How to Bleed a Clutch: Master and Slave Cylinders

A failing or bad hydraulically operated clutch system typically shows the driver a few signs of wearing down, whether it’s a leak or air in the clutch line, or abnormal pedal behavior. These are all signs not to be ignored; some can be easily fixed by bleeding the clutch.

Gravity bleeding your car’s clutch is a relatively straightforward process that can be done by two people—the recommended or by one person. We’ll show you how to gravity bleed a clutch, so stick around to learn more.

How to gravity bleed a Clutch

The hydraulic clutch

The basic hydraulic linkage clutch in a manual transmission comprises a couple of components, i.e., the clutch disc, the flexible clutch hose, the master, and slave cylinders. The master cylinder has a clutch or brake fluid reservoir connected to the slave cylinder via a flexible clutch hose.

Whenever you actuate the clutch, the master cylinder displaces the hydraulic fluid with its pushrod through the flexible clutch hose to the slave cylinder. The slave cylinder can then engage the clutch fork, which disengages the clutch allowing you to change gears or stop.

A hydraulic linkage clutch system offers several benefits compared to its mechanical linkage counterpart. It provides a smoother pedal feel, comes in a small form factor, is self-adjusting, and can be easily installed.

However, its prone to developing leaks, wearing down, and allowing air inside the system, which makes it malfunction. What’s more, if you had either of the components replaced recently, i.e., the master cylinder, slave cylinder, or flexible hose, you may have let air seep through, contaminating the hydraulic fluid.

When air enters the hydraulic system, it creates compressible air bubbles. These compressible air bubbles absorb some of the hydraulic pressure generated when the clutch is engaged, limiting the pressure that reaches the slave cylinder.

Consequently, the slave cylinder pushrod doesn’t get enough pressure to travel the required length to disengage the clutch disc. Gravity bleeding your clutch is a great way to remove the air in your hydraulic linkage clutch and restore its normal function.

Signs of clutch bleeding

If you’ve been having trouble shifting gears, noticed an abnormal pedal behavior, or your engagement point has dropped, chances are you’ve got air in your hydraulic clutch. It’s important to check your clutch as part of your routine car servicing.

It would be best if you also remembered to get it replenished after every few years to keep your clutch in top condition. But if you’ve been experiencing either of the above issues, then sit tight as we walk you through the gravity bleeding technique.

Step One: Safety and Supplies

Brake fluid is known to be corrosive to paint and irritates the eyes and the skin. You must avoid direct contact with it and wear the necessary protective equipment.

These include goggle-type safety glasses and a pair of latex or neoprene gloves. You also want a rug and an engine cleaner to help clean up any messes.

The engine cleaner removes stubborn dirt or debris around the master cylinder’s reservoir. For tools, you’ll need to get a line wrench–typically a 10 or 8-mm wrench, and a car jack plus two jack stands will do the trick.

You’ll also need a see-through rubber tubing that’s a foot to two feet long and a collection container, bucker, mason jar, or empty soda bottle—take your pick. Ask a friend to come and help gravity bleed the clutch and get brake fluid specific to your car—refer to the manual.

Lastly, you’ll need a suction tool; we recommend using your everyday turkey baster and a funnel. It’s worth noting that some vehicles share the master cylinder with both the brake and the clutch systems; while most cars have a dedicated master cylinder, we’ll be covering the latter.

Step Two: Find the master cylinder’s reservoir

The master cylinder can be found in the engine bay on the driver’s side next to the firewall. Once you’ve found it, uncap it and store the cap somewhere safe since we won’t be using it for a while.

Using your suction tool, in our case, a turkey baster, suck out the old brake fluid in the master cylinder from the reservoir. Once you’re done, using your rug, clean the area around the cap and remove any stubborn debris or dirt with your engine cleaner leaving it nice and clean.

Then fill it up with your vehicle’s brake fluid to the fill point using the funnel to avoid any corrosive hydraulic fluid on your car’s paint.

Step Three: Find the bleeder nipple

Jack up the front of your car, ensure it’s securely supported by the jack stands, and use the designated manufacturer jacking positions. Once the car’s jacked up, you can easily find the slave cylinder, usually located on the driver’s side next to the transmission system.

The bleeder nipple is found on the slave cylinder and looks like a bolt with a rubber cap sticking out of it. Remove the rubber cap and connect your rubber tubing to the nipple and direct it to your collection container.

Step Four: Let gravity take over

Using your 8mm or 10mm wrench, slightly open the bleeder screw and watch as the hydraulic fluid drains through the rubber tubing into the bucket. Leave the bleeder screw open and let gravity do its work—that’s why it’s called gravity bleeding, for about three minutes.

While bleeding, you must watch for the hydraulic fluid levels in the master cylinder’s reservoir. This is because if it gets too low, air may be sucked into the hydraulic system, and you’ll have to bleed the clutch again.

The brake fluid drains quickly, especially if air bubbles are in the clutch line. In such a situation, you want to maintain the clutch fluid at the fill line by topping it up when it gets low, and soon enough, you’ll notice a color change which is an indicator of new clutch fluid.

Step Five: Close up shop

Once the new clutch fluid drips through and there are no more air bubbles, you’ve successfully gravity-bled your clutch. It’s time to tighten the bleeder screw, remove the clear hose, and cap the nipple.

All that’s left is for you to jack the car up, remove the jack stands, fill up the master cylinder’s reservoir to the fill line, close the cap, and you’re good to go.

You should now have a smoother feeling and a much firmer clutch pedal. The biting point should be restored, but there’s only one way to find out, start the engine and get moving.

We hope you liked our guide on gravity bleed a clutch, and don’t forget to let us know your thoughts in the comment section below.

3 Clutch Bleeding Symptoms you should never ignore

Most late-model manual transmission vehicles activate their clutch system using their hydraulically actuated master and slave cylinder system. By depressing the clutch pedal, the piston in the master cylinder is forced down its bore, pushing the hydraulic fluid down through a tube to the slave cylinder.

Regardless of the type of slave cylinder your vehicle is fitted with, it can propagate the pressure to its piston, which disengages the clutch. A hydraulically operated clutch system has plenty of benefits, from decreasing pedal effort to using failure-proof components.

Conversely, hydraulically actuated clutches are prone to developing issues, especially in the master-to-slave pipeline. From failing to maintain the needed pressure for activation to leaking hydraulic fluid to drawing in the air—some of which are clutch bleeding symptoms that lead to drivability problems.

Some of the drivability issues that arise from these symptoms include finding it hard to shift gears and a noticeably awkward clutch pedal behavior.

On the one hand, these symptoms may signal the end of the expected service life of your master and slave cylinders, especially in a high mileage vehicle, and will need to be replaced. However, if either component leaks or is damaged, it should be replaced before a new clutch component is installed.

On the other, as we’ve mentioned above, these could be clutch bleeding symptoms and may be fixed by bleeding your clutch’s master or slave cylinder.

If you’ve been wondering what happens if you have air in your clutch or “Do I need to bleed my clutch?” stick around as we delve into a few common clutch bleeding symptoms.

Hard to change gears

A failing or bad clutch master cylinder tends to make shifting gears difficult. Being a hydraulically actuated system, its prone to developing internal leaks, making it difficult to perpetuate the required hydraulic fluid pressure to the slave cylinder.

A problematic clutch master cylinder cannot properly transfer the pressure from a depressed clutch pedal to its hydraulic fluid, making it hard to disengage the clutch. It may even lead to gears grinding when you attempt to shift gears and disjoin your transmission.

The complex components and intricate working mechanism of the transmission system make repairs costly, so don’t ignore it. While the transmission can also be the culprit for your difficulty in shifting gears, the usual suspect is the clutch.

Contaminated or Low clutch fluid

Our next clutch bleeding symptom is contaminated clutch fluid. Your vehicle’s clutch fluid is the driving force behind your hydraulic clutch system.

The clutch fluid is the hydraulic fluid that can propagate the mechanical pressure on the clutch pedal to disengage the clutch effectively. Without it, you wouldn’t be able to engage or disengage the clutch, and vital components of the clutch system could be damaged in the process.

Your vehicle’s clutch fluid is stored in a master cylinder, and on actuating the clutch pedal, it propagates the pressure to the slave cylinder, which engages the clutch. Over time it can get dirty or contaminated and will need to be replaced, a symptom of clutch bleeding.

There are a variety of ways your clutch fluid can get contaminated:

Problematic valve or seal

Your clutch’s master and slave cylinders are fitted with valve seals designed as one-way sealing devices containing the pressurized hydraulic fluid.

With failing or bad valve seals, the clutch master cylinder cannot generate the required pressure to activate the clutch.

What’s more, broken valve seals allow contaminants to enter the master cylinder’s bore, contaminate the clutch fluid, and allow it to leak.

Problematic dust boot

Most of the seals in the clutch system are made from rubber, including the dust boot. Over time, your clutch’s dust boot can harden or rupture, which will allow the entry of water and dirt in your master or slave cylinders bore and contaminate the clutch fluid.

However, it’s a clutch bleeding symptom that can be easily avoided with vigilance, i.e., by regularly inspecting your clutch’s dust boot.

Wear and tear

Naturally, like all other parts of your vehicle, your clutch fluid is susceptible to wear and tear, though not in the traditional sense. Like brake fluid, it picks up water, dirt, and other contaminants over time and becomes dirty.

A classic clutch bleeding symptom that is easily mitigated by routinely changing the fluid each year. However, if you notice you’re regularly losing clutch fluid or changing it, an overhaul of the clutch system for inspection may be necessary to check for leaks.

Leaking clutch fluid

Everything from water, oil, and dirt can get into your clutch’s fluid and contaminate it. Leaking clutch fluid is another common bleeding symptom and will make it hard for you to shift gears. You may even notice the clutch sticking to the floor when you depress the pedal.

Abnormal Clutch Feel

Our last clutch bleeding symptoms manifest themselves as an abnormal feeling when you depress the clutch pedal. It’s also a common sign of a failing or defective master cylinder since any issues that develop in its tandem configuration will typically influence how your pedal feels.

What’s more, a leakage in either the master or slave cylinder may affect the feel of the clutch pedal, giving it a spongy or mushy feel. You may also notice the clutch sinking to the floor when you depress it, but this typically happens when there’s a severe leak in the master cylinder.

Your vehicle’s clutch fluid is the lifeblood of your clutch, and you must be proactive by constantly checking for leaks and replenishing contaminated brake fluid. Being constantly vigilant for common clutch bleeding symptoms is a great way to save on costly transmission repairs and keep your vehicle’s overall drivability in top shape.

How to bleed a clutch master cylinder Honda Civic

Bleeding a Honda Civic clutch refers to purging your hydraulic linkage clutch and involves removing your old braked fluid and replacing it with a fresh batch.

Regularly changing the clutch’s hydraulic fluid is an important aspect of car maintenance and is done for the same reasons you change brake fluid– contamination. Contamination is in the form of air bubbles and water vapor, which cause problems when activating the clutch.

Over time, hydraulic fluid breaks down as the clutch wears down, introducing leaks into the hydraulic system, which means it’s time to replace it with hydraulic fluid.

When replacing the hydraulic fluid in the clutch master cylinder, you introduce air bubbles into the hydraulic system. You must do a thorough job of removing ai; otherwise, you’ll have to contend with a non-existent or soft action when you depress the clutch.

Regularly replenishing your Honda Civic hydraulic fluid comes with a lot of benefits. It helps give you a smoother clutch action, a seamless gear-changing experience, and an improved clutch control biting point.

Conversely, failing to replenish your clutch fluid regularly will ultimately lead to the contamination of the hydraulic fluid and the wearing out of the one-way seal, all of which could lead to a non-functional clutch.

That being said, bleeding a Honda Civic master cylinder involves handling corrosive liquids and using specialized techniques that could potentially damage your clutch if performed incorrectly.

Bleeding Honda Civics’ clutch master cylinder

It’s worth noting that bleeding a Honda Civic’s master cylinder is no different to bleeding any other car; without further ado, here’s how to bleed the clutch master cylinder in your Honda Civic.

Phase One: Preparation

You’ll need to get some protective goggles or any other form of protection to protect your eyes from the aerosols and brake fluid splashes, an eye irritant. We recommend not using your conventional safety glasses since you’ll be working under your car, and the best way to protect your eyes is with the goggle type of safety glasses.

Additionally, you might want to get a pair of latex gloves to protect your skin since it’s also irritating. You also want to have your buddy standing by to fully depress the clutch pedal, keep it steady and release the clutch on your say.

We’ll be working under the car, so you’ll need to get your jack to support your car while you’re bleeding the clutch. Since we’re bleeding a Honda Civic, you’ll need an 8-millimeter ring spanner.

If this is your first time, you want to get about 500ml of brake fluid to be safe but more experienced drivers can use about 250ml. Speaking of brake fluid, you also need a container to hold the brake fluid. As you’re bleeding the master cylinder, drill a hole through the lid.

People typically use an empty mason jar or soda bottle—which we will use in our guide. Whichever you decide on, you want to get a clear hose wide enough to fit on the bleeder valve and the container’s opening so you can see when the air or contaminated fluid has been bled off.

Things tend to get messy, especially if you’re a beginner, so having some rugs handy can go a long way in cleaning up any brake fluid spills. Remember, it’s corrosive to you and your car paint so be careful.

Phase Two: Procedure

1. Start by checking your master cylinder’s reservoir brake fluid levels—it should be at the top of the line, if not, fill it up and close the cap. Don’t worry about overfilling it; we’ll be draining a generous amount of brake fluid, so it’s fine for now.
2. Jack up your car’s front and find the bleeder nipple on the slave cylinder, uncap it and store the cap somewhere safe. Its location varies from car to car, but it’s usually right next to your transmission—look for a nozzle sticking out of a bolt.
3. Attach your see-through hose to the nipple of your Honda Civic’s slave cylinder—make sure it’s securely attached, and use the 8mm ring spanner to crack it loose—you’ll only need to turn it the quarter way it to start bleeding and leave it open.
4. Ask your buddy to depress the clutch pedal and hold it steady fully. They mustn’t let go until you close the bleeder screw. Otherwise, you risk letting air into the system.
5. Ensure you’re in the right position to watch your Honda Civic’s clutch fluid bleed into your bottle or mason jar. Tighten the bleeder screw in the clockwise direction to seal it back up and prevent air from being sucked in before asking your friend to release the clutch fully.
6. Rinse and repeat while adding more brake fluid to the master cylinder’s reservoir with each bleeding cycle to ensure it doesn’t run out of brake fluid.

Ford Motor

Ford Motor has been a fan of mechanically actuated clutches for a long time, and you can find them in their earlier truck models. As great as they are in detecting changes in your clutch’s biting point, they must be adjusted regularly to keep the clutch working smoothly, thanks to their many components.

They felt this was too much of a hassle and decided to switch to the easier-to-install, self-adjusting, and small-sized hydraulic clutches. Hydraulic-actuated clutch systems offer drivers extended reliability and reduce the number of trips to the garage for adjustments.

Ford Motor is known for its dreaded concentric clutch slave cylinder, and the uncertainties and difficulties that come with them are all too familiar to an experienced mechanic. And it seems GM is following suit with some of their CSCs as if to add salt to injury.

Some GM cars come without bleeding ports, and most of their designs require you to remove the transmission to access the slave cylinder. To help the mechanically inclined drivers bleed their Ford f150’s clutch, we outlined a few steps to get the job done.

How to bleed hydraulic clutch ford f150

If you’ve recently changed your Ford f150’s master or slave cylinder, then there is a chance you’ve introduced air into your hydraulic linkage clutch. Air entering the hydraulic system forms compressible air bubbles that dull the hydraulic pressure transmitted when the clutch is depressed.

By dulling the transmitted hydraulic pressure, the air bubbles limit the travel of your slave cylinder’s pushrod, so it can’t properly engage the clutch fork to disengage the clutch disk from your engine’s flywheel. Bleeding the clutch is a great way of ensuring you’re running a well-oiled machine.

Bleeding a Ford f150 hydraulic clutch

Bleeding a Ford f150 hydraulic clutch can be as easy as bleeding the brake system if you know what you’re doing, but first, here are some safety precautions.

Step One: Safety First

Clutch fluid, aka brake fluid, is very corrosive on your vehicle’s paint and irritates the skin and the eyes. You mustn’t handle brake fluid with your bare hands and wear personal protective equipment while handling it.

These include safety glasses—goggle style, your traditional safety glasses won’t do. Additionally, you want to get latex or neoprene gloves to protect your skin from the hydraulic fluid and a rug to help clean up any spilled brake fluid while bleeding your f150.

Step Two: Tools and Supplies

Since we’re bleeding the clutch, you’ll need the brake fluid to top it up. If you’re not sure about the correct brake fluid—though it’s typically D.O.T 3, check your car’s manual and you can sometimes find it written right next to your master cylinder’s reservoir in the engine bay.

You’ll also need to get a jack and two jack stands. Even though Ford Motor is known for its high trucks, some, like the Ranger, don’t give you enough room for bleeding and require you to jack it up.

As we mentioned, brake fluid is corrosive, so you’ll need to get a container to hold it as you bleed your f150’s clutch. We prefer you use a bucket, but feel free to use whatever works for you, and you’ll also need about 6 inches of tubing—preferably rubber.

Lastly, you’ll need a box-end wrench to unwind the bleeder nipple and an engine cleaner. We recommend having someone help you bleed your Ford f150’s hydraulic clutch.

Step Three: Disconnect and Jack the front

When performing any automotive repair, it’s recommended that you remove the negative cable from the battery, and it’s the first thing we’ll do before jacking the car up.

Position the two jack stands under the “A” arm behind the front wheels when jacking the car’s front up, and make sure it’s well-supported before removing the jack.

Step Four: The master cylinder

Find your master cylinder’s reservoir—usually on the driver’s side next to the firewall, uncap it and, using a rug, wipe off the debris and dirt on the cap and the master cylinder. If it’s too dirty, that’s where the engine cleaner comes in.

Step Five: The slave cylinder

Find the slave cylinder of your Ford f15; it’s typically found on the driver’s side right next to the transmission. Connect your 6-inch rubber tubing to the bleeder nipple and direct it to your empty container, the bucket which will collect the hydraulic fluid.

Using the box-end wrench, loosen the bleeder screw by turning it counterclockwise until you notice hydraulic fluid dripping into the bucket through the tubing. When you notice a continuous stream of brake fluid without any air bubbles, it’s time to close the bleeder.

Step Six: back to the master cylinder

With your D.O.T. 3 brake fluid, fill up the f150’s master cylinder to the top line while leaving the diaphragm and cap off. Ask your friend to get in the driver’s seat and ask them to depress the clutch pedal to its maximum pedal travel, and then quickly release it.

Ask them to repeat this cycle, i.e., fully depressing the clutch pedal and instantly releasing it, ten times. this process was developed to force any remaining air bubble in the hydraulic system down to your clutch’s slave cylinder.

That said, be sure to top up the brake fluid, so the master cylinder doesn’t run out of hydraulic fluid. Now ask your helper to fully depress the clutch pedal and hold it steady until you say otherwise—it’s important they follow your instruction to a tee, or you risk letting air in.

Step Seven: the slave cylinder

Now loosen the bleeder screw and leave it open until there’s a steady stream of brake fluid and no more air bubbles are in the system. You can now tighten the bleeder screw up but make sure not to overtighten it, and then remove the 6-inch rubber tube and the bucket.

Step Eight: Release and refill

Ask your impatiently waiting friend to fully release the clutch once the bleeder screw on the slave cylinder has been shut off. Fill up your master cylinder’s reservoir with brake fluid to its fill line, add the diaphragm and close the cap.

Step Nine: Jack it down and reconnect

You’re done bleeding the clutch of your Ford f15; it’s time to jack up the front and remove the two jack stands before lowering the car back to the ground. Reconnect the cable back to your battery, start the engine and look for leaks.

Conclusion

You must regularly change your clutch fluid every few years because, over time, it wears down, gets contaminated, and degrades your master cylinder. Bleeding your clutch can make a world of difference in the feel of your clutch, the biting point, and gear control.

FAQ

How much does it take to bleed the clutch?

Allowing gravity to bleed the slave cylinder clutch is relatively straightforward and should not take more than 5 minutes. Most mechanics worldwide charge between $60 and 70 for the hydraulic system, while the labor costs set you back to $40 to $60. You may pay for parts at an average cost of around $20.

What happens when your car runs out of clutch fluid?

When you run out of clutch fluid then, you are going to have challenges shifting gears. You will also notice that the clutch does not release properly. Sometimes the gear change challenges are accompanied by a grinding sound.