If you remove the valve cover & the chain is VERY tight..then most likely the tensioner wasn't installed correctly.

That tensioner MUST be installed 1 piece at a time. 1st the tensioner must be installed & then the closing cap & spring must be installed.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator