Ford 2003 Mustang Workshop Manual page 1848

PINPOINT TEST B: THE ENGINE OVERHEATS
B1 CHECK THE ENGINE COOLANT LEVEL
WARNING: Never remove the pressure relief cap while
the engine is operating or when the cooling system is hot.
Failure to follow these instructions can result in damage to
the cooling system or engine or personal injury. To avoid
having scalding hot coolant or steam blow out of the degas
bottle when removing the pressure relief cap, wait until the
engine is cooled, then wrap a thick cloth around the
pressure relief cap and turn it slowly. Step back while the
pressure is released from the cooling system. When you are
sure all the pressure has been released, turn and remove
the pressure relief cap (still with a cloth). NOTE: If the engine
is hot, allow the engine to cool before proceeding.
Key in OFF position.
Check the engine coolant level at the degas bottle/coolant
expansion tank.
Is the engine coolant OK?
B2 CHECK THE COOLANT CONDITION
Check the coolant for dirt, rust or contamination.
Is the coolant condition OK?
B3 CHECK FOR AN AIRFLOW OBSTRUCTION
Inspect the A/C condenser core and radiator for obstructions
such as leaves or dirt.
Is there an obstruction?
B4 CHECK THE WATER THERMOSTAT OPERATION
Start the engine and allow the engine to run for ten minutes.
Feel the inlet and outlet heater water hoses and the underside of
the upper radiator hose.
Are the upper radiator hose and the heater water hoses
cold?
Test Step
Result / Action to
Take
Yes
GO to B2 .
No
REFILL the engine
coolant at the degas
bottle/coolant
expansion tank. Go To
Pinpoint Test A .
Yes
GO to B3 .
No
FLUSH the engine
cooling system.
REFER to Engine and
Radiator Flushing in
this section. TEST the
system for normal
operation.
Yes
REMOVE the
obstruction. CLEAN the
A/C condenser core
and radiator. TEST the
system for normal
operation.
No
GO to B4 .
Yes
INSTALL a new water
thermostat. REFER to
Thermostat—3.8L ,
Thermostat—4.6L(2V)
or Thermostat—4.6L
(4V) in this section.
TEST the system for
normal operation.
No
GO to B5 .