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Audi A4 Brake Booster Vacuum Pump Replacement
 
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Pelican Technical Article:

Audi A4 Brake Booster Vacuum Pump Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$425

Talent:

**

Tools:

Flathead screwdriver

Applicable Models:

Audi A4 (2002-05)
Audi A4 Cabriolet (2003-06)

Parts Required:

Brake Booster Vacuum Pump

Hot Tip:

Check for leaks in the hoses before replacing pump

Performance Gain:

Better braking

Complementary Modification:

Replace master cylinder

Without a doubt, your brakes are the most important system on the car.

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. The Audi A4 also uses a power brake vacuum pump to assist in and maintain vacuum pressure in the booster. The booster, pump and lines can fail which usually results in having to push the pedal down harder when braking. In addition, a failing brake booster, lines or pump can create a vacuum leak which can affect the operation of the car's fuel injection system.

The brake vacuum pump is very easy to change which is nice as it is very expensive. Before you change out the pump make sure to check all the vacuum lines attached to it and the boosters as a broken, ripped, torn or leaking line can replicate the same type of problems as a broken pump.

The brake booster vacuum pump is located in the front left side of the engine bay (red arrow).
Figure 1

The brake booster vacuum pump is located in the front left side of the engine bay (red arrow). There is a vacuum line attached to it that passes through the firewall and attaches to the brake booster (yellow arrow).

The pump (red arrow) sits in a bracket and has a single vacuum line (yellow arrow) and electrical connection (green arrow) attached to it.
Figure 2

The pump (red arrow) sits in a bracket and has a single vacuum line (yellow arrow) and electrical connection (green arrow) attached to it.

This photo illustrates where the vacuum hose passes through the firewall and attaches to the brake booster (red arrow).
Figure 3

This photo illustrates where the vacuum hose passes through the firewall and attaches to the brake booster (red arrow).

Begin by disconnecting the electrical connection (red arrow).
Figure 4

Begin by disconnecting the electrical connection (red arrow).

The pump sits in a bracket with a clip on each side.
Figure 5

The pump sits in a bracket with a clip on each side. Simply unclip the pump from the bracket using hand pressure (red arrow).

You can now pull the pump straight up and out of the bracket (red arrow).
Figure 6

You can now pull the pump straight up and out of the bracket (red arrow). Next remove the hose from the pump.

The hoses come from the factory with a special clamp (red arrow).
Figure 7

The hoses come from the factory with a special clamp (red arrow). If you take your time you may be able to loosen the clamp by prying it gently apart and then re-crimp it but I would order and new clamp when ordering the pump. This is also a good time to inspect all of the vacuum hoses and replace any suspect looking ones. Please see our article on fixing vacuum leaks for additional information.

Before you reinsert the new pump onto the lower mounting grommet (green arrow) make sure to check the area around the bracket for dirt, fluids and debris.
Figure 8

Before you reinsert the new pump onto the lower mounting grommet (green arrow) make sure to check the area around the bracket for dirt, fluids and debris. The ABS control unit (red arrow) and the power steering reservoir (yellow arrow) are right beside the pump. Installation is the reverse of removal.


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