Vacuum pump for brake servo. Porsche 987/981 Boxster / 987C/981C Cayman / 997 / 991

This vacuum pump is a component in the brake servo (brake booster) system in various Porsche models (Boxster/Cayman, 997, 991, etc.). It helps generate the vacuum needed by the brake booster so that the driver has power assistance when applying the brakes.

In many modern Porsche engines (especially at higher performance levels, forced induction, or in engines where manifold vacuum is insufficient under certain operating conditions), an auxiliary vacuum pump is used because the engine’s intake manifold vacuum alone may not always provide adequate or stable vacuum for the brake booster.

The pump is typically driven mechanically (via the engine belt, accessory drive, or via an electric drive depending on vehicle) and draws vacuum from a chamber, then supplies that vacuum to the brake booster. Because the brake booster relies on consistent vacuum, degradation or failure of this pump can lead to harder brake pedal efforts or weak assistance under certain conditions.

Loss of vacuum / reduced vacuum output As the pump wears, internal leaks (seals, vanes, diaphragms) reduce its ability to maintain the required vacuum level. This causes the brake servo to get less assist, making the pedal feel harder.

• Porsche Boxster 987 MKII 2.9L 2009-2012
• Porsche Boxster S 987 MKII 3.4L 2009-2012
• Porsche Boxster 981 2.7L 2012-16
• Porsche Boxster 981 S / GTS 3.4L 2012-16
• Porsche 997 MKII Carrera C2 3.6L 2009-12
• Porsche 997 MKII Carrera C4 3.6L 2009-12
• Porsche 997 MKII Carrera C2S 3.8L 2009-12
• Porsche 997 MKII Carrera C4S 3.8L 2009-12
• Porsche 997 MKII Turbo 2010-13
• Porsche 997 MKII GT2 RS 2011-13
• Porsche 991.1 Carrera C2 3.4L (350Bhp) 2012-16
• Porsche 991.1 Carrera C2S 3.8L (400Bhp) 2012-16
• Porsche 991.1 Carrera C4 3.4L (350Bhp) 2012-16
• Porsche 991.1 Carrera C4S 3.8L (400Bhp) 2012-16
• Porsche 991.1 Turbo 3.8L (520bhp) 2014-16
• Porsche Cayman 2.9L 987C MKII 2009-12
• Porsche Cayman S / R 3.4L 987C MKII 2009-12
• Porsche Cayman 2.7L 981 2013-16
• Porsche Cayman S / GTS 3.4L 981 2013-16

Diagram ref no 10

This pump generates the vacuum required by the brake booster (servo), allowing the system to amplify pedal force for smooth, consistent braking. By maintaining the correct vacuum pressure under varying engine loads, it ensures stable braking response and driver confidence.

Why replacement matters:

• Intermittent vacuum supply. Pump may fail or fluctuate in output under certain engine speeds or loads, leading to inconsistent pedal feel.
• Mechanical wear / bearing failure. The internal rotating components, bearings, or drive shaft can wear, leading to noise, inefficiency, or eventual seizure.
• Leaks (external or internal). Seal failure can cause air leaks (vacuum loss) or allow unmetered air into the system, reducing servo effectiveness.
• Cracks, housing damage or corrosion. Over time, housing cracks or corrosion can affect integrity and result in leaks or mechanical failure.
• Failure of check valves / one-way valves. Some pump assemblies include check valves to maintain vacuum or prevent backflow; if these fail, vacuum can be lost.
• Age / fatigue. After many years and many duty cycles, material fatigue and seal degradation can degrade performance even without catastrophic failure.
• Associated component failure. Blocked vacuum lines, failed hoses, or clogged filters can mimic pump failure; sometimes the pump is replaced during diagnosis or when other parts are replaced.