That's a great tip I also had success with hose clamp. It's a moronic design with plastic to plastic connection no seal. Both our e53 were leaking there at about 130,000 miles and 15-16 years old. The upper o-ring was much worse sprayed so much the siphon jet stopped working at about 1/4 and 3/8 of a tank.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)