In vehicles with adjustable wheel suspension, unscrew the mounting bolts of the hydraulic suspension pump and remove the pump together with the pipelines.
On vehicles with air conditioning, remove the air conditioning compressor and set it aside.
Drain the coolant from the cooling system, remove the upper hose between the engine and the radiator.
Loosen the fastening of the right cover on the front side of the camshaft housing, as shown in Fig. 92.
Fig. 92. The arrows show the position of the covers on the camshaft housing. The right cover must be removed.
Remove the rocker arms as described in previous section.
Hold the right camshaft in the middle with a wrench to prevent it from turning and unscrew the sprocket mounting bolt. Turn the crankshaft to TDC of the first cylinder piston. Turn the shaft with a size 27 socket wrench placed on the central crankshaft pulley mounting bolt. Rotate the shaft only in the direction of travel.
Remove the chain tensioner and springs (see fig. 93).
Fig. 93. Removing the drive chain tensioner.
Remove the chain guide from the camshaft housing (section 3.10.4).
Pull the right camshaft back and remove the camshaft sprocket, then return the shaft to its original position.
Loosen the M8 bolts in the reverse order shown in Fig. 94. Do not unscrew the five bolts on the rear side and the two M8 bolts indicated by the arrows; they secure the cylinder head to the cylinder block.
Fig. 94. The order of tightening the bolts securing the camshaft housing. When removing the housing, unscrew the bolts in the reverse order.
Remove the camshaft housing together with the shafts.
When installing the camshaft housing, perform the following work:
Thoroughly clean the mating surfaces of the cylinders and camshaft housings and install a new gasket (metal foil). Carefully install the camshaft housing.
Lubricate the threads and bearing surfaces of the mounting bolts with engine oil and tighten the bolts.
Tighten the cylinder head mounting bolts in the following sequence:
- Hexagon socket head bolts with double flange in the bolt head: tighten all bolts in the sequence shown in Fig. 94 to a torque of 110 Nm, then turn the heads of bolts 2, 3, 5, 8, 10, 11, 12, 13 and 14 by a further 90° (quarter turn). Tighten bolts 1,4, 6, 7 and 9 located below to a torque of 110 Nm.
- Bolts with an internal hexagon in the bolt head: tighten all bolts according to the diagram in Fig. 58 to a torque of 70 Nm. When re-tightening, the torque should be 90 Nm, while bolts 1, 4, 6, 7 and 9 are first loosened and tightened again.
- Tighten the M8 bolts to 25 Nm. The M8 bolt next to bolt 12 can only be tightened with the camshaft sprocket removed. After tightening the mounting bolts, check the ease of rotation of the camshafts in the housing.
Place the sprocket on the right camshaft; at TDC of the piston of the first cylinder, the marks on the sprocket and the drive chain should be aligned.
[Material borrowed from an online resource: www.MercedesMan.ru]
Install the chain guide to prevent the chain from jumping off the sprockets.
Lubricate the bushing with engine oil and place it in the bearing housing.
Tighten the camshaft sprocket mounting bolt to 80 Nm, holding the shaft from turning.
Install the chain tensioner.
Perform the remaining work in reverse order. Adjust the valve clearance (section 3.13).