How to replace the clutch master cylinder

The clutch master cylinder supplies fluid and pressure to operate the clutch system. Common signs of failure include leaks or loss of pressure.

The clutch master cylinder is the part of the clutch system that helps the operator use the levers. The clutch master cylinder works in the same way as the brake master cylinder. The clutch master cylinder contains a reservoir that stores brake fluid, only of the "point 3" type. The cylinder is connected by hoses to the clutch slave cylinder located on the gearbox.

When you depress the clutch pedal, brake fluid flows from the clutch master cylinder into the slave cylinder, applying the pressure needed to engage the clutch. When you release the clutch pedal, the return spring located on the slave cylinder returns the brake fluid back to the clutch master cylinder.

Part 1 of 10: Know the Signs of Failure

There are three different ways to determine if the clutch master cylinder is bad. The main chamber seal at the rear of the clutch master cylinder will crack and leak brake fluid, causing the reservoir to become low. When the pedal is pushed down, the piston cup inside the cylinder body creates suction and draws in air, causing pressure loss.

The reservoir sleeve will become dry and crack, causing the brake fluid to leak out. When there is too little brake fluid in the reservoir and the bushing is cracked, air will be sucked in, resulting in a drop in pressure.

The piston cup seal sloshes into the clutch master cylinder, causing the brake fluid to move back and forth. This eliminates the movement of fluid to the working cylinder, which leads to loss of supply.

Pascal's law states that all areas containing fluid are incompressible and all pressures are the same anywhere. Applying a larger dimension will have more leverage than a smaller dimension.

Pascal's law plays a big role in the hydraulic clutch system. As long as there is fluid at the proper level in the system, force is applied and all air is released, the hydraulic clutch system will work properly.

However, when air is introduced into the system, the air becomes compressible, allowing the fluid to stop. If there is little fluid, or if the applied force is minimal, then the force will be low, causing the slave cylinder to operate about half way. This will cause the clutch to slip and not engage gears, and the clutch will not release properly.

Part 2 of 10: Checking the Condition of the Clutch Master Cylinder

Step 1: open the hood. Look at the car's firewall and find where the brake master cylinder is.

The clutch master cylinder will be next to it.

Step 2: Inspect the clutch master cylinder for brake fluid leaks.. If brake fluid is present, open or unscrew the reservoir cap and check the fluid level.

If the level is above the reservoir, then the hydraulic clutch system has been overfilled. If the reservoir was low, then there was an external leak in the hydraulic clutch system.

Step 3: Check the clutch master cylinder fasteners.. Visually check that all lock nuts are present.

Try moving the clutch master cylinder by hand. He should be firm and unable to move.

Part 3 of 10: Car preparation

Necessary materials

• Jack
• Jack stands
• Wheel chocks

Step 1: Park your vehicle on a level, firm surface.. Make sure the transmission is in park (for automatic transmission) or 1st gear (for manual transmission).

• Attention: Only for vehicles with AWD or RWD transmission.

Step 2: Install wheel chocks around the rear wheels.. They will stay on the ground.

Apply the parking brake to block the rear wheels from moving.

Step 3: Raise the car. Jack up the vehicle at the indicated points until the wheels are completely off the ground.

Step 4: Install Jacks. The jack stands should pass under the jacking points, then lower the vehicle onto the jack stands.

For most modern cars, the jack stand attachment points are on a weld right under the doors along the bottom of the car.

Part 4 of 10: Removing the Integral Clutch Master Cylinder

Necessary materials

• Hex key set
• socket wrenches
• brass punch
• Switch
• Clasp remove
• Ratchet with metric and standard sockets
• needle nose pliers
• Torque bit set
• Wrench
• Vampire pump and bottle

Step 1: Get a Vampire Pump with a Bottle. Remove the reservoir cap from the cylinder reservoir.

Use the vampire pump and collect all the brake fluid from the reservoir. After removing all the brake fluid, close the reservoir cap.

• A warning: Do not allow brake fluid to come into contact with the paint. This will cause the paint to peel and flake off.

Step 2: Remove the hydraulic line from the clutch master cylinder.. Be sure to put a plastic bag on the end of the hose with a rubber band so that the brake fluid does not leak out.

• Attention: Do not bend the hydraulic line as it may crack or break.

Step 3: Remove the cotter pin. Enter the driver's cab and remove the cotter pin from the anchor pin.

It can be found on a fork attached to the clutch master cylinder push rod with a pair of needle nose pliers.

Step 4: Remove the anchor pin from the pusher yoke..

Step 5: Remove the retaining nuts from the clutch master cylinder..

Step 6: Remove the clutch master cylinder from the firewall.. Make sure the side of the cable attachment is facing up to prevent dripping of brake fluid.

Place the clutch master cylinder in the bag.

Part 5 of 10: Removing the hydraulic clutch assembly

Necessary materials

• Hex key set
• socket wrenches
• brass punch
• Switch
• Drip tray
• Clasp remove
• Ratchet with metric and standard sockets
• needle nose pliers
• Torque bit set
• Wrench
• Vampire pump

Step 1: Remove all brake fluid. Remove the reservoir cap from the cylinder reservoir.

Use the vampire pump and collect all the brake fluid from the reservoir. After removing all the brake fluid, close the reservoir cap.

• A warning: Do not allow brake fluid to come into contact with the paint. This will cause the paint to peel and flake off.

Step 2: Remove the cotter pin. Enter the driver's cab and remove the cotter pin from the anchor pin on the bracket.

It will be attached to the clutch master cylinder push rod with a pair of needle nose pliers.

Step 3: Remove the anchor pin from the pusher yoke..

Step 4: Remove the retaining nuts from the clutch master cylinder..

Step 5: Locate the hydraulic line connecting the clutch master cylinder to the slave cylinder.. Remove all mounting insulated clamps that secure the hydraulic line to the vehicle.

Step 6: Grab the creeper and get under the car.. Remove the two bolts or clamp that secure the slave cylinder to the gearbox.

Step 7: Remove the entire system. Very carefully remove the entire system (clutch master cylinder, hydraulic line and slave cylinder) through the engine compartment.

• A warning: Do not bend the hydraulic line, otherwise it will break.

Part 6 of 10: Prepare the integrated clutch master cylinder.

Necessary materials

• Hex key set
• socket wrenches
• brass punch
• Switch
• Clasp remove
• Ratchet with metric and standard sockets
• needle nose pliers
• Torque bit set
• Wrench

Step 1: Remove the clutch master cylinder from the package.. Visually inspect the cylinder for damage.

Make sure the seal is at the back of the cylinder body.

Step 2: Take the clutch master cylinder and place it in a vise.. Clamp until the cylinder stops moving.

Step 3: Install the hydraulic line for the tube. Install the tube in the hole into which the hydraulic line will be screwed.

Remove the tank lid and place the bath in the tank.

Step 4: Fill the reservoir with brake fluid.. Leave 1/4 inch at the top empty.

Step 5: Use a brass punch as an extension to fill the cylinder.. Slowly bleed the cylinder from the back of the clutch master cylinder.

Make sure that the brake fluid gets from the transparent tube into the reservoir. This fills the cylinder and removes all the air inside the cylinder.

Part 7 of 10: Preparing the hydraulic clutch assembly

Necessary materials

• Hex key set
• socket wrenches
• brass punch
• Switch
• Clasp remove
• Ratchet with metric and standard sockets
• needle nose pliers
• Torque bit set
• Wrench

Step 1: Remove the clutch master cylinder from the package.. Visually inspect the cylinder for damage.

Make sure the seal is at the back of the cylinder body.

Step 2: Place the clutch master cylinder and slave cylinder assembly in a vise.. Clamp until the clutch master cylinder stops moving.

Place the slave cylinder on a stool or other support.

Step 3: Remove the bleed screw. Place a pan under the slave cylinder and remove the air bleed screw.

Step 4: Fill the reservoir with brake fluid.. Leave 1/4 inch at the top empty.

Step 5: Use a brass punch as an extension to fill the cylinder.. Slowly bleed the cylinder from the back of the clutch master cylinder.

Make sure that brake fluid does not leak from the slave cylinder. You will have to fill the reservoir approximately three times to fill the entire system. This fills the cylinder and removes most of the air from the cylinder, hydraulic line, and slave cylinder.

When a continuous stream of brake fluid flows out of the bleed hole on the slave cylinder, stop and install the bleed screw.

Step 6: Hire a Helper. Have an assistant use a brass punch and pump up the cylinder.

You will then need to loosen the air bleed screw so the air can escape as the brake fluid flows out.

• Attention: You may need to loosen the bleed screw several times during pumping cycles to remove all air from the hydraulic system.

Step 7: Make sure the bleeder screw is tight. Fill the reservoir with brake fluid up to the fill line and install the reservoir cap.

Part 8 of 10: Installing the Integral Clutch Master Cylinder

Necessary materials

• Hex key set
• socket wrenches
• brass punch
• Switch
• Drip tray
• Clasp remove
• Ratchet with metric and standard sockets
• needle nose pliers
• Torque bit set
• Wrench

Step 1: Install the clutch master cylinder into the firewall.. Be sure to keep a clear tube to prevent dripping of brake fluid.

Step 2: Install Mounting Nuts. Get into the cab of the car and install the mounting nuts on the clutch master cylinder.

Tighten them according to the specifications on the package. If no instructions are available, finger-tighten the bolts 1/8 turn.

Step 3: Install the anchor pin. Install it in the pusher bracket.

• Attention: Do not depress the clutch pedal. The force can cause the clear tube to come out of the clutch master cylinder and brake fluid to leak out.

Step 4: Install the new cotter pin. It must be installed in the anchor pin on the bracket attached to the push rod of the clutch master cylinder using needle nose pliers.

• A warning: Do not use the old cotter pin due to hardening and fatigue. An old cotter pin may break prematurely.
  
  

Step 5: Take a pan and place it under the clutch master cylinder.. Remove the transparent tube and install the hydraulic clutch line.

• A warning: Do not cross the hydraulic line when installing it. Brake fluid will leak out.

Step 6: Bleed the hydraulic line to the cylinder.. Have an assistant press and hold the clutch pedal. Loosen the line and bleed the air from the system.

You may need to perform the bleeding procedure a couple more times to remove all the air. Tighten the string tightly.

Step 7: Remove the reservoir cap. Add brake fluid to full line.

Part 9 of 10: Installing the hydraulic clutch assembly

Necessary materials

• Hex key set
• socket wrenches
• brass punch
• Switch
• Drip tray
• Clasp remove
• Ratchet with metric and standard sockets
• needle nose pliers
• Torque bit set
• Wrench
• Vampire pump and bottle

Step 1: Install the whole system. Very carefully install the entire system (clutch master cylinder, hydraulic line, slave cylinder) down through the engine compartment.

• A warning: Do not bend the hydraulic line as it will break.

Step 2: Install the Slave Cylinder. Go under the car and install the slave cylinder by hand-tightening the bolts and then 1/8 turn to tighten the clamp.

Step 3: Install the clutch master cylinder into the firewall..

Step 4: Install Mounting Nuts. Get into the cab of the car and install the mounting nuts on the clutch master cylinder.

Tighten them according to the specifications on the package. If no instructions are available, finger-tighten the bolts 1/8 turn.

Step 5: Install the anchor pin into the pusher bracket..

Step 6: Install the new cotter pin. Do this in the anchor pin on the bracket attached to the clutch master cylinder pushrod using a pair of needle nose pliers.

• A warning: Do not use the old cotter pin due to hardening and fatigue. An old cotter pin may break prematurely.

Step 7: Install All Insulated Mounting Clamps. Return to the engine bay and install all of the insulated mounting clamps that secure the hydraulic line to the vehicle.

• Attention: Be aware that the hydraulic clutch system assembly is already primed and filled with fluid and all air has been purged from the system.

Step 8: Raise the car. Raise the vehicle at the indicated jack points until the wheels are completely off the ground.

Step 9: Remove Jack Stands. Move them away from the car.

Step 10: Lower the car so that all four wheels are on the ground.. Pull out the jack and set it aside.

Step 11: Remove wheel chocks from rear wheels.. Set them aside.

Part 10 of 10: Checking the New Clutch Master Cylinder

Step 1: Make sure the transmission is in neutral.. Turn on the ignition key and start the engine.

Step 2: Press the clutch pedal. Move the gear selector to the option of your choice.

The switch should easily enter the selected gear. Turn off the engine when you are done with the test.

Step 3: Test drive the car. Drive your car around the block.

• Attention: During the test drive, shift gears from first to higher gear one at a time.

Step 4: Press the clutch pedal down. Do this when shifting from the selected gear to neutral.

Step 5: Press the clutch pedal down. Do this when moving from neutral to another gear selection.

This process is called double clutching. This ensures that the transmission draws little to no power from the engine when the clutch is properly disengaged. This process is designed to prevent clutch damage and transmission damage.

If you don't hear any grinding noise and shifting from one gear to another feels smooth, then the clutch master cylinder is installed correctly.

If you cannot engage the transmission in any gear without a grinding noise, or if the clutch pedal does not move, this may indicate an additional diagnosis of the clutch pedal assembly or a possible transmission failure. If the problem persists, you should seek the assistance of one of our certified mechanics who can inspect the clutch and transmission and diagnose the problem.