Section 03-03: Engine Cooling
1993 Mustang Workshop Manual
DIAGNOSIS AND TESTING

Fan Drive Clutch Test

 

5.0L Only

Tools Required:

Spin the fan blade. 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:

 

Minimum Speed Fan Drive Requirement Test—Cold

  1. Using a suitable marker, mark the water pump pulley hub, one of the fan blade retaining bolts and the crankshaft pulley.
  1. Connect a tachometer to the engine.
  1. Install a throttle adjusting tool.
  1. Connect a Sun Strobe Light or equivalent. This can be a SLT-1 or SLT-2 Strobotach or a STA-1 Strobe Trigger adapter for the Sun Distributor Test Stand. A Rotunda Digital Photoelectric Tachometer 055-00108 or equivalent may also be used for this test.

     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.

  1. Start the engine and run it at approximately 1000 rpm until engine temperature has normalized.
  1. Adjust the engine to the specified engine testing speed.
  1. Operate the strobe light at 2000 rpm and aim it at the water pump pulley. Adjust the engine speed until the light flashes and the water pump pulley mark are synchronized.
  1. Aim the timing light at the fan blade retaining bolts. Adjust the strobe light until it is synchronized with the marked fan retaining bolt (fan blade appears to stand still).
  1. The fan speed must not be greater than the specified fan test speed at 2000 water pump rpm.
  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 drive clutch.

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

  1. If the maximum speed fan drive requirement test is going to be performed, do not remove the tachometer, strobe light or throttle adjusting tool.
  1. If a maximum speed fan drive requirement test is not going to be performed, remove the tachometer, strobe light and throttle adjusting tool.
 

Maximum Speed Fan Drive Requirement Test

  1. If the minimum speed fan drive requirement test was not performed, follow Steps 1 through 5 under minimum speed fan drive requirement test.
  1. Block off areas on each side of the radiator core in the engine compartment and the front of the grille. This will raise the temperature of the air striking the clutch control unit and should cause the fan to operate at maximum speed.
  1. Place the air conditioning selector, if so equipped, to the maximum position and the blower switch to the high position.
  1. Adjust the strobe light to 2000 rpm.

     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.

  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 marked fan to clutch retaining bolt.
  1. The fan speed must meet or exceed the specified maximum fan test speed at 2000 water pump rpm.
  1. If the fan speed was less than the specified fan test speed, replace the fan drive clutch.