Reservoir Filler Plug BMW E60 M5 E63 M6 SMG III

The pressure accumulator is responsible to store the pressure of the hydraulic system for later access by the actuators. This piston type accumulator has two cells: one cell storing the hydraulic fluid and one cell containing a Nitrogen gas filling which creates the counterpressure. Both cells are separated by a moving piston. Typical symptoms of a faulty pressure accumulator are frequent and short pump cycles. If there is no more preload pressure left in the accumulator, the pump runs every few seconds, which ultimately leads to a consequential damage of the pump motor. Along with the pump motor, a faulty pressure accumulator is one of the most common causes of pressure build-up issues and is one of the few wear parts in the system that should be regularly checked and replaced if necessary.

The replacement part we offer is a brand-new OE upgrade with improved internal piston seals, resulting in significantly increased durability.

The pressure sensor measures the hydraulic pressure in the accumulator. Based on this value, the SMG enables and disables the hydraulic pump to fill up pressure. This is a brand-new original part.

The internal gears of the hydraulic pump tend to wear mechanically and as a result the pump can no longer build up pressure. Our set includes new gears and metal seals that exactly match the original specifications and restore the function of the pump. In the process of overhauling the gear pump, we also recommend replacing the seals, which you can find here.