Fulltext TSBs

Technical Service Bulletins

TSB
99-1-6
  • CLUTCH – LOW CLUTCH PEDAL ENGAGEMENT – VEHICLES BUILT THROUGH 9/12/1998 WITH 7.3L ENGINE AND M6 TRANSMISSION
Publication Date: JANUARY 12, 1999

LIGHT TRUCK:
1999 SUPER DUTY F SERIES

This TSB article is being republished in its entirety to revise the Service Procedure, and add Service Part Numbers.

ISSUE:

A low clutch pedal engagement and/or hard shifting after operating several kilometers/miles may occur on some vehicles. This may be caused by air in the clutch hydraulic system, loss of clutch hydraulic fluid, or ballooning of the clutch hydraulic line damper due to temperature and added clutch load causing the clutch to release with pedal against the down stop or not release at all.

ACTION:

Check for air in the hydraulic line of the clutch slave cylinder and/or proper fluid amount in cylinder. If fluid is sufficient and no air is in the system, refer to the following Service Procedure for details.

SERVICE PROCEDURE

Check to make sure the routing of the reservoir-to-master cylinder line is not looped over the brake master cylinder reservoir thereby allowing air to be trapped in the line. The line should be routed from the master cylinder across the lower front of the brake master cylinder reservoir to the clutch reservoir. Then verify if the clutch hydraulic system has fluid in the reservoir.

If the reservoir is low or no fluid is observed, determine if a leak is present and proceed to install new component as required; master cylinder, hydraulic line between master cylinder and slave cylinder, slave cylinder or reservoir to master cylinder.

If the reservoir shows sufficient fluid, then proceed to fix issue by changing the Clutch Hydraulic Line to one without a damper (F81Z-7A512-BA) along with changing the Clutch Pedal Assembly to one with more travel (F81Z-7B633-BC). Proceed as follows:

Refer to the 1999 Super Duty F-Series Workshop Manual, Pages 308-02-3 through 308-02-10, for reference to the following.

  1. Remove the master cylinder pushrod from the clutch pedal assembly pin.
  2. Remove the safety start switch from the pushrod by first removing the switch dust cover.
  3. Remove the master cylinder and pushrod assembly from the pedal assembly by compressing and twisting the master cylinder clockwise in the pedal assembly.
  4. Remove the clutch hydraulic system by removing the reservoir push pins attaching reservoir to the wiring tray.
  5. Twist and unlock the slave cylinder from the transmission.
  6. Remove the line from the floor and dash clips and remove the clutch hydraulic system from the vehicle.
  7. Remove the hydraulic line with the hose damper from the slave cylinder by using a 3/32″ punch to drive out the line holding pin and pull the line from slave cylinder.
  8. Proceed to remove the other end of the line from the master cylinder similar to the slave cylinder by removing the roll pin and pulling the line off.
  9. Remove the pedal assembly from the dash by removing four (4) attaching nuts.
  10. Check to be sure the O-ring was removed from both the slave cylinder and master cylinder before assembling the new line. If they were not, remove the old O-ring.
  11. Obtain the new Clutch Hydraulic Line (F81Z-7A512-BA). Make sure O-rings/seals are on each end of the line before assembling.
  12. Apply DOT-3 Brake Fluid (C6AZ-19542-AB) to the new line O-rings/seals and proceed to install new line to the master cylinder and secure with roll pin.
  13. Hang the system from the reservoir. Straighten out the hydraulic system with the reservoir above the master cylinder and the master cylinder above the slave cylinder end. Place the slave cylinder end of the line end into a container for waste fluid.
  14. Fill the system by adding DOT-3 brake fluid to the reservoir until the fluid runs out the line where the slave cylinder is to be attached, allowing fluid to purge air from the system (which takes 2 to 3 fills of the reservoir). Then cap the line.
  15. Prepare the slave cylinder by holding the cylinder so that the port for the line is at the highest point, then fill the extended slave cylinder with fluid.
  16. Remove the line cap and install the filled slave cylinder on the line and secure with roll pin.
  17. Proceed to stroke the slave cylinder slowly by pushing on the end of the slave cylinder pushrod until there are no air bubbles present at the clutch hydraulic reservoir (5 to 10 times). Push the pushrod until it bottoms out in the slave cylinder each time.
  18. Check the reservoir to make sure system is still full of fluid.
  19. Proceed to install the new Clutch Pedal Assembly (F81Z-7B633-BC).
  20. Install the hydraulic system.
  21. Twist and lock master cylinder to pedal assembly with a 45 degree counterclockwise turn.
  22. Route the hydraulic line from the master cylinder to the reservoir across the front of the lower brake master cylinder taking special notice to not put loop in the routing high points.
  23. Reinstall hydraulic reservoir to wiring tray with push pins.
  24. Install new Bushing (E69Z-7526-A) to master cylinder pushrod.
  25. Reinstall the master cylinder pushrod to the pedal assembly pin.
  26. Install the switch-to-master cylinder pushrod by snapping onto the rod and reinstalling the dust cover.
  27. Align the switch to the tab protruding from the master cylinder which positions the wiring connection at 1 o’clock on pre-February 1998 production vehicles and at 12 o’clock on those vehicles produced after January 1998.

    CAUTION:ALIGN THE SWITCH TO THE TAB ON THE FACE OF THE MASTER CYLINDER WHEN THE SWITCH IS REINSTALLED – RISK OF DAMAGING SWITCH AND INSUFFICIENT PEDAL TRAVEL.

  28. Twist and lock the slave cylinder into the transmission.
  29. Realign the hydraulic line to the clips on the floor pan and dash.
  30. Proceed to slowly depress and release the clutch pedal 5 to 10 times to allow any additional air to bleed from the hydraulic system.
  31. Recheck to assure the hydraulic reservoir is full.

Verify that the low clutch pedal engagement has been fixed by checking the clutch engagement point on the repaired vehicle (assuming vehicle is unloaded and on level ground):

  1. Start the engine with the transmission in Neutral.
  2. Move the shift control to 1st gear location.
  3. Slowly release the clutch pedal from the down stop until vehicle creeps/starts to roll.
  4. Measure this point down to the stop; this travel should be at least 44mm (1.75″).

If the amount of pedal travel to engagement is less than 44mm (1.75″), proceed to bleed additional air from the hydraulic system:

  1. Remove the slave cylinder from the transmission case.

    CAUTION:DO NOT STROKE (DEPRESS) THE CLUTCH PEDAL WITH SLAVE CYLINDER REMOVED FROM CLUTCH HOUSING – RISK OF PUSHING PISTON OUT OF CYLINDER.

  2. Unclip hydraulic line from the floor pan.
  3. Straighten out the hydraulic system so that the slave cylinder rod opening is facing down and the hydraulic line is routed up toward the master cylinder so that there are no “high points” in the system to prevent air bubbles from rising through the system to the fluid reservoir.
  4. Verify the fluid reservoir is full during this bleed procedure to prevent air from entering the hydraulic system. Be sure there are no high points to trap bubbles.
  5. Push the slave cylinder pushrod fully into the slave cylinder, bottoming the piston, to force air out of the slave cylinder and into the hydraulic line. Hold fully bottomed for 5-10 seconds to allow all bubbles to rise through the system.
  6. Very slowly, so air is not drawn back into the slave cylinder, release the pushrod (the spring in the slave cylinder will force the piston outward).
  7. Wait 5-10 seconds for the bubbles to rise.
  8. Repeat Steps 5 through 7 until all air is expelled from the system (watch for air bubbles at the fluid reservoir).
  9. Twist and lock the slave cylinder back into the transmission.
  10. Once the slave cylinder is back in place, slowly depress and release the clutch pedal 5 to 10 times to bleed any air bubbles still trapped to the clutch fluid reservoir.

    NOTE:IF YOU EXPERIENCE A REPEAT LOW CLUTCH CONCERN ON 1999 F-SUPER DUTY WITH 7.3L/M60D AND ARE HAVING PROBLEMS WITH BLEEDING AIR FROM THE CLUTCH HYDRAULIC SYSTEM, INSPECT FOR PREVIOUS REPAIR ON THE FOLLOWING: 1) CLUTCH LINE BETWEEN THE MASTER CYLINDER AND SLAVE CYLINDER FOR A HOSE DAMPER, AND 2) A NEW CLUTCH PEDAL (F81A-7B633-BC EMBOSSED ON LH SIDE OF PEDAL SUPPORT BRACKET).

    IF THE LINE DOES HAVE A HOSE DAMPER, REPLACE IT WITH A NEW CLUTCH HYDRAULIC LINE (F81Z-7A512-BA) PER THE PROCEDURE DESCRIBED WITHIN THIS TSB. IF THE NEW PEDAL HAS NOT BEEN INSTALLED, OBTAIN A NEW CLUTCH PEDAL ASSEMBLY (F81Z-7B633-BC) AND PUT THE NEW PEDAL INTO THE VEHICLE.

    IF THE NEW LINE AND PEDAL HAVE BEEN INSTALLED AND YOU ARE STILL EXPERIENCING REPEAT LOW CLUTCH CONCERN, YOU MAY TRY A PRE-BLED ALREADY FILLED CLUTCH HYDRAULIC ACTUATION CONTROL ASSEMBLY (MASTER CYLINDER, LINE, SLAVE CYLINDER, AND RESERVOIR) (F81Z-7C522-AJ). YOU WILL ALSO NEED TO OBTAIN A NEW MASTER CYLINDER PUSHROD (F81Z-2143-BA) FOR THE SYSTEM INSTALLATION. REUSE THE SWITCH ASSEMBLY.

    IF THIS DOES NOT RESOLVE THE ISSUE, INSPECT THE CLUTCH AND REPLACE IF REQUIRED (CLUTCH DISC IS F81Z-7550-HB AND THE COVER/PRESSURE PLATE IS F81Z-7563-DA).


PART NUMBERPART NAME
F81Z-7A512-BAClutch Hydraulic Line
F81Z-7B633-BCClutch Pedal Assembly
E69Z-7526-AMaster Cylinder Pushrod Bushing
F81Z-7C522-AJMaster Cylinder Assembly
F81Z-2143-BAMaster Cylinder Pushrod
F81Z-7550-HBClutch Disc
F81Z-7563-DACover/Pressure Plate
C6AZ-19542-ABDOT-3 Brake Fluid

OTHER APPLICABLE ARTICLES:

NONE

SUPERSEDES:

98-24-7

WARRANTY STATUS:

Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage

OPERATIONDESCRIPTIONTIME
990106AReplace Clutch Hydraulic Line And Clutch Pedal Assembly1.3 Hrs.
990106BAdditional Time To Bleed System0.2 Hr.

DEALER CODING

BASIC PART NO.CONDITION CODE
7A51253

OASIS CODES:

506000


Copyright 1999 Ford Motor Company