CONDITION
POSSIBLE CAUSE
CORRECTION
10. Air leak on the suction side of
water pump allows air to build up in
cooling system. This will cause the
thermostat to open late.
10. Locate leak and repair as
necessary.
PRESSURE CAP IS BLOWING
OFF STEAM AND/OR COOLANT
FLOWING INTO RECOVERY
CONTAINER. TEMPERATURE
GAUGE READING MAY BE ABOVE
NORMAL, BUT NOT HIGH.
COOLANT LEVEL MAY BE HIGH
IN RECOVERY CONTAINER.
1. Pressure relief valve in radiator
cap is defective.
1. Check condition of radiator cap
and seals. Refer to Radiator Cap in
this section. Replace as necessary.
COOLANT LOSS TO THE
GROUND WITHOUT PRESSURE
CAP BLOWOFF. GAUGE IS
READING HIGH OR HOT.
1. Coolant leaks in radiator, cooling
system hoses, water pump or
engine.
1. Pressure test and repair as
necessary. Refer to Testing Cooling
System For Leaks in this section.
DETONATION OR PRE-IGNITION
(NOT CAUSED BY IGNITION
SYSTEM). GAUGE MAY OR MAY
NOT BE READING HIGH.
1. Engine overheating.
1. Check reason for overheating
and repair as necessary.
2. Freeze point of coolant not
correct.
2. Check the freeze point of the
coolant. Refer to Coolant
Concentration Testing in this
section. Adjust glycol-to-water ratio
as required.
HOSE OR HOSES COLLAPSE
WHEN ENGINE IS COOLING
1. Vacuum created in cooling
system on engine cool-down is not
being relieved through coolant
recovery/reserve container system.
1. (a) Radiator cap relief valve
stuck. Refer to Radiator Cap in this
section. Replace as necessary.
(b) Hose between coolant
recovery/reserve container and
radiator is kinked. Repair as
necessary.
(c) Vent at coolant recovery/reserve
container is plugged. Clean vent
and repair as necessary.
(d) Recovery/reserve container is
internally blocked or plugged. Check
for blockage and repair as
necessary.
ELECTRIC RADIATOR FAN
OPERATES ALL THE TIME.
1. Fan relay, powertrain control
module (PCM) or engine coolant
temperature sensor defective.
1. Refer to appropriate Powertrain
Diagnostic Procedures manual for
operation of the DRB scan tool.
Repair as necessary.
2. Check for low coolant level.
2. Repair as necessary.
JX
COOLING SYSTEM
7 - 11
DIAGNOSIS AND TESTING (Continued)