How To Bleed Clutch Master Cylinder [5 Easy Steps]

The clutch master cylinder is a major component of a manual transmission vehicle. The manual vehicles require the driver to operate a clutch when stopping or changing speeds. The purpose of the clutch master cylinder is to generate hydraulic power which allows the clutch to function properly. It happens through hoses that connect the clutch master cylinder and clutch slave cylinder.

Over time, air can enter the system due to various reasons and it may require bleeding. Here is how to bleed clutch master cylinder easily.

Why Do You Need To Bleed Clutch Master Cylinder?

As the clutch system of the car is a hydraulic-based system, as a part of general maintenance, the system routinely requires bleeding. Here are the main reasons for bleeding.

1. Hydraulic System Not Leak Tight

The clutch system is basically a hydraulic circuit, it is very essential that it is leak-free. If the hydraulic circuit is leaking, then it is highly possible that air will find a way into the system.

If the air has entered the system, then in order to efficiently work, it is very necessary that the clutch master cylinder needs to be bleed.  Without doing so, proper engagement and disengagement of clutch would not happen. It will also cause rough shifting.

2. Bad Hydraulic Cylinder

The clutch system has two hydraulic cylinders i.e master and slave cylinder. If any of these cylinders have developed a leak or have worn out,  then it will require a change of master or slave cylinder. After installing any new component in the brake system, it is essential that the system should be bleed.

3. General Fluid Maintenance

The dot 3 or dot 4 fluid that is present in the clutch circuit is very hygroscopic in nature. With time and age, the clutch fluid gets bad and becomes inefficient. The fluid must be changed at the regular service interval. Knowledge about how to bleed clutch master cylinder is important. The procedure included to do that requires the whole clutch system to be bleed. It will include bleeding of the clutch master cylinder.

4. Manual Transmission Service

As a part of the manual transmission service, sometimes the whole transmission has to be taken out of the car. When the transmission is taken out, the clutch system is discontented and it has to be bleed again when the transmission is outback. It essentially requires service or bleeding of the clutch master cylinder.

How To Bleed Clutch Master Cylinder In A Manual Car?

To properly bleed the clutch master cylinder, you’ll need a partner. You’ll also need some new hydraulic fluid. The main procedure of bleeding the clutch master cylinder is as follows-

1. The Initial Preparations

Firstly, you need to locate the clutch slave cylinder of your vehicle. Once you’ve found the slave cylinder, locate its bleeder valve. This should look like a small nut on the end which usually has a diameter of about 8mm.

The nut is often covered by a rubber nipple to keep dirt and debris out. A bleeding tube should be attached to the bleeder nipple. Use a jar below to catch any excess fluid.

2. Open The Bleeder Valve To Start Purging

Apply firm pressure to the clutch pedal in the cabin of your vehicle. Press down the clutch pedal all the way until it reaches the floor. Use a wrench (8mm) on the slave cylinder bleeder valve to loosen it up. Keep loosening the valve until air comes out. Moments later, you should start seeing hydraulic fluid “bleeding” out of that. Make sure you place a container down so that the fluid can fall into it.

Note that it is best to use a flare nut wrench for clutch and brake bleeding. These wrenches are designed to put as much surface area as possible on the bleeder screw so you minimize the chance of stripping the nut.

3. Repeat The Pumping Cycle

Keep repeating the cyclin of pumping till you start to see the clear new hydraulic fluid coming out of the bleeder valve. Once you see clear fluid, tight back the bleeder valve while the clutch pedal remains depressed. Releasing the clutch before the bleeder screw is tightened could suck air back into the system.

Once tightened, take pressure off the clutch pedal until it reaches its regular position. See if there is still enough fluid in the master cylinder. Add more as needed. If the fluid level drops after the bleeder screw have been tightened, you may have a leak somewhere in the system. The leak should be attended to.

4. Top Of The Master Cylinder

Topping off the reservoir in how to bleed clutch master cylinder process is very important. Slowly release the clutch pedal until it is returned to its normal position. Go to the master cylinder and open the top of the brake fluid reservoir. Take your hydraulic fluid and pour it into the reservoir until the fluid reaches the “Full” line. Try not to add so much that it overfills.

5. Test Clutch Pedal

After the bleeding has been completed, testing the clutch in process is important. Do it by starting the vehicle and stepping on the clutch pedal yourself. The pedal should feel firm and smooth to press. Also, change gears to see if they’re smooth or slippery. If they’re smooth, then everything is fine now.

How Much Will It Cost To Bleed Clutch System?

The cost of bleeding the clutch system is not that much. It should not cost you more than 100-200$ depending upon the make and model of the car. You can also buy those vacuum bleeders for 200$. With that, you can do the bleeding job at home by yourself. If some component needs to be replaced along with bleeding, then it can cost in the range of 100-300$.


If you fully understand the process of How to bleed clutch master cylinder, then  is not a that difficult job. What makes it difficult is that it requires two persons to fully do the job effectively. In case you do not have any budget issues, then you should invest in those vacuum bleeding systems. With those, you can easily do the job alone, without any help.

If you still feel that you have any questions regarding the whole procedure, then feel free to comment down below.

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