MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
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In this guide (5 sections)
Step-by-step instructions on how to replace the rear brake pads and rotors on any Mercedes-Benz ML320, ML430, ML350, ML500 and ML55, years 1998 to 2005
If this is your first time doing this job, plan on spending around 4 hours. Make sure you have all your tools and parts ready. We strongly recommend installing ceramic brake pads and new rotors. Use quality brake pads that match the vehicle VIN and brake package. Ceramic pads can reduce dust and noise, but braking characteristics vary by manufacturer and pad compound. You can get ceramic pads for almost the same price as semi-metallic ones. You can get new rotors and ceramic brake pads for under $100.
Applicable Models
Models: ML320, ML430, ML500, ML350, ML55
Years: 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
Parts Needed
Notes Before You Start
- Ensure no mineral oil, grease, or other substances enter the brake system.
- If the vehicle has been in a severe impact, Mercedes calls for replacement when the hydraulic unit itself has received a heavy blow or shows evidence such as damaged lines, leaking connections, damaged wiring, visible block damage, or displacement from its bracket
- Avoid using hammers. Do not remove the brake caliper with a hammer, pliers, levers, or similar tools.
- When removing or installing the wheel, be careful not to bend the dust shield on the back of the rotor. If you bend it, you will hear a scratching noise when you put everything back together and start driving. If you bend the dust shield on the back of the rotor, you will need to remove the wheel and bend the shield away so it doesn’t touch the rotors.
- Work on level, stable ground and chock the FRONT wheels before you lift the rear. On this vehicle the parking brake works through the rear brakes you are about to take apart, and step 1 has you release it, so it cannot hold the car for you. Raise at the lifting points Mercedes-Benz designates for the W163 and lower the vehicle onto appropriately rated jack stands. Never work under a car held up by the jack alone.
- If you were driving the car before working on it, be careful, as the rotors will be hot.
- Do not disconnect the brake hose for this repair. Support the caliper so the hose is not stretched. If a brake hose is opened, bleed the brake system and check carefully for leaks before driving.
Step by Step Instructions
- Loosen your lug nuts; do not remove them yet.
- Jack up the car. Make sure to secure it with jack stands.
- Release the parking brake. Since you will be removing the rotors, you must ensure the parking brakes are loose. Otherwise, you cannot remove the rotors without damaging the brake shoes. If you need to replace the rear brake shoes as well, check out remove and install emergency brake shoes M-Class W163
- Remove the brake fluid reservoir cap.
- Remove the bolts on the rear of the brake caliper.
- Remove the brake caliper. Make sure you secure the caliper. Don’t let it hang or put pressure on the hydraulic brake hose.
- Remove the support plate.
- Remove the security bolt. Mercedes specifically says to back off the parking brake adjustment mechanism if the drum has worn in; otherwise, the parking brake shoes can be damaged.
- Remove the rear rotor. Make sure you have your parking/emergency brakes released.
- Install new rotor. Clean the surface where the rotors sit. Clean the hub and rotor contact surfaces. Apply only a light film of suitable grease to the rotor centering seat. Keep grease off the rotor friction surfaces and wheel bolt seats.
- Install the locking bolt and tighten it to 23 Nm.
- Install new brake pads on the calipers. First, you must install the inner brake pad into the piston. Then install the outer brake pad. Make sure to clean the surfaces where the brake pads slide. You will need to press the cylinder in the caliper. You will need a caliper press for this. Fixed W163 calipers use retaining pins and a retaining spring, with the pads pulled from the fixed caliper. Ensure you install a new brake wear sensor if your old one is worn out.
- Install the caliper. Two different torque figures apply here depending on which caliper your vehicle has, so confirm yours before you pull the wrench. The two bolts at the back of the caliper are 23 Nm, while Mercedes-Benz specifies 115 Nm for the rear fixed caliper to wheel carrier bolts. Those are not alternatives for the same fastener and the difference is five to one, so check your own caliper design against a Mercedes-Benz source rather than guessing from the photographs. Mercedes-Benz also calls for the self-locking fixed caliper bolts to be REPLACED rather than reused, so order them with the pads if your car has that type.
- Reinstall the rest in reverse order. W163 wheel bolts are specified at 150 Nm.
- Remember to put the cap back on the brake fluid reservoir.
- Start the car but do not drive yet. Before driving, press the brake pedal several times until it feels firm. Check the brake fluid level and correct it if necessary. Confirm normal brake operation before returning the vehicle to the road. For the first few miles, treat the brakes gently and follow the bed-in procedure supplied with your pads: new pads and new rotors need a controlled set of stops to transfer an even layer of friction material, and hard stops before that happens are what leaves you with a judder you then blame on the rotors.
Video: Rear Brake Pads on the W163 ML320, 1998 to 2005
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
