Contents: Removal ↡ Installation ↡
The cylinder head is disassembled only when the engine is cool. The intake and exhaust manifolds remain connected.
A defective sealing gasket can be identified by a number of signs.
Removal
1. Remove the air filter.
2. Drain the coolant, also from the crankshaft housing.
3. Disconnect the heating and cooling liquid hoses from the cylinder head, having first loosened the hose clamps.
4. Disconnect the battery ground (–) cable.
Warning! This will erase the radio's anti-theft code. See the instructions in the subsection on removing the battery.
5. Set the first cylinder of the engine to TDC ignition. To do this, set the gearbox to idle and tighten the parking brake. Turn the crankshaft until the markings match using a spanner with a SW27 socket for the central bolt of the crankshaft belt pulley in the direction of engine rotation, i.e. clockwise.
6. Pull out the locking tab of the fan shroud ring. Turn the cover in the direction of the "open" arrow and remove.
7. Remove the cylinder head cover.
8. Remove the chain tensioner.
Caution! The chain tensioner must be removed because when the top bar is removed it automatically pulls the ratchet. This can lead to excessive chain tension.
9. Unscrew the hot liquid recirculation pipe (25) from the shut-off cap (28), if present.
10. Disconnect the plug connections of the camshaft position sensor.
11. Unscrew the shock absorber tension roller from the front cover, push it down and turn it. Watch the adjacent washer, do not forget to install it during subsequent assembly.
12. Unscrew the bolts (arrow) of the front cover. Remove the cover with bolts (c).
13. Remove the coolant recirculator bolts (d), if equipped.
14. Mark the position of the camshaft gears in relation to the timing chain using a felt-tip pen or paint.
15. Loosen the bolts (3) of the diverter wheel (1), if present.
Attention! The bolt has a left-hand thread and is screwed in to the right.
16. Remove the parts together with the support (2).
17. Pull out the guide bar pins with a puller or other suitable tool.
18. Unscrew the camshaft adjuster anchor.
19. Remove the set of wires going to the engine, namely, loosen and remove all the wire connectors together with the plug connections.
20. Disconnect the cruise control mechanism, if equipped.
21. Disconnect the plug connection at the connector (X26/17). Disconnect the plug connection of the actuator of the electronic accelerator pedal (16/1x1) by pressing the locking latch (arrow). In this case, the plug rotates by 90° with the help of a spiral spring. Remove the engine wiring kit from the cable channel.
22. Unscrew the front exhaust pipe from the exhaust manifold.
23. Unscrew the air intake hose (1) on the cylinder head.
24. Disconnect the hose from the air intake check valve (arrow), unscrew the holder.
25. Unscrew the oil level gauge guide tube holder and the intake pipe support (arrows).
26. Disconnect the crankcase ventilation hose (43) from the combined support (17).
27. Open the fuel cap briefly to relieve excess pressure. Then unscrew the fuel lines (arrows).
28. Unscrew the vacuum hose (2) from the inlet pipe branch.
29. Disconnect the throttle control cable (30) from the throttle body.
30. For automatic transmission: unscrew the oil level measuring rod guide tube from the cylinder head.
31. Using a wrench with a socket, for example, HAZET 990SLg-12, unscrew the cylinder head bolts in the reverse order of the numbering in the figure, i.e. from 14 to 1. Cylinder 1 is located on the engine ventilation side.
32. Raise the cylinder head using a repair crane. To do this, thread a suitable cable or rope through the eyes.
Installation
1. Before installing the cylinder head and cylinder block, clean the sealing surfaces from sealant residues with a suitable scraper. Make sure that sealant residues do not get into the holes. Cover the holes with a rag.
2. Check the flatness of the cylinder head and engine block in the longitudinal and transverse directions with a steel ruler; correct if necessary (work for repair shops).
3. Check the cylinder head for scratches and the cylinder running surface for marks.
4. Thoroughly clean the cylinder head bolt holes from oil and other deposits.
5. Be sure to replace the cylinder head gasket.
6. Apply a new gasket without sealant so that the holes are not covered.
7. Before installing the cylinder head, check whether the camshafts are in the TDC position. In this position, the 4 mm diameter pins (1) can be inserted directly from the top edge of the cylinder head into the flanges of the camshaft gears. The crankshaft must also still be in the TDC position.
8. Install the cylinder head.
Attention! The cylinder head is fixed with dowel pins in the cylinder block.
9. Measure the length of the cylinder head bolts from the bottom edge of the bolt head, which when new is 160 mm long. If the length is 162.7 mm, replace the bolts.
10. Lubricate the cylinder head threads and bolt head mating areas. Install the bolts and tighten them by hand.
11. Tighten the cylinder head bolts in sequence from 1 to 14 in three stages. First, tighten the bolts with a torque wrench to 55 N·m. In the second stage, tighten all bolts from 1 to 10 by 90° with an open-end wrench. In the third stage, tighten bolts from 1 to 10 by another 90° with an open-end wrench.
Caution! Tighten the cylinder head bolts carefully. Check the accuracy of the torque wrench before tightening.
Caution: When tightening the bolts, to check the rotation angle, place the wrench handle along the engine and turn in one motion until the handle is positioned across the engine.
12. Place the control chain on the camshaft gears, observing the markings made during disassembly.
13. Remove the 4mm diameter pins from the camshaft flanges.
14. Connect the coolant hose to the coolant pump and secure with a hose strap.
15. Attach the throttle control cable and adjust it.
16. Connect the cruise control mechanism, if equipped.
17. Automatic transmission: Screw the oil level dipstick guide tube to the rear of the cylinder head.
18. Screw the return and direct fuel lines together, do not pinch the connection points.
19. Screw the brake booster vacuum line to the intake manifold. Place the crankcase ventilation hose onto the combination support and secure with a hose clamp.
20. Screw in the oil level gauge guide tube holder and the intake pipe support.
21. Install the air intake pipe with the connecting hose to the cylinder head. Use a new sealing ring between the pipe and the cylinder head.
22. Slide the electrical plug onto the engine wire harness and route it through the cable channel. Install the wire connector.
23. Screw the anchor to the camshaft adjuster.
24. Tighten the chain sprocket with support, if present, to a torque of 35 Nm (left hand thread).
25. Insert the guide rail pins into the engine block.
26. To seal the degreased groove of the control housing cover on the left and right at the junction (arrow) with the cylinder head, apply sealant, Mercedes-N001 9896120, according to the points. You can also use another sealant instead, for example, Omnifit FD 10 or Curil.
27. Insert a new seal without sealant into the degreased groove. Cover the front cover in the places where it fits to the cylinder head with sealant 002 989 00 20 10.
28. Install the front cover with the lower bolt (e) inserted. Tighten the lower bolts first to 20 Nm.
29. Screw on the camshaft adjustment device, seal the threads of the mounting bolts (f) with a sealant, such as Curil.
30. Lubricate the radial seal ring with engine oil and place it on the camshaft. To prevent damage to the seal ring at the edge, tape the camshaft connection elements beforehand, remove the tape after installing the seal ring. Specialized workshops have a 20 mm diameter insert sleeve instead.
31. Screw the shock absorber tensioner with the gasket on top.
32. Screw on the coolant recirculator if equipped.
33. Attach the electrical connectors to the position sensor and camshaft adjuster.
34. Install the chain tensioner.
35. Install the fan shroud ring, rotate it and lock it.
36. Install the cylinder head cover.
37. Connect the spark plugs to the ignition coils using plugs.
38. Install the air filter.
39. Screw the exhaust pipe to the manifold.
40. Connect the coolant hoses to the cylinder head and secure with clamps.
41. Fill with coolant.
42. Connect the battery.
43. Set the time on the clock.
44. Set the radio anti-theft code.
45. Warm up the engine to its operating temperature and check all connections for leaks.