Mercedes-Benz Parts Catalog Mercedes-Benz Accessories Catalog Mercedes-Benz Technical Articles Mercedes-Benz Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
Bookmark and Share

Pelican Technical Article:

Brake Booster Replacement

Time:

2 hours2 hrs

Tab:

$400

Talent:

**

Tools:

Socket set, flare nut wrenches, power bleeder

Applicable Models:

Mercedes-Benz W210 (1996-03)

Parts Required:

new brake booster

Hot Tip:

use paper towels and plastic bags to contain any fluid leaks from master cylinder lines

Performance Gain:

better braking

Complementary Modification:

replace master cylinder

Power brakes work by using vacuum from the engine to pull against a large diaphragm behind the master cylinder. This amplifies the force exerted on the brakes when you press the pedal down. After years of use, the rubber diaphragm inside the booster may leak or fail, causing the system to not work correctly. It usually results in having to push the pedal down harder when braking. In addition, a failing brake booster will create a vacuum leak which can affect the operation of the car's fuel injection system.

Before you replace your brake booster though, be sure that you check the vacuum hose connections that run to the engine to see if there are any leaks there The vacuum is routed from the engine via a long plastic hose that runs from the side of the intake manifold, up along the side of the engine compartment and eventually to the brake booster. Often times, the vacuum check valve at the end of the vacuum hose goes bad, causing the problems. An easy way to check the operation is to remove the vacuum line, and blow through both ends of the hose. If you can blow though both ends of the hose, the check valve is shot and must be replaced. If you can blow through one side of the hose and not the other, the check valve is operating and the booster must be replaced.

The first step in removing the booster is to remove the master cylinder (see Pelican Technical Article: Master Cylinder Replacement). With the master cylinder removed, you will need to remove the panel under the steering wheel to reach the nuts that hold the booster in place. Begin by removing the metal Phillips screws that hold the panel up underneath. Look up underneath the red hood release handle. You'll see small Phillips head screw. Remove the screw. Once these are removed, locate the plastic Phillips screw holding the footwell vent to the center console.

Once removed, rotate the vent clockwise 90 degrees to remove it. At the very bottom of the steering column, you will see a plastic nut. Remove the nut in order to release the lower under panel and lower it down slightly. You'll now have to route the hood release handle out through the back of the under panel. Once free, slide the locking connector on the OBD-2 port to the right to release it. Now take the under panel out of the car.

Once the under panel is removed, you will be able to access both the mounting nuts and also the pin that secures the brake booster to the brake pedal. The first thing to remove is the metal pin that secures the brake booster actuator. Unfortunately, the pin itself is really difficult to remove in place. You'll need to lift one edge of the pin up while you pull it out of the hole on the retaining shaft. I've included a picture of the pin and also the booster fork removed from the car to get a better idea of how the whole assembly goes together. Once the pin is removed, you'll need to push the axle out of both the brake pedal arm and the booster fork. Now use a 13mm socket on a long extension to remove the two nuts holding the booster to the firewall.

From inside the engine compartment, carefully pull the old booster out of the firewall. The new booster should have a new sealing gasket on the backside that will seal up against the firewall.

Once the master cylinder has been removed from the car, you'll begin to remove the brake booster by first prying out the vacuum line at the bottom of the booster (green arrow).
Figure 1

Once the master cylinder has been removed from the car, you'll begin to remove the brake booster by first prying out the vacuum line at the bottom of the booster (green arrow).

You'll need to remove the panel under the steering wheel in order to remove the brake booster mounting nuts.
Figure 2

You'll need to remove the panel under the steering wheel in order to remove the brake booster mounting nuts. Begin by first rotating the plastic screw shown here (green arrow) 90 degrees to unlock it, then pull the vent cover away. Also remove the Phillips head screw shown here (purple arrow).

Remove the screw holding the hood release handle to the underpanel (green arrow) as well as the Phillips head screw holding the left side of the underpanel in place (purple arrow).
Figure 3

Remove the screw holding the hood release handle to the under panel (green arrow) as well as the Phillips head screw holding the left side of the under panel in place (purple arrow).

Unscrew the plastic nut holding the back of the underpanel to the chassis (green arrow).
Figure 4

Unscrew the plastic nut holding the back of the under panel to the chassis (green arrow).

Now lower the underpanel and carefully remove the hood release handle from the backside of the panel.
Figure 5

Now lower the under panel and carefully remove the hood release handle from the backside of the panel.

Release the OBD-2 diagnostic port from the backside of the panel by sliding the locking latch to the right as shown here (green arrow).
Figure 6

Release the OBD-2 diagnostic port from the backside of the panel by sliding the locking latch to the right as shown here (green arrow).

With the panel removed, you can now access the nuts that hold the booster in place.
Figure 7

With the panel removed, you can now access the nuts that hold the booster in place. In this picture, you can see the two 13mm nuts that hold the booster to the firewall of the car (green arrows). Remove these nuts and also the retaining pin (purple arrow) that secures the booster to the firewall. Once removed, slide the retaining axle out of the booster arm in the direction of the yellow arrow.

ThisPicture shows the retaining pin a bit more clearly and removed from the car.
Figure 8

This picture shows the retaining pin a bit more clearly and removed from the car. It's difficult to show how to remove this when it is installed in place. Pry up at the bottom of the pin to clear the edge of the axle (green arrow) while pulling up in the direction of the yellow arrow. Once the pin is removed, slide the whole axle assembly in the direction of the purple arrow.

Shown here is the brake booster removed from the car.
Figure 9

Shown here is the brake booster removed from the car. It's important to use a new sealing gasket (green arrow) when installing the new booster.

It's a good idea to vacuum up any leaves or dirt that may be under the brake booster.
Figure 10

It's a good idea to vacuum up any leaves or dirt that may be under the brake booster. In our case, there was, what appeared to be, a rat's nest tucked up under the vents (green arrow).

Bookmark and Share
Comments and Suggestions:
ron Comments: 80 450sel have installed new brake booster still do not have a power brake feel. have to push peddle very hard on stops impossible to slide tires or rapid stop. no abs light on....
October 27, 2013
  Followup from the Pelican Staff: Do you have vacuum going to your booster. While the engine is running remove the vacuum line and see if it sucks your finger into the opening - Kerry at Pelican Parts  
Mike v Comments: Gas pedal goes down cant give gas but engine stays running
March 16, 2013
  Followup from the Pelican Staff: Sorry, insufficient data and unrelated to brake systems.
roy@pelicanparts.com
 
Mike Comments: 03 c240 Benz ESP bas comes on break pedal wont work but car engin stays running will pull over turn engin off start back up so the gas pedal can work
March 16, 2013
  Followup from the Pelican Staff: This is a critical safety issue.
Take it to your local MB dealer for diagnosis and repair.
roy@pelicanparts.com
 

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Sat 12/3/2016 02:13:05 AM