARMED UP AND
RUNNING WITH VEHICLE
STATIONARY, OR JUST SHUT
OFF. TEMPERATURE GAUGE IS
NORMAL.
1. During wet weather, moisture
(snow, ice, rain, or condensation)
on the radiator will evaporate when
the thermostat opens. The
thermostat opening allows heated
coolant into the radiator. When the
moisture contacts the hot radiator,
steam may be emitted. this usually
occurs in cold weather with no fan
or air flow to blow it away.
1. Occasional steam emitting from
this area is normal. No repair is
necessary.
COOLANT COLOR 1. Coolant color is not necessarily
an indication of adequate corrosion
or temperature protection. Do not
rely on coolant color for determining
condition of coolant.
1. Check the freeze point of the
coolant. Refer to Coolant in this
section for test procedure. Adjust
the ethylene glycol-to-water ratio as
necessary and service according to
maintenance schedule. Refer to
LUBRICATION AND
MAINTENANCE.
COOLANT LEVEL CHANGES IN
COOLANT BOTTLE.
TEMPERATURE GAUGE IS IN
NORMAL RANGE.
1. Level changes are to be
expected as coolant volume
fluctuates with engine temperature.
The coolant level will also drop as
the system removes air from a
recent filling.
1. A normal condition. No repair is
necessary.
ENGINE THERMOSTAT
The thermostat is operated by a wax filled con-
tainer (pellet) which is sealed so that when heated to
a predetermined temperature, the wax expands
enough to overcome the closing spring and water
pump pressure, which forces the valve to open. Cool-
ant leakage into the pellet will cause a thermostat to
fail open. Do not attempt to free up a thermostat
with a screwdriver.
The open too soon type failure mode is included in the
on-board diagnosis. The check engine light will not be
lit by an open too soon condition. If it has failed open, a
DTC diagnostic trouble code will be set. Do not change a
thermostat for lack of heat by gauge or heater perfor-
mance, unless a code is present, see diagnosis for other
probable causes. Failing shut is the normal long term
mode of failure, and normally, only on high mileage
vehicles. The temperature gauge will indicate this,
Refer to diagnosis in this section.
7 - 14 COOLING SYSTEM LH
DIAGNOSIS AND TESTING (Continued)
To Next Page
Loading...
