Your clutch master cylinder has a reservoir that is full of brake fluid.
This reservoir is connected by hoses to a clutch slave cylinder.
When you step on the clutch, brake fluid passes from the master cylinder into the slave cylinder. So, when you apply pressure the clutch engages which then allows you to change gears.
Hydraulic clutches make it easier to change gears than a cable activated system. Most hydraulic clutches have their own master cylinder. Although there are some cars that use a single master cylinder for the clutch and the brake systems.
When you first open up a hydraulic clutch system you will have to remove any air unwanted air pockets. We do this via a process called bleeding. If there are air pockets present the hydraulic system will not perform to optimum levels. It’s also possible that the slave cylinder may need to be bled as part of the general upkeep of your care.
Here are the steps you’ll need to follow to bleed your car’s clutch slave cylinder.
How To Bleed A Clutch
Step 1: Get the Right Equipment
In order to bleed the clutch slave cylinder you will need the right tools and materials. These include:
- Line wrench or brake bleeder wrench
- Brake fluid, consult your owner’s manual for the right type
- Two feet of clear tubing
- Safety glasses
- Drain Pan
- Paper towel
- Turkey baster or other type of suction tool
- Two safety jacks
Step 2: Locate the Brake Master Cylinder
Now it is time to find the brake master cylinder. First, open up the hood of the car. The brake master cylinder will be on the driver’s side near the firewall.
Step 3: Suck out the Old Brake Fluid
Open the cover of the master cylinder and use a suction tool (a turkey baster will do) in order to remove the old brake fluid and replace it with new fluid. Make sure to check the owner’s manual for your vehicle to determine what type of brake fluid to use.
Step 4: Find the Slave Cylinder
On most cars the slave cylinder will be fixed to the transmission. In other cases it will be inside the transmission. If it is inside the transmission the bleeding valve will still be on the outside. so don’t panic The fastest way to find it is to find the clutch master cylinder and follow the hydraulic line until you’re at the slave cylinder.
In some cases you may need a floor jack along with safety jack stands in order to lift the car and secure the vehicle so that you can get to the slave cylinder. If that is the case exercise great caution and perhaps get a friend or colleague to help stabilize the vehicle.
Step 5: Bleeding the Slave Cylinder
First, put a pan under the cylinder in order to catch all of the brake fluid. Use the wrench to open up the valve and let gravity do its work.
It is important to watch the brake fluid levels of the master cylinder during this process. If the brake fluid in the master cylinder gets too low air can get sucked into the system, which is something we want to avoid.
Step 6: Filling the Slave Cylinder
Next, close the slave cylinder’s bleeder valve. Then attach the tubing to the bleeder. The other end of the tubing will be placed in a water bottle and used to top the master cylinder off with brake fluid.
Step 7: Pumping the Clutch
Get in the driver’s seat and then pump the pedal a dozen or so times in order to build up some pressure. Then hold the pedal down for about ten seconds.
Step 8: Testing the Bleeder
When the clutch is being held down, use your wrench to open up the bleeder -air bubbles leaving the slave cylinder. When the brake fluid stops flowing, close up the bleeder and then release the clutch.
You may need to get a friend or colleague to help you with this phase.
You might to repeat the final steps a few times until only brake fluid comes from the bleeder of the slave cylinder.
It is important to note also that you should never let off of the clutch while the bleeder valve is open as this will suck air into the clutch system.
Here’s a quick run through the process from Jim Bates:
Tips and Warnings
When you are bleeding the clutch often the pedal of the clutch to stay on the car’s floor even when it is released. This is no reason to panic, simply use your hand or your foot to pop the pedal back up to continue the bleeding. When more air is let out and the hydraulic pressure starts to build, the pedal will then come up on its own.
When you are bleeding the slave cylinder you should never let the brake fluid of the master cylinder get very low or air will be sucked into the hydraulic system and you will have to start the entire process all over again.
If you decide to use a vacuum pump in order to bleed your clutch the process is similar to the above. You will simply attach the pump to the open bleeder valve of the slave cylinder. Read the instructions on using the pump.
If you have raised the car off of the ground in order to perform the clutch bleeding process you will want to use a floor jack in order to remove the jack and lower the car to the ground before you start to test the clutch.
When you are pressing the clutch if there is a change in the way it feels, or it stays down, or if there is brake fluid found inside the vehicle you will want to make sure to have a professional mechanic look over the hoses and the master cylinder and have them replaced if necessary.
If there are air pockets found in the fluid or in the hydraulic system, the clutch or brake pedals are going to feel spongy and you also will want to have a mechanic check this out.
Performing routine maintenance on your vehicle is very important and you have just bled the slave cylinder on your vehicle on your own. This is a great way to save money on vehicle maintenance as you will not be paying a professional to perform this service for you. Not only that, you can take a sense of pride in knowing that you can perform this task on your own.
It is important to note that after you have bled your clutch slave cylinder you should pay attention to any changes in the way that it feels when you step on it. If the clutch pedal does not come back up or if you start to notice any brake fluid leaking inside the vehicle, you definitely need to make sure to take the vehicle to a certified mechanic to have it checked out.
Overall, bleeding a clutch slave cylinder is fairly easy and should not take very long. Just make sure that you take your time and look for any air bubbles or other issues during the process.
How did you get on with this? Easy enough or did you struggle?
Let us know below.
Here is another great guide to help you next time.