Seals inside the pump get upgraded, and design flaws get rectified. Pumps rebuilt by Top Hydraulics perform better than brand new ones, and Top Hydraulics' seals will far outlast those in brand new pumps. The pump we are shipping to you may not be perfect cosmetically, because it has been used before. We do our best to clean up or polish out external blemishes, but what really matters is what's inside the pump. We are certain that we are shipping a pump to you that is better inside than a brand new one, and we back that by a 3-year warranty.

The most common failure symptom on used BMW E93 hydro units is a gradual loss of pressure and power. There are various possible reasons for gradual power loss inside the pump/hydro units, ranging from degrading electric motors through pump pistons wearing out and check valves bypassing, to pressure regulators failing, or even hydraulic fluid seeping into the electric motor. Top Hydraulics will check that all these components meet or exceed factory specs and exchange or upgrade them if necessary. Bench testing includes all valve functions, pressure test, flow test, extended load test, and test for leaks, to make sure that factory specs are exceeded before the pump ships back. Beware when purchasing used pumps that those may actually be units that are still pumping, but are not able to complete the convertible top's opening or closing cycle without manual assistance.

Some of these pumps have external leaks (you may find the foam casing soaked in hydraulic fluid). The most common source for external leaks on these pumps are the port seals. Port seals are tiny seals of special shape that are sealing the hydraulic lines when they are plugged into the pump. The port seals are behind brass bushings. These bushings are pressed into the pump housing, and they are made to 1/100 mm precision. Any DIY repair attempt would destroy the bushings. Top Hydraulics replaces the original port seals with an improved version made of Viton, which has practically unlimited shelf life. Before assuming that the pump is leaking externally, check the hydraulic lines going into the pump to make sure they are dry.

If your top is moving slowly or erratically, make sure that all sensors in the system are working, and that there is good power supply and ground to the pump. If sensors in the top's system give the wrong signal, then the computer will stop your top's function as soon as it is deemed unsafe based on the readout from the sensors.