Ford Mustang/Cougar 1964-1973 Repair Guide

Fluid Pan



C-4, C-6, FMX Cruisomatic

Normal maintenance and lubrication requirements do not include periodic changes of transmission fluid. Only when it is necessary to remove the pan for major repairs or adjustments will it be necessary to replace the transmission fluid. At this time the converter, oil cooler core, and cooler lines should be thoroughly flushed out to remove any dirt or deposits that might clog these units later.

When filling a completely dry transmission and converter, install five quarts of transmission fluid, then start the engine. Shift the selector lever through all positions briefly and set at Park position. Check the fluid level and add enough fluid to raise the level to between the ADD and FULL marks on the dipstick. [cf2]Do not overfill the transmission.

The procedure for a partial drain and refill of the transmission fluid is as follows:

  1. Raise the car on a hoist or jack stands.
  3. Place a drain pan under the transmission pan.

On some models of the C-4 transmission, the fluid is drained by disconnecting the filler tube from the transmission fluid pan.

  1. Loosen the pan attaching bolts to allow the fluid to drain.
  3. When the fluid has stopped draining to level of the pan flange, remove the pan bolts starting at the rear and along both sides of the pan, allowing the pan to drop and drain gradually.
  5. Remove the eight screws that attach the oil screen to the body and remove the screen and gasket. Be careful not to lose the throttle pressure limit valve and spring when separating the oil screen from the valve body.
  7. After completing the transmission repairs or adjustments, install the fluid filter screen, a new pan gasket, and the pan on the transmission. Tighten the pan attaching bolts on C-4 and C-6 to (12-16 ft. lbs.). On FMX transmissions, tighten the pan attaching bolts to 10-13 ft. lbs.

Be sure to use Type F transmission fluid. The use of any other type of fluid such as Type A suffix A, or DEXRON will materially affect the service life of the transmission.

  1. Install three quarts of transmission fluid through the filler tube. If the filler tube was removed to drain the transmission, install the filler tube using a new O-ring.
  3. Start and run the engine for a few minutes at a low idle speed and then at the fast idle speed (about 1200 rpm) until the normal operating temperature is reached. [cf2]Do not race the engine.
  5. Move the selector lever through all positions and place it at the Park position. Check the fluid level and add fluid until the level is between the ADD and FULL marks on the dipstick. [cf2]Do not overfill the transmission.