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Pelican Technical Article:

Clutch Bleeding

Nick Czerula

Time:

1 hour1 hr

Tab:

$30

Talent:

**

Tools:

7mm wrench, pressure bleeder, 8mm nut driver

Applicable Models:

BMW 525i/xi Sedan (2004-07)
BMW 528i xDrive Sedan (2009-10)
BMW 528i/xi Sedan (2008-10)
BMW 530i/xi Sedan (2004-07)
BMW 530xi Wagon (2006-07)
BMW 535i xDrive Sedan/Wagon (2009-10)
BMW 535i/xi Sedan (2008-10)
BMW 535xi Wagon (2008)
BMW 545i Sedan (2004-05)
BMW 550i Sedan (2006-10)

Parts Required:

Brake fluid and brake cleaner

Hot Tip:

Bleed vehicle twice to ensure all air is removed from system

Performance Gain:

Good clutch operation

Complementary Modification:

Replace clutch master and slave cylinder

When you step on your clutch pedal you are compressing a piston in your clutch master cylinder. This cylinder is full of brake fluid. The brake fluid that is now under pressure travels through your clutch line and is finally applied to your slave cylinder. The slave cylinder pushes on a fork that depresses the clutch pressure plate, allowing you to disengage the clutch. If you have opened up the system to service it or you just want to flush out the old brake fluid you should bleed your clutch. When the system is open air gets in. The bleeding process bleeds the air out of the system. If you add new fluid to the master cylinder reservoir as you bleed the brakes the old fluid is forced out and the new fluid is drawn in. BMW recommends you flush out your hydraulic clutch system every two years.

Remember, your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below.

There are a few ways to bleed your clutch. There are pressure bleeders available that apply pressurized brake fluid to the master cylinder reservoir. All you have to do is open the bleeder valve. The new fluid from the pressure bleeder tool is forced into the clutch master cylinder with air pressure. The old fluid is forced out the bleeder screw. Simply open the bleeder until you see cleaner brake fluid come out and then close the bleeder screw. The maximum pressure you want to run through the hydraulic clutch system using a pressure bleeder is 10 PSI. This is the procedure we are describing in this tech article. If you have the aforementioned tools follow the tool manufacturer's instructions that came with the tool.

There are vacuum bleeders that work on the vacuum principle. There are two types. One is an air powered one that uses shop air pressure to generate a vacuum in the tool. This vacuum source is piped to the bleeder screw. With vacuum applied, open the bleeder screw and vacuum will suck out the old fluid until the new fluid from the reservoir comes out. Then close the bleeder screw. There are manual tools that have you manually pump the tool to generate the vacuum. You will have to close the bleeder screw from time to time and pump on the tool to make vacuum. Then open the bleeder screw again.

The final method does not require any tools but you will need a helper. Make sure to clean around the cap before removing it, as you do not want to get any dirt into the reservoir. Fill the reservoir with new brake fluid. It is very important that you keep the reservoir full during the brake bleeding procedure. If it runs dry you will allow air to get drawn into the system through the master cylinder and you will have to start all over again. Check the brake fluid level frequently. Remove the slave cylinder from the transmission. Hold the rod firmly against the transmission. You will be holding the rod steady so you can allow it to extend as you bleed it. Have your helper step on the clutch pedal very slowly. Let the slave cylinder push you away from the transmission, but do not allow it to lose contact with the transmission housing. Open the 7mm bleeder, compress the rod, close the bleeder and repeat this step until the air is out of the system. Then reinstall the slave cylinder. Repeat the bleeding process, this time with the slave cylinder installed. Properly tighten the bleeder screw. Don't spill any brake fluid on the vehicle, if you clean it immediately with soapy water. Use brake cleaner in a well-ventilated area and let the components air-dry. The brake cleaner will evaporate with time. Make sure the brake fluid reservoir is full and install the cap.

The procedure below will review the manual bleeding method.

Raise and support the vehicle on jack stands. See our tech article on jacking up your vehicle.

The clutch master cylinder (red arrow) has a short piston throw.
Figure 1

The clutch master cylinder (red arrow) has a short piston throw. This is why it is important to work slowly and assist the slave cylinder in the bleeding process. Start with the manual bleeding process described above. Remove the slave cylinder from the transmission. Hold the rod firmly against the transmission, you will be holding the rod steady so you can allow it to extend as you bleed it. Have your helper step on the clutch pedal very slowly. Let the slave cylinder push you away from the transmission, but do not allow it to lose contact with the transmission housing. Open the 7mm bleeder, compress the rod, close the bleeder and repeat this step until the air is out of the system. Then reinstall the slave cylinder.

Remove the cabin microfilter and microfilter housing (red arrow).
Figure 2

Remove the cabin microfilter and microfilter housing (red arrow). See our tech article on engine covers removing.

Make sure to clean around the cap before removing it, as you do not want to get any dirt into the reservoir.
Figure 3

Make sure to clean around the cap before removing it, as you do not want to get any dirt into the reservoir. Fill the reservoir with new brake fluid. It is very important that you keep the reservoir full during the brake bleeding procedure. If it runs dry you will allow air to get drawn into the system through the master cylinder and you will have to start all over again. Follow the instruction that came with your bleeder.

Then install the pressure bleeder adapter to the brake master cylinder.
Figure 4

Then install the pressure bleeder adapter to the brake master cylinder. Pressurize the brake system to a maximum of 10 psi.

Remove the transmission splash shield.
Figure 5

Remove the transmission splash shield. See our tech article on engine splash shield and reinforcement plate removing. Working at the slave cylinder, remove the rubber cover (red arrow), if it hasn't been already.

Open the bleeder screw.
Figure 6

Open the bleeder screw. Allow the fluid to run out into a drain pan until no air bubbles are present and clean fluid is being expelled. Once the fluid is air-free, close the bleeder and check the operation of the clutch pedal. If the pedal is soft or the clutch does not disengage, try bleeding it again. If needed, remove the slave cylinder again to assist the piston during the bleeding process as described earlier.

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Page last updated: Fri 12/9/2016 02:43:32 AM