Getting ready to replace my shock and tensioner assembly this weekend. The MB mechanic who helped me diagnose recommended the following:
Remove the top radiator support,
Remove the shroud and fan,
Remove the pulleys on the water pump and steering pump,
Remove the belt,
Take the bolt out of the tensioner,
Remove the two bolts from the steering pump for the front support bracket,
Loosen the tensioner,
Unbolt the top of the shock,
Work with it - it will come out.
Might help if you want to get the shock out to remove the tensioner as well. Have a look - might need replacing. Mine is squeaking - tough to locate that noise sometimes.
Hope this helps
93 190e 2.6 92k
81 240D 209k
89 Range Rover 140k