Chrysler 2000 LHS Owner's Manual page 203

7 - 14 COOLING SYSTEM
DIAGNOSIS AND TESTING (Continued)
CONDITION
POOR DRIVEABILITY
(THERMOSTAT POSSIBLY STUCK
OPEN). GAUGE MAY BE READING
LOW.
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.
COOLANT COLOR
COOLANT LEVEL CHANGES IN
COOLANT BOTTLE.
TEMPERATURE GAUGE IS IN
NORMAL RANGE.
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.
POSSIBLE CAUSES
3. Is cooling fan operating
correctly?
4. Has undercoating been applied
to any unnecessary component?
5. Engine may be running rich,
causing the catalytic converter to
overheat
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. 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. 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. 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.
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.
CORRECTION
3. Refer to Cooling System Fan in
the section for diagnosis. Repair as
necessary.
4. Clean undercoating as necessary.
5. Refer to appropriate Powertrain
Diagnostic Procedures manual for
operation of the DRB scan tool.
Repair as necessary.
1. Refer to appropriate Powertrain
Diagnostic Procedures manual for
operation of the DRB scan tool.
Replace thermostat if necessary.
1. Occasional steam emitting from
this area is normal. No repair is
necessary.
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.
1. A normal condition. No repair is
necessary.
LH