Clutch Hydraulic System: Service and Repair
STANDARD PROCEDURE-BLEEDING CLUTCH HYDRAULIC CIRCUITNOTE: It is necessary to bleed the clutch hydraulic release system if the system has lost an excessive amount of fluid and has ingressed air into the circuit. Air in the system typically results in a spongy pedal feel, and/or improper clutch release. If air cannot be removed from the system using this procedure, it is necessary to replace BOTH the clutch master cylinder and slave cylinder assemblies.
DIESEL AND TURBO MODELS
NOTE: Due to the angle and design of the Diesel and Turbo hydraulic system components, gravity and pedal bleeding are less effective and less efficient than the reverse fluid injection method (reverse bleeding). Reverse bleeding is recommended for this system, and requires the use of commercially available injection bleeding equipment.
RECOMMENDED PROCEDURE (REVERSE BLEEDING)
1. Remove reservoir cap and inspect fluid level. Top off with DOT 3 Brake Fluid. Actuate clutch pedal briskly at least 50 times. Verify release system function. Repeat. If release system is still inoperative, continue with procedure.
2. Remove reservoir from bracket and empty into collection container.
3. Raise vehicle on hoist.
4. Remove clutch bellhousing access cap to expose system bleed screw (Fig. 5).
CAUTION: Use care not to allow fluid to drain into clutch bellhousing. Excessive fluid will be agitated and sprayed around inside the clutch bellhousing by the rotating flywheel, contaminating the flywheel, disc, and pressure plate, resulting in poor clutch engagement.
5. Using suitable socket/wrench, loosen bleed screw (Fig. 6).
6. Quickly attach hand operated bleed apparatus to bleed screw. Use care not to over-fill reservoir and spill fluid into engine compartment.
7. Operate bleed gun sufficiently to expel air upward through circuit and out of master cylinder reservoir. Fill and empty reservoir three (3) times.
8. Remove bleed apparatus and tighten bleed screw to 7 Nm (62 inch lbs.). Do not over-tighten.
9. Lower vehicle.
10. Top of reservoir and return cap.
11. Verify system operation. Actuate clutch pedal 50 times. If necessary, repeat procedure until road test confirms that shift issues no longer exist.
ALTERNATE PROCEDURE (PEDAL BLEEDING)
1. Remove reservoir cap and inspect fluid level. Top off with DOT 3 Brake Fluid. Actuate clutch pedal briskly at least 50 times. Verify release system function. Repeat. If release system is still inoperative, continue with procedure.
2. Raise vehicle on hoist.
3. Remove clutch bellhousing access cap to expose system bleed screw (Fig. 5).
CAUTION: Use care not to allow fluid to drain into clutch bellhousing. Excessive fluid will be agitated and sprayed around inside the clutch bellhousing by the rotating flywheel, contaminating the flywheel, disc, and pressure plate, resulting in poor clutch engagement.
4. Using suitable socket/wrench, loosen bleed screw (Fig. 6). Immediately install rubber hose to bleed screw to prevent fluid from entering clutch bellhousing. Tighten bleed screw gently with suitable wrench.
5. Lower vehicle.
6. Have helper actuate clutch pedal to floor.
7. Place collection container at end of hose to capture expelled fluid.
8. Using suitable wrench, break bleeder screw loose and tighten to 7 Nm (62 inch lbs.). Do not overtighten.
9. Have helper release pedal, returning it to at-rest position, and then actuate pedal to floor.
10. Break bleeder screw loose and tighten to 7 Nm (62 inch lbs.). Do not over-tighten.
11. Repeat procedure as necessary, keeping master cylinder reservoir full during the process, until air bubbles are no longer visible in collection container.
12. When air bubbles are no longer visible, actuate clutch pedal briskly at least 50 times. Verify release system function and top off fluid as necessary.