Coolant Bypass Tubes
Coolant Bypass Tubes are small metal tubes mounted to the front each cylinder head. They provide a mounting point for theBypass Hoses which carry hot coolant from the cylinder head to the upper coolant pipe.
Replacement
Because these tend to corrode, they should be replaced as part of the Timing Belt Service. Their installation requires a thin bead of liquid gasket around their mating surface, and their 2 x 10mm bolts snugged down (no torque spec is given).