WM 300101 Checking Clutch Booster Circuit (Turbo Coupe, Turbo S Coupe, Turbo CABRIO, Turbo S CABRIO): Information

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2013 Porsche 911, 2012 Porsche 911, 2011 Porsche 911, 2010 Porsche 911, and 2009 Porsche 911. However, it is still accessible from the selected car via links, so may be relevant.

Clutch actuation, for the 911 Turbo, is assisted by a hydraulic auxiliary force (clutch booster circuit). This hydraulic auxiliary force acts on the clutch slave cylinder when de-clutching. A tandem pump -1- is used instead of the hydraulic single pump for power steering (997 naturally aspirated engine) in order to generate the auxiliary force.

This tandem pump (for clutch booster circuit and power steering) -1- has a combined supply tank/reservoir -4-

Tandem pump (assembly -2 and 3- )
Hydraulic pump for steering
Hydraulic pump for clutch booster circuit
Supply tank/reservoir (Pentosin reservoir in engine compartment)

Fig 1: Identifying Hydraulic Pump Components (Tandem Pump)

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

A pressure control valve and a pressure retaining valve are integrated into the combined supply tank/reservoir for the clutch booster circuit. These valves are located in the upper part of the tank .

Fig 2: Identifying Reservoir (Pentosin Reservoir In Engine Compartment)

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

A pressure accumulator -arrow- is screwed into the clutch slave cylinder. If the engine is switched off (with the system intact), the pressure accumulator -arrow- allows up to 20 (sometimes 25) clutch pedal actuations until an increase in pedal pressure is clearly felt. The booster circuit is then depressurized (pressure accumulator is empty).

Fig 3: Locating Pressure Accumulator

Courtesy of PORSCHE CARS NORTH AMERICA, INC.