Figure 97. Location of the chain tensioner (1)
The chain tensioner can be easily removed, however it is recommended to have a hand press to perform subsequent installation of the tensioner on the engine. A benchtop drill press may also come in handy. The tensioner plug has two hexagons for the key: large and small. Only the large hexagon should be unscrewed with a wrench. If you start to unscrew the small hex key, the chain tensioner may fall apart inside. Figure 97 shows the location of the chain tensioner plug on the engine installed in the vehicle. If there is any doubt about the serviceability of the tensioner, it should be replaced with a new one.
Before installing a new tensioner, it must be filled with oil. To do this, it is necessary to lower the tensioner with the pressure rod into a container with engine oil. The oil level should reach the mark above the hexagon flange. Then place the vessel together with the tensioner inside under a hand press (or on a benchtop drilling machine) and press the push pin until it stops 7–10 times.
Figure 96. Camshaft drive mechanism assembly: 1 - crankshaft sprocket; 2 - chain tension shoe; 3 - chain tensioner; 4 — camshaft drive sprocket; 5 - chain tensioner; 6 — fuel pump drive sprocket; 7 - chain tensioner; 8 — oil pump drive chain tensioner lever; 9 — oil pump drive sprocket
After filling the tensioner with oil, its compression should be checked: it should be done slowly, evenly and only with the application of a certain amount of force. After this, you should install the sealing gasket and install the tensioner in its place in the engine. It should be tightened to a torque of 80 N·m. The tensioner push rod should sit on the tension shoe as shown in the figure 96.
(Original source of information MercedesMan.ru)