Diagnosis And Testing Diagnosis And Testing - Cooling System Aeration; Diagnosis And Testing - Cooling System Deaeration; Diagnosis And Testing - Cooling System Flow Check; Diagnosis And Testing - Cooling System Leak Testing - Chrysler PT Cruiser Service & Repair Manual

7 - 14 ENGINE - 1.6L SOHC
ENGINE - 1.6L SOHC (Continued)
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - COOLING SYSTEM
AERATION
If coolant level drops below a certain point, aera-
tion will occur drawing air into the water pump
resulting in the following:
• High reading shown on the temperature gauge.
• Loss of coolant flow through the heater core.
• Corrosion in the cooling system.
• Transmission oil will become hotter (automatic
transmission equipped vehicles).
• Water pump seal may run dry, increasing the
risk of premature seal failure.
• Combustion gas leaks into the coolant can also
cause the above problems.
DIAGNOSIS AND TESTING - COOLING SYSTEM
DEAERATION
As air is removed from the cooling system, it gath-
ers in the coolant recovery container. This pressure is
released into the atmosphere through the pressure
valve located in the radiator pressure cap when pres-
sure reaches 96 - 124 kPa (14 - 18 psi). This air is
replaced with coolant from the coolant recovery con-
tainer.
NOTE: Deaeration does not occur at engine idle—
higher engine speeds are required. Normal driving
will deaerate cooling system.
To effectively deaerate the system, multiple ther-
mal cycles of the system may be required.
DIAGNOSIS AND TESTING - COOLING SYSTEM
FLOW CHECK
WARNING: DO NOT REMOVE THE COOLING SYS-
TEM PRESSURE CAP WITH THE SYSTEM HOT AND
UNDER PRESSURE BECAUSE SERIOUS BURNS
FROM COOLANT CAN OCCUR.
To determine whether coolant is flowing through
the cooling system, use one of the following proce-
dures:
• If engine is cold, idle engine until normal oper-
ating temperature is reached. Then feel the upper
radiator hose. If it is hot, coolant is circulating.
• Remove pressure cap when engine is cold,
remove small amount of coolant. Idle engine until
thermostat opens, you should observe coolant flow
while looking down the filler neck. Once flow is
detected install the pressure cap.
DIAGNOSIS AND TESTING - COOLING SYSTEM
LEAK TESTING
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT 15 MINUTES BEFORE REMOVING PRESSURE
CAP. PLACE A SHOP TOWEL OVER THE CAP, AND
WITHOUT PUSHING DOWN, ROTATE IT COUNTER-
CLOCKWISE TO THE FIRST STOP. ALLOW FLUIDS
TO ESCAPE THROUGH THE OVERFLOW TUBE.
WHEN THE SYSTEM STOPS PUSHING COOLANT
AND STEAM INTO THE COOLANT RECOVERY CON-
TAINER AND PRESSURE DROPS, PUSH DOWN ON
THE CAP AND REMOVE IT COMPLETELY. SQUEEZ-
ING THE RADIATOR INLET HOSE WITH A SHOP
TOWEL (TO CHECK PRESSURE) BEFORE AND
AFTER TURNING TO THE FIRST STOP IS RECOM-
MENDED.
With engine not running, wipe the coolant filler
neck sealing seat clean. The radiator should be full.
Attach a cooling system pressure tester (Tool 7700
or equivalent) to the coolant filler neck, as shown in
(Fig. 2) and apply 104 kPa (15 psi) pressure. If the
pressure drops more than 2 psi in 2 minutes inspect
all points for external leaks.
All hoses, radiator and heater, should be moved
while at 104 kPa (15 psi) since some leaks occur
while driving due to engine movement, etc.
Fig. 2 Pressure Testing Cooling System
1 - PRESSURE TESTER
PT