Part number commonly printed on the pump: DAT1-112408

BMW part number:

54377309634 

54377309634 

54-37-7-309-634 

54 37 7 309 634

Top Hydraulics sends the pump back filled with fluid when shipping within the US.

Rebuild & upgrade service for your Z4 convertible top pump, also known as Motor Assembly or Hydro Unit.

Common failures of E89 Z4 top pumps are caused by water intrusion, or by stuck relays burning out the motor and overheating the pump or by internal seals and valves or the solenoids wearing out. Your pump will ship back exceeding all manufacturer's specs. This is a full rebuild where the pump gets torn apart to the component level, all seals get replaced and upgraded, every component checked for tolerance and function and replaced as necessary. This is a true rebuild by professionals, not some junk yard or garage outfit using a trial-and-error method where components get swapped until the pump seems to work, or only replacing the electric motor if that one was burnt out. At Top Hydraulics, we design our own seals designed to far outlast the original ones and allow for more back pressure in the reservoir. We also rewind our electric motors in house, using about 50% more copper than the original manufacturer. The latter is generating more power at less energy consumption, resulting in a motor that does not overheat easily any more. The E89 Z4 Hydro Units are very complex pumps with various weak spots that will eventually fail. Let Top hydraulics take care of it and send you a pump that is better inside than a new one from BMW...

The pumps shipping from Top Hydraulics may not look as pretty as brand new ones but we are sure that they are better inside and outlast new ones under similar circumstances. 

There may be a surcharge for missing parts or abuse, such as severe corrosion in the pump's aluminum block, shattered reservoir or severely damaged pressure relief valve(s) from DIY attempts to remove the pressure relief valves. Specifically, replacing damaged pressure relief valves incurs a surcharge of $150/ea - it's an involved process. There is no surcharge for rebuilding or replacing corroded motors on these pumps.

Return shipping within the US for $20 via FedEx 2-Day Service with signature required.

Send in your part first.