Section 03-03: Engine Cooling
1996 F-150, F-250, F-350, F-Super Duty, Bronco Vehicles and F-250, F-350 and F-Super Duty Vehicles with 7.3L Diesel Engines Workshop Manual
DIAGNOSIS AND TESTING

Component Tests

 

Pressure Test

 
  1.  WARNING: NEVER REMOVE THE RADIATOR CAP (8100) OR DEGAS BOTTLE CAP UNDER ANY CONDITIONS WHILE THE ENGINE (6007) IS OPERATING. FAILURE TO FOLLOW THESE INSTRUCTIONS COULD RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE OR PERSONAL INJURY. TO AVOID HAVING SCALDING HOT COOLANT OR STEAM BLOW OUT OF THE RADIATOR (8005), USE EXTREME CARE WHEN REMOVING THE RADIATOR CAP OR DEGAS BOTTLE CAP FROM A HOT RADIATOR. WAIT UNTIL THE ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE RADIATOR CAP OR DEGAS BOTTLE CAP AND TURN IT SLOWLY TO THE FIRST STOP. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN YOU ARE SURE ALL THE PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE RADIATOR CAP OR DEGAS BOTTLE CAP (STILL WITH A CLOTH), TURN AND REMOVE IT.

    Shut the engine off.

  1. Open hood and install protective fender covers.

  1. When engine is cool, cautiously remove radiator cap or degas bottle cap.

  1. Disconnect battery.

  1. Adjust the radiator coolant level (fill or drain) to 25mm (one inch) below the filler neck opening before testing. Wipe clean, and then wet the rubber sealing surfaces in the cap and filler neck before installing the radiator cap tightly on the radiator.

  1. Disconnect the electrical connector from the coolant temperature sending unit and remove the temperature sending unit from the engine.

    With the radiator cap installed and the cooling system pressure relieved, only a small amount of coolant will be lost when the sending unit is removed.

  1. Install the adapter fitting from Rotunda Radiator/Heater Core Pressure Tester 021-00013 or equivalent (male thread on one end, and a hose connector on the other end to accommodate the tester hose) tightly into the intake manifold (9424) or cylinder head (6049) in place of the sending unit.

  1. On Bronco, F-150, F-250, F-350 and F-Super Duty series vehicles, remove the radiator overflow hose (8075) from the overflow nipple. Install a separate radiator overflow hose firmly on the overflow nipple. Insert the free end of separate radiator overflow hose into container of water.

  1. Attach the pressure pump and gauge to the adapter-fitting and pressurize the cooling system to 69 kPa (10 psi).

    No bubbles should appear in the water container when the system is pressurized to the LOWER LIMIT (69 kPa [10 psi]). If the system is satisfactory at the lower limit, gradually increase the system pressure until a slight stream of bubbles appears in the water container. This is the release pressure of the pressure cap.

    Replace any radiator cap or degas bottle cap that has a release pressure that is greater than the specified UPPER LIMIT pressure (90 kPa [13 psi]) without discharging bubbles.

  1. If the radiator cap or degas bottle cap does not hold pressure, remove and wash the radiator cap or degas bottle cap in clean water to dislodge all foreign particles from the gaskets. Check the sealing surface in the radiator filler neck.

    Inspect the cam lock flanges on both sides of the filler neck for maximum cap engagement.

  1. Pressurize the cooling system as described in Step 6 (using a radiator cap and degas bottle cap that operate within the specified upper and lower pressure limits) and observe the gauge reading for approximately two minutes. Pressure should be held between 69 and 90 kPa (10 and 13 psi) and should not drop during this time.

  1. If the pressure drops, check for leaks at the engine-to-heater core hoses, engine-to-radiator hoses, bypass hose, water valve hose (if applicable), thermostat housing gasket, radiator and heater core (18476). Also refer to engine system checks if a leak cannot be located in the cooling system. Any leaks that are found must be corrected and the system checked again.

    If the system holds pressure, proceed to next step.

  1. Release the system pressure by loosening the radiator cap and removing the adapter. Install the water temperature indicator sender unit (10884), check coolant level and replenish, if necessary, with the correct coolant solution.

  1. NOTE: When the battery has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module (PCM) (12A650) relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 miles) or more to relearn the strategy.

    Connect battery ground cable.

 

Radiator Cap Pressure Test

 
  1. Remove the radiator cap from the radiator filler neck.

  1. Use water to clean the radiator cap in the area of the rubber seal and the vacuum relief valve as described in Radiator Cap in the Cleaning and Inspection portion of this section. Immerse the radiator cap in water to wet the seals and install on the shallow filler neck of Rotunda Radiator/Heater Core Pressure Tester Adapter 021-00013 or equivalent. (The adapter is designed to accept both deep and shallow neck radiator caps.)

  1. Before installing the radiator cap on the adapter, immerse the filler neck seal in water and install it in the filler neck adapter. If the adapter is made of plastic, check its sealing surfaces to be certain that they are free of rough spots and contain no parting lines or core marks.

    The filler neck seal is reversible so that it may be used on either a deep or shallow radiator filler neck. It will also fit either end of the radiator cap pressure test adapter.

  1. Install the filler neck adapter with filler neck seal on the deep filler neck end to the radiator cap pressure test adapter.

  1. Connect the female quick disconnect fitting of the pressure test pump to the male quick disconnect fitting of the filler neck adapter.






    ItemPart NumberDescription
    18100Radiator Cap
    2Filler Neck Seal
    (Part of 107-01301)
    3Filler Neck Adapter
    (Part of 107-01301)
    4Quick Disconnect Fittings
    (Part of 107-01301)
    5Temperature Sender Pressure Hose Adapter
    (Part of 107-01301)
    6Pressure Test Pump 021-00013 or Equivalent (Part of 107-01301)
    7Pressure Relief Screw
    (Part of 107-01301)
    8Radiator Cap Pressure Test Adapter (Part of 107-01301)
  1. SLOWLY depress the pump plunger of the pressure test pump until the pressure gauge reading stops increasing and note the highest pressure reading obtained. If the plunger of the pump is depressed too fast, an erroneous pressure reading will result.

  1. Release the pressure by depressing the pressure relief valve stem. Then, tighten the pressure relief screw and repeat Step 6 (at least twice) to make sure the pressure test reading is repeatable within the acceptable gauge reading limits of the radiator cap and is not erratic. Refer to Specifications at end of this section.

  1. If the pressure test gauge readings are not within the acceptable gauge reading limits, replace the radiator cap, and perform the pressure test. If the pressure test gauge readings are within the acceptable gauge reading limits, perform the pressure test.

 

Thermostat, Water

 

Perform the following inspection at approximately 22°C (72°F).

If the problem being investigated is insufficient heat, inspect the water thermostat (8575) for leakage. Hold the water thermostat up to a lighted background. Light leakage around the water thermostat valve (water thermostat at room temperature) is unacceptable and the water thermostat should be replaced. A slight leakage of light at one or two locations on the perimeter of the valve of some water thermostats may be detected. This is considered normal.

 

Radiator Leak Test, Removed from Vehicle

 CAUTION: Do not leak test an aluminum radiator in the same water that is used to leak test copper/brass radiators. Flux and caustic cleaners may be present in the tank and they will attack aluminum.

Clean the radiator before leak testing to prevent contaminating the test tank. Leak test the radiator in clean water at 145 kPa (21 psi) air pressure.

A separate, clean test tank is recommended for aluminum radiators. If a separate tank is not available for aluminum radiator testing, thoroughly clean the test tank each time before testing an aluminum radiator.

 

Fan Clutch Test

 

Spin the fan. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:

Refer to Fan Clutch Specifications at the end of this section.

Minimum Fan Clutch Requirement Test Cold

  1.  WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

    Using a suitable marker, mark the water pump pulley (8509), one of the fan blade retaining bolts and the crankshaft pulley (6312).

  1. Connect a tachometer to the engine.

  1. Install a throttle adjusting tool.

  1. Connect a Sun Strobe Light or equivalent. This can be an SLT-1 or SLT-2 Strobotach or an STA-1 Strobe Trigger adapter for the Sun Distributor Test Stand. A Digital Photoelectric Tachometer 055-00108 or equivalent may also be used for this test.

  1. Start the engine and run it at approximately 1500 rpm until engine temperature has normalized.

  1. Adjust the engine to the testing speed in the Specificationsat the end of this section.

  1. Operate the strobe light at water pump test speed and aim it at the water pump pulley. Adjust the engine speed until the light flashes and the water pump pulley marks are synchronized.

  1. Aim the timing light at the fan retaining bolts. Adjust the strobe light until it is synchronized with the marked fan retaining bolt (fan appears to stand still).

  1. The fan speed must not be greater than the specified fan test speed at water pump test speed.

  1. Turn the engine OFF.

  1. If the fan speed was greater than the specified fan test speed, check for proper parts usage.

    If the correct parts are used, replace the fan clutch (8A616).

    If the part(s) are not the correct ones, replace the part(s) and perform the test again.

  1. If the engaged fan clutch requirement test is going to be performed, do not remove the tachometer, strobe light or throttle adjusting tool.

  1. If a Maximum Speed Fan Clutch Requirement test is not going to be performed, remove the tachometer, strobe light and throttle adjusting tool.

Maximum Speed Fan Clutch Requirement Test

  1.  WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE WITH THE HOOD OPEN UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

    If the disengaged fan clutch requirement test was not performed, follow Steps 1 through 5 under Minimum Speed Fan Clutch Requirement test.

  1. Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille (8200), this will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.

  1. Place the air conditioning selector, if so equipped, in the maximum position and the blower switch in the high position.

  1. Adjust the strobe light to water pump test speed.

  1. Start the engine and adjust it until the water pump pulley is synchronized with the strobe light. This will be near the engine testing speed given in Specifications.

  1. Synchronize the timing light with the fan to fan clutch retaining bolt.

  1. The fan speed must meet or exceed the specified minimum fan blade test speed at water pump test speed.

  1. If the fan speed was less than the specified fan test speed, replace the fan clutch.