In cars with air conditioning, remove the compressor and set it aside along with the pipes.
Unscrew the chain tensioner plug with an internal Allen key of 17 mm size (see fig. 84) and remove the spring.
Insert a 10mm Allen key into the chain tensioner and turn it to the right to remove the tensioner.
After removing the tensioner, disassemble it and then place the pusher in the installation position "A" (see fig. 85 and 86).
Fig. 85. Chain tensioner.
A - installation position,
B - position during operation.
Fig. 86. Chain tensioner in the installation position.
If the chain tension is weakened with the tensioner installed, for example, when removing the camshaft sprockets, remove the tensioner and put the pusher in the installation position. When replacing the tensioner, install it with the pusher assembly.
Install the chain tensioner in the reverse order and tighten the plug with a new sealing ring to a torque of 50 Nm.
(Article borrowed from the web portal: «Mercedesman.ru»)