Hack Engineering Coolant Sensor Tube for BMW S54 engines. This tube replaces the factory tube which runs from the thermostat housing to the water rail. Unlike the original, this tube has a pair of 1/8″ NPT ports for the addition of aftermarket coolant temperature sensors. CNC-machined from billet aluminium right here in Sussex. Uses factory o-rings at either end. Comes fitted with two 1/8″ NPT bungs. Replaces BMW part number 11537830710. *prototype part shown in fitted image. 3/16″ hex size for bungs.