Chrysler 300M 2002 Service Manual page 182

LH
COOLING (Continued)
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - COOLING SYSTEM
CONDITION
TEMPERATURE GAUGE READING
IS INCONSISTENT (FLUCTUATES,
CYCLES OR IS ERRATIC).
PRESSURE CAP IS BLOWING OFF
STEAM AND/OR COOLANT.
TEMPERATURE GAUGE READING
MAY BE ABOVE NORMAL BUT NOT
HIGH. COOLANT LEVEL MAY BE
HIGH IN COOLANT RESERVE/
OVERFLOW TANK.
POSSIBLE CAUSES
1. During cold weather operation with
the heater blower in the high position,
the gauge reading may drop slightly.
Fluctuation is also influenced by
loads, outside temperature, and
cycling of the air conditioning system.
2. Temperature gauge or engine
sending unit sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.
3. Gauge reading rises when vehicle
is brought to a stop after heavy use
(engine still running).
4. Gauge reading high after restarting
a warmed-up (hot) engine.
5. Coolant level low (air will build up
in the cooling system causing the
thermostat to open late).
6. Cylinder head gasket leaking
allowing exhaust gas to enter cooling
system causing thermostat to open
late.
7. Water pump impeller loose on
shaft.
8. Air leak on the suction side of
water pump allows air to build up in
cooling system causing thermostat to
open late.
1. Pressure relief valve in radiator
cap is defective, or was not properly
seated.
2. Incorrect cap was installed.
3. Incorrect coolant mixture.
4. System overfilled.
COOLING 7 - 3
CORRECTION
1. A normal condition. No correction is
necessary.
2. Check operation of gauge and
repair if necessary. Refer to
INSTRUMENT PANEL AND
SYSTEMS.
3. A normal condition. No correction is
necessary. Gauge reading should
return to normal range after vehicle is
driven.
4. A normal condition. No correction is
necessary. The gauge should return
to normal range after a few minutes of
engine operation.
5. Check and correct coolant leaks.
Refer to Testing Cooling System for
Leaks in this section.
6. (a) Check for cylinder head gasket
leaks with a commercially available
block leak tester. Repair as
necessary.
(b) Check for coolant in engine oil.
Inspect for white steam emitting from
exhaust system. Repair as necessary.
7. Check water pump and replace as
necessary. Refer to Water Pump
Removal in this section.
8. Locate leak and repair as
necessary.
1. Check condition of radiator cap and
cap seal. Refer to Pressure Cap in
this group. Replace cap as necessary.
2. Replace cap as necessary.
3. Make sure a 50% by volume
mixture of coolant is used.
4. Ensure cold coolant level is
between MIN and MAX marks on
coolant bottle.