E39 Touring power tailgate weak: top up and bleed the hydraulic pump reservoir before replacing parts
When the power tailgate loses its lift, check the fluid first. The pump sits to one side of the boot. Remove its hold-down bolts, unclip the plastic reservoir (held by a hose clip), clean and refill it with transmission fluid, refit it, then raise and lower the tailgate by hand a few times to bleed. Some pumps have a top-up screw; the poster's 2003 car did not. Only if that fails do you need a rebuilt pump or cylinder.
Parts / numbers mentioned: transmission fluid (ATF)
- PistonHeadsE39 Electric Tailgate - Where's the hydraulic reservoir? ↗checked 2026-10-01