The cooling system for the N54 engine in the 2008-2010 E82 135i/1M and E60 535i includes lines going into and out of each turbocharger. Over time, and with heat and vibration, one or more of these coolant pipes will leak. This is the return / outlet pipe for the rear turbo on the N54 in the 135i/1M and 535i (the E9X 335i coolant line is slightly different). It returns coolant to the engine block after running through the rear turbo. This is a Genuine BMW part with new o-rings included and comes with a two year warranty.
E82 / E88 (08-13) > 135i N54 (08-10)
E82 / E88 (08-13) > 1M (11-12)
E60 / E61 (04-10) > 535i
E60 / E61 (04-10) > 535xi
E89 Z4 (2009-2016) > Z4 sDrive35i
E89 Z4 (2009-2016) > Z4 sDrive35is