Ford 2003 Mustang Workshop Manual page 1904

Pressure Test
1. Turn the engine OFF.
2. WARNING: Never remove the pressure relief cap under any conditions while the
engine is operating. Failure to follow these instructions could result in damage to the
cooling system or engine and/or personal injury. To avoid having scalding hot coolant or
steam blow out of the cooling system, never remove the pressure relief cap from a hot
degas bottle. Wait until the engine has cooled, then wrap a thick cloth around the
pressure relief cap and turn it slowly one turn (counterclockwise). Step back while the
pressure is released from the cooling system. When certain all the pressure has been
released, remove the pressure relief cap (still with a cloth).
Check the intercooler coolant level. For additional information, refer to
System Draining, Filling and Bleeding
3. Connect the Radiator/Heater Core Pressure Tester to the degas bottle nipple. Install a pressure
test pump to the quick-connect fitting of the test adapter.
4. NOTE: If the plunger of the pump is depressed too fast, an erroneous pressure reading will
result.
Slowly depress the plunger of the pressure test pump until the pressure gauge reading stops
increasing and note the highest pressure reading obtained.
5. If the pressure relief cap does not hold pressure, remove and wash the pressure relief cap in
clean water to dislodge all foreign particles from the gaskets. Check the sealing surface in the
filler neck.
6. If 69 kPa (10 psi) cannot be reached, install a new pressure relief cap. If more than 12 kPa (18
psi) shows on the gauge, install a new pressure relief cap.
7. CAUTION: If the pressure drops, check for leaks at the intercooler hoses or other
system components and connections. Any leaks which are found must be corrected and
the system rechecked.
NOTE: Intercooler system is not connected to the main engine cooling system.
Pressurize the intercooler cooling system as described in Step 4 (using a pressure relief cap
that operates within the specified upper and lower pressure limits). Observe the gauge reading
for approximately two minutes; refer to General Specifications. Pressure should not drop during
this time.
If the pressure drops and no external leak is found, the intercooler may be the cause.
Remove and inspect the intercooler. Install a new intercooler if necessary.
8. Release the system pressure by loosening the pressure relief cap. Check the coolant level and
replenish, if necessary, with the correct coolant mixture. For additional information, refer to
Supercharger Cooling System Draining, Filling and Bleeding
Cap
WARNING: Never remove the pressure relief cap under any conditions while the engine is
in this section.
Supercharger Cooling
in this section.