Has the insert in the top fallen out? If so you cannot tighten it enough. Assume it is leaking around the seal at the top? If so it suggests something further down the line is giving trouble,in years of 2.5 BMW diesel ownership, this is a new one and I suggest not a design defect,sure yours should have the plastic top not the metal one? Not sure how to check but suspect its the diameter, ask your local specialist NOT the stealer.
Have had several new seals and one new plastic top for this item. It stills leaks after a towing session or is worked hard, any clews as to a fix, thanks Bazz.
