Its not actually the tube but the plastic mounts that cause the problem MB# 116 180 01 84.
Fixing the condition will keep you from wearing cams and lifters but if you have a noise from this you have already damaged something. The rocker arm is usually the first to go and the groove that is first apparent is not visable with the rocker installed.
I would localize the noise before removing valve cover and then remove a few rocker arms in the general area untill you find the problem.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician