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Service Procedures for Hydraulic Clutch Release Systems

Follow the advice below for several methods of clutch hydraulic release system services

Hydraulics part


Master Cylinder – Removal and Installation

Mast cyl

Master cylinders are a long lasting part, but they won’t last forever. When this part wears, you’ll have clutch pedal issues. When it's time to replace your master cylinder, buy one here and then:

1. Disconnect master cylinder pushrod from the clutch pedal. Inspect and replace pedal pin bushing if worn or damaged.

2. If the safety interlock switch is fitted to the pushrod, disconnect the switch connector.Note: Some Ford Aerostars require the pushrod removal from the master cylinder before it can be removed.

3. Using a 3mm punch, drive out the retaining pin that holds the hydraulic tube to the master cylinder. Be careful not to damage the master cylinder body.Note: On some vehicles the hydraulic line will have an in-line tube connector. It can be disconnected using the hydraulic line Quick Connect tool.

4. On vehicles with a remote reservoir, remove the fasteners holding it to the front of the dash.

5. Remove the two fasteners retaining the master cylinder assembly.

Note: On some vehicles a "Twist and Lock" type of attachment is used to secure the master cylinder to the front of the dash. To remove the master cylinder with this type of attachment, the master cylinder body must be rotated. Rotate approximately 45 degrees clockwise (except for Saturn vehicles, which require a counterclockwise rotation). The front of the dash or bracket is keyed so the master cylinder can only be reinstalled with the correct body and reservoir orientation. When reinstalling a master cylinder with this type of attachment be careful not to over rotate the master cylinder.

6. Carefully remove the master cylinder from the front of the dash.

7. For re-installation, complete steps 1 through 6 in reverse order.

8. Bleed the master cylinder per the Hydraulic Bleeding instructions.

Internal Concentric Slave Cylinder – Removal, Installation, and Bleeding

Slave cyl1

The slave cylinder is another part that isn’t made to last forever. Most people choose to replace it during each clutch replacement. Sometimes, it needs to be replaced sooner. Get your replacement OE slave cylinder here.

1. Disconnect the hydraulic tube coupling at the transmission with the quick disconnect tool. Do this by sliding the white plastic sleeve toward the slave cylinder.

2. Remove the transmission per your service manual.

3. Remove the bolts retaining the slave cylinder to the transmission.

4. Remove the slave cylinder from the transmission.

5. Clean the transmission input shaft and install the new slave cylinder. Make sure the slave cylinder is installed flat against the transmission mounting surface.

6. Install the slave cylinder attaching bolts and tighten to the vehicle’s torque specs. Check to make sure the slave cylinder is not cocked.

7. Re-install the transmission.

8. Inspect the hydraulic tube coupling for damage and contamination. Replace the “O” ring and lube with clutch fluid.

9. Reconnect the hydraulic tube by inserting the male coupling into the female coupling. Make sure the coupling is secure.

10. Carefully clean the top and sides of the reservoir before opening. This will prevent contamination of the system with dirt, water, and other foreign material.

11. Remove the reservoir cap.

12. Remove the reservoir diaphragm when checking or adding fluid.

13. Fill the reservoir with new clutch hydraulic fluid or an approved DOT 3 brake fluid.

Note: Do not use fluid that has been bled from a system to fill the reservoir, as it may be contaminated. Never use transmission fluid, motor oil, power steering fluids, or any mineral oil fluids.

14. Pump the clutch pedal 15-20 times, making sure the pedal is allowed to return completely between strokes.

Note: Check and fill the reservoir as needed while bleeding to prevent air from being drawn into the system.

15. Depress the clutch pedal and hold.

16. Slowly open the bleed screw located on the concentric slave cylinder and allow any trapped air to escape.

17. Close the bleed screw and release the clutch pedal. Do not over tighten the bleed screw.

18. Repeat Step 14 until all the air is pumped out of the concentric slave cylinder and clean. There should be bubble free clutch fluid visible in the reservoir.

19. If clutch disengagement is not satisfactory, repeat the bleeding procedure. Under normal usage, small amounts of air will eventually work its way out of the system.

External Slave Cylinder - Removal and Installation

Slave Cyl2

The master cylinder pushrod should be disconnected from the pedal before removing the slave cylinder. If not disconnected prior, permanent damage to the slave cylinder will occur.

Some external slave cylinders do not have bleed screws. These cylinders must be filled with clutch hydraulic fluid before they are installed.

All slave cylinders are shipped with a plastic pushrod-retaining strap. This strap retains the pushrod during shipping and also provides a nonmetallic end for the pushrod. This helps prevent wear and squeaks when the clutch is actuated. Make sure the pushrod-retaining strap is in place and secure when the slave cylinder is reinstalled to the vehicle. The pushrod retaining strap bands are designed to break during the first clutch application.

Get your replacement slave cylinder here and follow the instructions for removal and replacement.

1. Using a 3mm punch, drive out the retaining pin that holds the hydraulic tube to the master cylinder. Be careful not to damage the master cylinder body.

Note: On some vehicles the hydraulic line will have an in-line tube connector that can be disconnected. Do this using the hydraulic line quick disconnect tool.

2. Remove the bolts/retainer holding the slave cylinder to the transmission.

3. Remove the slave cylinder from the transmission.

4. Install the new slave cylinder. Make sure the pushrod is securely seated in the cup end of the clutch release lever.

5. Install the slave cylinder retainer or attaching bolts and tighten per the vehicle requirements.

6. Inspect the hydraulic tube coupling for damage and contamination. Replace the “O” ring and lube with clutch fluid.

7. Insert the tube fitting into the slave cylinder fluid port and replace the retaining pin. Be careful not to damage the slave cylinder body.

8. If applicable, reconnect the hydraulic tube. Do this by inserting the male coupling into the female coupling on the adjoining tube or slave cylinder. Make sure the coupling is secure.

9. Bleed the slave cylinder per instructions.

Clutch Hydraulic Line – Removal and Installation

Clutch line

This line is usually replaced with the rest of the hydraulic system.

1. Before removing the hydraulic line assembly from the vehicle, inspect the tube and take note of the tubes routing. When reinstalling the new tube it must be routed exactly as the tube being replaced.

2. Using a 3mm punch, drive out the pin that holds the hydraulic tube to the master cylinder and the slave cylinder body. Be careful not to damage the master cylinder or slave cylinder body.

Note: On some vehicles the hydraulic line will have an in-line tube connector that can be disconnected using a quick disconnect.

3. Lubricate the two small quad seals with the clutch hydraulic fluid and install on the new tube fittings.

4. Reinstall the new tube assembly. Pay careful attention to the tube routing. Do not kink tube or allow the tube to be closer than 4 inches to any engine exhaust manifold.

5. Insert the tube fitting into the master cylinder fluid port and replace the retaining pin. Be careful not to damage the master cylinder body.

6. Insert tube fitting into slave cylinder fluid port and replace the retaining pin. Be careful not to damage the slave cylinder body.

7. Where applicable, reconnect the in-line tube connector.

8. Bleed the system per the applicable hydraulic bleeding Procedures.

Hydraulic Bleeding of Master Cylinders and External Slave Cylinders with Bleed Screws

1. Clean the top and sides of reservoir before opening to prevent contamination of the system.

2. Remove the reservoir cap.

3. Remove the reservoir diaphragm.

4. Fill the master cylinder reservoir with new clutch hydraulic fluid or an approved DOT 3 brake fluid only!

5. Depress the clutch pedal and hold it down.

6. Open the bleed screw on the slave cylinder to let air and clutch fluid escape.

7. Close the bleed screw and release the clutch pedal. Don’t over tighten the bleed screw.

8. Repeat steps 5 thru 7 until all the air is out and the clean clutch fluid is visible.

Note: Check and refill the reservoir as needed while bleeding the system to prevent air from being drawn into the system.

After bleeding the system, pump clutch pedal several times. If clutch engagement is not satisfactory, repeat the bleeding procedure. Also, try bleeding the system using the procedure for slave cylinders without bleed screws.

Hydraulic Bleeding of Master Cylinders and External Slave Cylinders without Bleed Screws

1. Push the slave cylinder pushrod in and disconnect both retaining bands of the retaining strap. Release the push rod and allow it to fully extend. Do not cut or discard the retaining strap.

2. Tip the slave cylinder up at approximately 45 degrees. Pour clutch hydraulic fluid into the hydraulic port until all the air it out.

3. With the slave cylinder still tipped up, insert the hydraulic line in to the slave cylinder hydraulic output port. Replace the small rubber seal on the end of the metal tube connector and lubricate it with clutch fluid. Insert the retaining pin and drive it in with a drift punch.

4. Hold the slave cylinder vertically with the pushrod facing the ground. Hold the pushrod against the palm of your hand in a position that allows the slave cylinder to be lower than the master cylinder.

5. Slowly depress the pushrod into the slave cylinder bore. Push approximately a little under 1” while watching the master cylinder reservoir for air bubbles. Stroke the slave cylinder in this manner until air bubbles are no longer entering the reservoir, about 10 – 15 strokes.

6. With the master cylinder reservoir cap removed, slowly push the slave cylinder pushrod back in. Now, reconnect the two bands of the retaining strap. The slave cylinder is now ready to be installed in the vehicle.