What is/was broken on your E53 today?

[oldskewel]

Originally Posted by Fifty150hs

Check the O ring on the reservoir as well. Mine was groaning as well. Opened it up and it had low fluid. also had a fine mist of fluid all over the housing. checked the o ring - hard as a rock. New o ring, no leak and no more groaning.

Same exact experience for me. Weird how the mist just somehow saturates the area with a film and you can't find a point source for it. But yes, simple replacement of the reservoir cap o-ring fixed it for me too.

BTW - tip for those cases where you've got a non-sealing seal and can't immediately replace with new ... sometimes one side of the gasket is harder than the other, so just flipping it over and reinstalling it will improve or even fix things for a while.