Attention! If the tensioner loosens on the hexagon, then it must be removed without fail, otherwise the control chain will be over-tightened when screwing.
Removing
4 cylinder engine
1. Remove the hydraulic fan clutch.
2. Remove the cylinder head cover.
3. Remove the fan shroud.
4. Install the engine 20°below the TDC of ignition of the first cylinder. To do this, move the transmission to the idle position and apply the parking brake. Turn the crankshaft using a SW27 wrench at the center bolt of the crankshaft belt pulley in the direction of engine rotation, i.e. clockwise, until the markings match. The wrench bit length must be over 42mm.
5. Secure the exhaust camshaft against rotation. To do this, enter a suitable rod (Mercedes-N 111589011500) into the camshaft flange hole (78) through the hole in the camshaft bearing cap. If the chain is removed, fix the intake camshaft in the same way.
Attention! If you do not insert the locking pin (arrow), adjust the basic position of the camshaft.
6. Cover the generator with film or a rag.
6 cylinder engine
7. Remove the V-ribbed belt.
8. If necessary, loosen and move the air pump on top of the chain tensioner.
All engines
9. Loosen the screw plug (1), by turning one turn using a socket wrench SW10.
10. Unscrew the chain tensioner in combination with the part (14) and remove.
11. Unscrew the screw cap (1) with sealing ring (5). Remove compression spring (8) together with a pin (7).
12. Push back the push pin (10) with detent spring (9).
13. Thoroughly clean the parts separately with fuel and check for further suitability for use (risks, raid). Replace damaged parts, if necessary, replace the chain tensioner as a set.
Installation
1. Screw the chain tensioner housing to the engine block (14) with new sealing ring (15). The tightening torque for a 4-cylinder engine is 80 Nm, for a 6-cylinder engine it is 50 Nm.
2. Gather the details (7–10), as before dismantling them, and insert into the mounted chain tensioner.
3. Screw on the screw cap (1) with new sealing ring (5) with a torque of 40 Nm, while the spring is compressed.
4 cylinder engine
Attention! Remove the locking rod from the camshaft flange.
4. Install the cylinder head cover.
5. Remove the cover film from the generator.
6. Install the hydraulic fan clutch.
7. Start the engine and check the chain tensioner for leaks.
6 cylinder engine
4. Attach the air pump.
5. Put on the ribbed V-belt.
6. Start the engine and check the chain tensioner for leaks.