Chrysler PT Cruiser. Manual - part 460
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 BOT-
TLE AND PRESSURE DROPS, PUSH DOWN ON THE
CAP AND REMOVE IT COMPLETELY. SQUEEZING
THE RADIATOR INLET HOSE WITH A SHOP TOWEL
(TO CHECK PRESSURE) BEFORE AND AFTER
TURNING TO THE FIRST STOP IS RECOMMENDED.
The cooling system should be full. Add coolant if
necessary.
With engine not running, wipe the coolant filler
neck sealing seat clean.
Attach a cooling system pressure tester (Special
Tool 7700 or equivilent) to the coolant filler neck, as
shown in (Fig. 4) and apply 104 kPa (15 psi) pres-
sure. If the pressure drops more than 2 psi in 2 min-
utes inspect all points for external leaks. For Special
Tool identification, (Refer to 7 - COOLING - SPE-
CIAL TOOLS).
Move all hoses at the radiator and heater while
system is pressurized at 104 kPa (15 psi), since some
leaks occur while driving due to engine movement
while driving.
If there are no external leaks after the gauge dial
shows a drop in pressure, detach the tester. Start
engine and run the engine to normal operating tem-
perature in order to open the thermostat and allow
the coolant to expand. Reattach the tester. If the nee-
dle on the dial fluctuates, it indicates a combustion
leak and is usually a head gasket leak.
WARNING:
WITH
TOOL
IN
PLACE
PRESSURE
BUILDS UP FAST. ANY EXCESSIVE AMOUNT OF
PRESSURE BUILT UP BY CONTINUOUS ENGINE
OPERATION MUST BE RELEASED TO A SAFE
PRESSURE POINT. NEVER PERMIT PRESSURE TO
EXCEED 138 kPa (20 psi).
If the needle on the dial does not fluctuate, race
the engine a few times. If an abnormal amount of
coolant or steam is emitted from the tailpipe, it may
indicate a faulty head gasket, cracked engine block or
cylinder head.
There may be internal leaks which can be deter-
mined by removing the oil dipstick. If water globules
appear intermixed with the oil, it will indicate a
internal leak in the engine. If there is an internal
leak, the engine must be disassembled for repair.
DIAGNOSIS AND TESTING - COOLING SYSTEM
FLOW CHECK
To determine whether coolant is flowing through
the cooling system, use one of the following proce-
dures:
PREFERRED METHOD
WARNING: DO NOT REMOVE THE COOLING SYS-
TEM PRESSURE CAP OR ANY HOSE WITH THE
SYSTEM HOT AND UNDER PRESSURE BECAUSE
SERIOUS BURNS FROM COOLANT CAN OCCUR.
• 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. Replace removed
coolant into coolant recovery container.
ALTERNATIVE METHOD
• If engine is cold, idle engine until normal oper-
ating temperature is reached. Feel the upper radiator
hose. If it is hot, coolant is circulating.
COOLING SYSTEM AERATION
Low coolant level in the cooling system will cause
aeration, resulting in the following conditions:
• Corrosion in the system
• High reading shown on the temperature gauge
• Loss of coolant flow through the heater
• Exhaust gas leaks into the coolant can also
cause the above problems
Fig. 4 Pressure Testing Cooling System
1 - SPECIAL TOOL 7700
7 - 42
ENGINE - 2.0/2.4L DOHC
PT
ENGINE - 2.0/2.4L DOHC (Continued)