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Brake Booster Vacuum Pump Replacement
 
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Pelican Technical Article:

Brake Booster Vacuum Pump Replacement

Jared Fenton

Time:

1 hour1 hr

Tab:

$250

Talent:

**

Tools:

Two 10mm wrenches

Applicable Models:

Volvo C30 T5 (2008-13)
Volvo C30 T5 R-Design (2008-13)

Parts Required:

Brake booster vacuum pump

Hot Tip:

Check the orientation of the rubber grommets when installing the new pump

Performance Gain:

Better braking

Complementary Modification:

Change brake pads

The brake booster is a device that uses vacuum pressure from the engine to decrease the amount of effort needed to push down the brake pedal. It does this by using a large vacuum diaphragm controlled by a small electric air pump. The vacuum source is the engine vacuum itself, connected to the intake manifold with a check valve to keep the engine from stalling or surging. On the Volvo C30, there is also a secondary vacuum source from a small electric pump mounted in front of the battery.

A failing brake booster system will result in a brake pedal that takes more effort to push and also to slow the vehicle. Typically, if there is a problem with the system, the vehicle will trigger a fault code indicating a problem. If there is a problem with the vacuum signal, you'll likely notice that the brake pedal slowly sinks to the floor when the engine is running and you are stopped. Usually, this is accompanied with a hissing noise as there will be a leak in the system, either at the brake booster diaphragm or the air line to the vacuum pump. If there is no hissing and the pedal still goes down, you should use a scanner to check for fault codes and determine if it is the vacuum pump.

If the pedal does go down with the engine off, it's an indication that there are problems with the hydraulic portion of the braking system. Most automotive braking systems work by using a hydraulic master cylinder to pump brake fluid to each brake caliper on the vehicle. The entire hydraulic circuit is essentially a force amplifier that along with the brake booster takes little relative effort to press the pedal and stop the car.

The first thing to always check is the brake fluid level. If the fluid level is low, check for leaking brake fluid under the car and also at each brake caliper. If the fluid level is fine, try bleeding the system. A soft pedal can be caused by air in the brake lines. See our article on Bleeding Brakes for more information. If the brake lines have been bled and there is no obvious change in the brake fluid level, it is probably a good bet that the check valve in the master cylinder has failed and it is time to replace it.

Shown here is the vacuum pump that operates the brake booster.
Figure 1

Shown here is the vacuum pump that operates the brake booster. Begin replacement by pressing up on the release tab (green arrow) for the vacuum hose connection and pull the line off the pump.

The pump is secured to the mounting bracket with two 10mm bolts (green arrows) and two 10mm nuts below (yellow arrows).
Figure 2

The pump is secured to the mounting bracket with two 10mm bolts (green arrows) and two 10mm nuts below (yellow arrows). Take note of the orientation of the rubber grommets above and below the pump. You'll need to loosen the bolts while counter holding the nuts. Be careful not to drop the nuts or lower grommets into the engine bay. Once loose, move the pump upward.

Move the pump out of the way to access the electrical connector.
Figure 3

Move the pump out of the way to access the electrical connector. Slide the connector towards the front of the car to release it from the securing tab. Now press the locking tab (green arrow) and pull the connector apart.

Shown here is the orientation of the grommets with the pump removed.
Figure 4

Shown here is the orientation of the grommets with the pump removed. Note that the middle grommet (green arrow) is indexed to fit inside the ears of the pump. The middle grommet fits on top of the mounting bracket while the lower grommet (yellow arrow) fits below the bracket.

Here is a clearer detail of how the indexed grommets (green arrows) fit into the ears of the pump.
Figure 5

Here is a clearer detail of how the indexed grommets (green arrows) fit into the ears of the pump. Installation is the reverse of removal.

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