Clutch Hydraulic Line

Replace the hydraulic clutch line between the master cylinder and slave cylinder on a 2007 Ram 3500 with the 5.9L Cummins diesel engine and manual transmission.

Warnings

Tools required

Parts

• Clutch hydraulic line assembly × 1 — OEM Mopar or equivalent aftermarket
• Clutch slave cylinder dust boot (if damaged) × 1 — Inspect and replace if torn

Fluids

• DOT 3 brake fluid — 0.5 qt

Preparation

1. Park vehicle on level ground and apply parking brake
2. Place wheel chocks behind rear wheels
3. Allow engine and exhaust system to cool completely
4. Raise front of vehicle with floor jack and support securely on jack stands at frame rails
5. Remove belly pan or skid plate if equipped to access transmission area
6. Apply penetrating oil to all hydraulic line fittings and allow to soak for 15-20 minutes
7. Have fresh DOT 3 brake fluid ready from a sealed container

Procedure

1. 1

   Locate and inspect hydraulic line routing
   From under the vehicle, trace the clutch hydraulic line from the master cylinder (mounted on firewall inside engine bay) down to the slave cylinder (mounted on driver's side of transmission bellhousing). Note the routing path, any clips or brackets securing the line, and the condition of the fittings. The line runs along the frame rail and crosses over to the transmission.
2. 2

   Remove hydraulic line from slave cylinder
   Working from underneath the vehicle, locate the hydraulic line connection at the clutch slave cylinder on the transmission bellhousing. Use a flare nut wrench to carefully loosen the fitting at the slave cylinder. Position a catch pan below to collect brake fluid. Once the fitting is loose, unthread it by hand and cap or plug the slave cylinder port immediately to minimize fluid loss and prevent contamination.
3. 3

   Release line from chassis retention clips
   Follow the hydraulic line along the frame rail and identify all retention clips or brackets holding the line in place. These are typically plastic push-type clips or metal spring clips. Carefully release the line from each clip, taking care not to bend or kink the line during removal. Note the exact position of each clip for reinstallation.
4. 4

   Access master cylinder connection in engine bay
   From above, working in the engine bay on the driver's side, locate where the clutch hydraulic line connects to the clutch master cylinder reservoir assembly mounted on the firewall. You may need to remove the air filter housing or intake ducting for better access. Clean the area around the fitting to prevent contamination.
5. 5

   Disconnect line from master cylinder
   Using a line wrench or flare nut wrench, carefully loosen the hydraulic line fitting at the master cylinder. Position rags below to catch any spilled brake fluid. Once loose, unthread the fitting completely and carefully withdraw the line. Cap the master cylinder port immediately with a clean plug or wrap tightly with plastic to prevent fluid loss and contamination.
6. 6

   Remove old hydraulic line from vehicle
   Carefully guide the old hydraulic line out from under the vehicle, following the routing path. Inspect the old line for the failure point - check for cracks, corrosion, rubbing damage, or kinks. This will help prevent future failures by ensuring proper routing of the new line.
7. 7

   Prepare and route new hydraulic line
   Remove protective caps from the new hydraulic line. Compare it to the old line to verify correct length and fitting orientation. Starting from the engine bay, begin routing the new line following the exact path of the original, ensuring it does not contact the exhaust system, steering components, or any sharp edges. The line should have a smooth path with no kinks or tight bends.
8. 8

   Connect new line to master cylinder
   Thread the fitting at the master cylinder end by hand first to ensure proper thread engagement and prevent cross-threading. Once hand-tight, use a line wrench to snug the fitting. Do not overtighten as this can damage the flare fitting - tighten until snug plus approximately 1/4 turn while ensuring the line is not twisting.
9. 9

   Secure line in chassis retention clips
   Working from the engine bay toward the transmission, secure the hydraulic line in all original retention clips and brackets. Ensure the line is positioned exactly as the original with adequate clearance from the exhaust manifold, turbocharger, and steering linkage. Verify at least 1 inch clearance from all hot components.
10. 10

    Connect new line to slave cylinder
    From underneath, guide the slave cylinder end of the line into position. Thread the fitting by hand onto the slave cylinder to ensure proper engagement. Once hand-tight, use a flare nut wrench to snug the fitting. Again, do not overtighten - snug plus approximately 1/4 turn is sufficient.
11. 11

    Fill and bleed clutch hydraulic system
    Remove the cap from the clutch master cylinder reservoir in the engine bay. Fill with fresh DOT 4 brake fluid (or DOT 3/DOT 4 as specified in the owner's manual) to the MAX line. Locate the bleeder screw on the clutch slave cylinder. Attach a clear vinyl tube to the bleeder and route into a catch container. Have an assistant pump the clutch pedal slowly 10-15 times, then hold pressure. Open the bleeder screw 1/2 turn while pedal is held down. Close bleeder before pedal reaches the floor. Repeat until fluid flows clear with no air bubbles. Keep reservoir topped off during bleeding process.
12. 12

    Verify system operation and check for leaks
    With the engine off, pump the clutch pedal multiple times. It should build firm resistance and return smoothly. Start the engine and verify the clutch engages and disengages properly by shifting through all gears. Inspect all fittings at both the master cylinder and slave cylinder for any signs of fluid leakage. Wipe fittings dry and recheck after several clutch pedal applications.

Reassembly

1. Reinstall belly pan or skid plate using original fasteners
2. Reinstall air filter housing or intake ducting if removed
3. Top off clutch master cylinder reservoir to MAX line with DOT 3 brake fluid
4. Lower vehicle from jack stands safely
5. Dispose of old brake fluid and contaminated rags according to local regulations

Verification

• Start engine and verify clutch pedal has firm, consistent feel with no sponginess
• Test clutch engagement by shifting through all gears with engine running - shifts should be smooth without grinding
• Check for fluid leaks at both master cylinder and slave cylinder connections after 5-10 clutch applications
• Road test vehicle to verify normal clutch operation under load
• Recheck clutch master cylinder fluid level after road test and top off if necessary
• Perform final inspection of all hydraulic line connections and routing after first drive

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