Clutch Master Cylinder

This procedure covers removal and replacement of the clutch master cylinder on a 2007 Ram 3500 with 5.9L Cummins diesel and manual transmission, including brake fluid bleeding.

Warnings

Tools required

Parts

• Clutch master cylinder × 1 — Use OEM specification
• Master cylinder pushrod clip (if damaged) × 1 — Use OEM specification

Fluids

• DOT 3 brake fluid — 0.5 qt

Preparation

1. Park vehicle on level ground and set parking brake
2. Chock rear wheels securely
3. Open hood and locate brake fluid reservoir on driver side firewall
4. Use turkey baster or extraction pump to remove brake fluid from reservoir to prevent overflow during master cylinder removal
5. Place drain pan and rags under master cylinder work area to catch spilled fluid
6. Apply penetrating oil to hydraulic line fittings at master cylinder and allow to soak for 10-15 minutes

Procedure

1. 1

   Access clutch master cylinder
   From inside the cab, locate the clutch pedal assembly. The master cylinder is mounted to the firewall on the driver side, accessed from under the dashboard. Remove the lower dash panel if equipped to improve access to the pedal assembly and master cylinder pushrod connection.
2. 2

   Disconnect pushrod from clutch pedal
   Locate the pushrod connecting the master cylinder to the clutch pedal arm. Remove the retaining clip securing the pushrod pin to the pedal arm using pliers. Slide the pushrod pin out to disconnect the pushrod from the pedal. Note the orientation of all components for reassembly.
3. 3

   Disconnect hydraulic line from master cylinder
   From the engine compartment, locate the hydraulic line connection at the master cylinder outlet. Using a flare nut wrench, carefully loosen and remove the hydraulic line fitting. Have rags ready to catch fluid. Cap or plug the line end immediately to prevent contamination and further fluid loss.
4. 4

   Remove master cylinder mounting nuts
   From inside the cab, locate the mounting fasteners securing the master cylinder to the firewall (verify count and size against Mopar service documentation for this vehicle). Access them from behind the pedal assembly. Remove both mounting nuts while supporting the master cylinder from the engine compartment side to prevent it from falling.
5. 5

   Remove master cylinder
   Carefully pull the master cylinder forward through the firewall from the engine compartment side. The pushrod will come through with the cylinder body. Be prepared for additional brake fluid spillage. Place the old cylinder in a drain pan immediately.
6. 6

   Inspect and clean mounting area
   Inspect the firewall mounting surface and pushrod boot grommet for damage. Clean the mounting area with brake cleaner and a wire brush if necessary. Check that the rubber boot/grommet in the firewall is in good condition and properly seated. Replace if torn or damaged.
7. 7

   Install new master cylinder
   Insert the pushrod of the new master cylinder through the firewall grommet from the engine compartment side. Ensure the pushrod extends properly into the cab area. Align the mounting studs with the firewall holes and press the cylinder firmly against the firewall.
8. 8

   Install mounting nuts
   From inside the cab, thread both mounting nuts onto the studs and tighten evenly by hand first. Then tighten securely in a cross pattern to ensure even pressure. Verify the cylinder is seated flush against the firewall with no gaps.
9. 9

   Connect pushrod to clutch pedal
   Align the pushrod with the clutch pedal arm hole. Insert the pushrod pin through the pedal arm and pushrod connection. Install the retaining clip to secure the pin. Verify the clip is fully seated and the pushrod moves freely with pedal operation.
10. 10

    Connect hydraulic line
    From the engine compartment, remove the cap from the hydraulic line. Carefully thread the line fitting into the master cylinder outlet port by hand to avoid cross-threading. Tighten the fitting with a flare nut wrench to the Mopar-specified torque for the clutch hydraulic line fitting on this vehicle. Do not overtighten, as this can damage the fitting or seat.
11. 11

    Fill brake fluid reservoir
    Fill the brake fluid reservoir to the MAX line with fresh brake fluid matching the specification stamped on the reservoir cap (DOT 3 or DOT 4) from a sealed container. Keep the reservoir filled throughout the bleeding process to prevent air from entering the system.
12. 12

    Bleed clutch hydraulic system
    Locate the clutch hydraulic bleeder for this system. Note that the 2007 Ram 3500 G56 manual uses an internal concentric slave cylinder (CSC) inside the bellhousing; bleeding is performed at the designated bleeder fitting on the hydraulic line rather than an external slave-cylinder bleeder. Attach a clear hose to the bleeder fitting and submerge the other end in a container with clean brake fluid. Have an assistant slowly depress and hold the clutch pedal, open the bleeder, allow fluid and air to escape, then close before releasing the pedal. Repeat until no air bubbles appear. Alternatively, use a vacuum bleeder per manufacturer instructions. Check and top off reservoir level frequently. fluid stream. Alternatively, use a vacuum bleeder following manufacturer instructions. Check and top off reservoir fluid level frequently.
13. 13

    Check for leaks and test operation
    With the system bled, inspect all connections for leaks while an assistant depresses the clutch pedal repeatedly. Check the master cylinder body, hydraulic line connection, and slave cylinder. Wipe all connections dry and observe for fresh fluid indicating leaks. Verify the clutch pedal has firm resistance and returns properly.

Reassembly

1. Reinstall lower dash panel if removed
2. Clean any spilled brake fluid from painted surfaces immediately with water
3. Dispose of used brake fluid properly at an approved recycling center

Verification

• Start engine and verify clutch pedal feels firm with consistent resistance throughout travel
• Verify clutch engages and disengages smoothly without slipping or dragging
• Check brake fluid reservoir level is between MIN and MAX marks
• Test drive vehicle through all gears to confirm proper clutch operation
• Recheck all hydraulic connections for leaks after test drive
• Verify brake warning light is not illuminated on instrument cluster

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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