For the Bentley Continental GTC (2006–2018), the part number 3W7871789 refers to the core hydraulic pump assembly for the convertible roof system. This unit is the “heart” of the convertible top, providing the high-pressure fluid required to actuate the various cylinders that lift the roof and the tonneau cover.

1. Technical Specifications

The 3W7 prefix indicates this is a GTC-specific part, distinct from the coupe models.

• Manufacturer: Typically manufactured by Hoerbiger for Bentley.

• Function: Powers the hydraulic rams that move the main roof bow, the tensioning bow, and the rear “deck” (tonneau) lid.

• Integration: The assembly includes the electric motor, the hydraulic fluid reservoir, and the solenoid valve block that directs fluid to the correct cylinders.

• Fluid Type: Requires specialized Pentosin CHF 11S (or the Bentley-equivalent green hydraulic mineral oil). Using the wrong fluid can swell the seals and cause system-wide failure.

2. Common Symptoms of Failure

• The “Whine”: If you hear the motor spinning (a high-pitched whine) but the roof isn’t moving, you likely have low fluid levels or an internal seal leak in the pump.

• Stalling Mid-Cycle: If the roof stops halfway through opening, it often indicates the motor is overheating or the thermal sensor on the pump is failing.

• Hydraulic Leaks: Check the area around the pump (located in the trunk/boot area, typically behind the rear seats or under the floor) for clear or green oily residue.

3. Maintenance & Installation Tips

• Fluid Check: There is a “Min/Max” mark on the translucent plastic reservoir. If the fluid is low, you must find the leak before refilling, as the system is sealed and should not lose fluid under normal operation.

• Relay Replacement: Like the air suspension pump, it is highly recommended to replace the roof pump relay when installing a new unit. A sticking relay can cause the pump to run until it burns out.

• Bleeding the System: The Bentley roof system is generally “self-bleeding.” After installation and filling, cycling the roof 3–5 times manually or via the switch will usually purge any air pockets.