Without a doubt, your brakes are the most important systems on the car. The heart of the brake system is the master cylinder, which controls the hydraulic pressure of the entire system. Unfortunately, over many years, the master cylinder and reservoir have a tendency to wear out and leak. The leakage can occur internally or externally, resulting in a weakened braking system. If you have any problems with your brakes, and you think that it's related to the master cylinder or reservoir, you should probably replace it.

Replacing the master cylinder on the Mercedes W203 is not it is difficult, it is just a tight fit, but it should take no more than three hours including bleeding the brakes. The first step is to disconnect the battery. Next remove the level sensor connector from the top of the reservoir.

You'll want to try and get as much brake fluid as you can out of the fluid reservoir on top of the master cylinder. Open the cap on the reservoir and remove the strainer. Using a fluid pump or turkey baster, get as much of the old fluid out as you can. This helps prevent excessive spilling of brake fluid inside the engine compartment. It's also helpful to stuff a bunch of old rags or paper towels under the master cylinder to absorb any spills.

Use a 12mm flared nut wrench and remove the two brake lines from the master cylinder. Make sure you use a flared nut wrench and make sure that it is seated correctly; you do not want to strip the nut. Also be prepared to catch the small amount of brake fluid that is going to come out.

You are going to have to remove the brake lines that connect to the ABS unit to get the master cylinder out. Disconnect the lines from the ABS unit, follow the lines where they pass through the sheet metal and remove them from the rubber grommets and set them aside.

There is a rocker plenum on the front of the master cylinder. Remove the crush washer that secures it to the rubber grommet. The crush washer will need to be replaced as it is a single use piece. Slide the rocker off the front of the cylinder and remove it from the car.

Disconnect the brake pressure sensors from the bottom of each cylinder.

Now locate the two 13mm nuts on either side of the master cylinder. These nuts hold the master cylinder in place. You'll probably need an extension with a universal joint in order to reach both nuts. Pull the master cylinder straight forward off the brake booster then tilt it slightly sideways and remove it from the car.

Use a T20 Torx driver and remove the screw securing the reservoir from the master cylinder.

You'll want to mount the master cylinder in a vise, and then pry the fluid reservoir out of the rubber grommets on the top. It should pop out with just a little force.

Always install new gaskets when replacing the reservoir.

Note: When you reinstall the master cylinder the lower nut is very difficult to access. Try placing a small amount of tape or a small piece of rubber glove between the nut and socket to help keep the nut in place. Just make sure the threads are clear.

When installing the master cylinder onto the brake booster take extreme care that the thrust rod

sits in the master cylinder, other wise you can damage it and/or your brakes will not work! Always replace the gasket between the cylinder and booster when ever you remove the cylinder.

Next, carefully position both of the brake lines into the new cylinder and thread in the brake line fittings. Be very careful when doing this as these are very easy to strip out. Go slowly and make sure they thread in easily by hand.

Now fill the master cylinder reservoir with new brake fluid and pump the pedal a few times to build up pressure. Do not pump the pedal without fluid in it. You could score and damage the inside of the cylinder bore, rendering it inoperable. You'll have to bleed all of the brake lines at each wheel to get all of the air out of the system. Please see our article on how to bleed your brakes.

DO NOT drive the car without completely bleeding the brakes!

Read the Full Article: https://www.pelicanparts.com/techarticles/Mercedes-W203/BRAKES-Brake_Master_Cylinder_and_Resevoir/BRAKES-Brake_Master_Cylinder_and_Resevoir.htm

Time: 3 hours
Tab: $200
Tools: 13mm socket, T20 Torx, flare nut wrenches, power bleeder
Parts Required: New master cylinder
Hot Tip: Use paper towels and plastic bags to contain any fluid leaks
Performance Gain: Better braking
Complementary Modification: Replace brake booster

Applicable Models:
Mercedes-Benz C230 (2006-07)
Mercedes-Benz C240 (2001-05)
Mercedes-Benz C280 (2006-07)
Mercedes-Benz C32 AMG (2002-04)
Mercedes-Benz C320 (2001-05)
Mercedes-Benz C350 (2006-07)

Hochgeladen am 01.01.2021   Problem melden   Dieses Video bei YouTube   Pelican Parts bei Youtube