Engine Installed

Removing intake filter housing with mass air flow sensor, refer to Powertrain Management
Removing cylinder head cover, refer to Valve Cover
Removing all spark plugs.
Removing intake air manifold, refer to Intake Manifold
Removing VANOS adjustment unit, refer to Camshaft, Lifters and Pushrods, Camshaft, Engine.
Unfastening sensor for cylinder recognition, refer to Powertrain Management, Cylinder Identification Sensor, Service and Repair.





Drain off coolant and dispose of correctly.
Installation: Tightening torque, refer to Engine Specifications
Bleeding cooling system and checking for water leaks, refer to Cooling System
Remove exhaust pipe from exhaust manifold. Release water hose from branch flange. Unfasten heating intake and heating return hoses.
Removal of cylinder head is described separately from installation. Assembly sequence for removal and installation is different.





Unfasten screws and remove washer from exhaust camshaft.





Unfasten nuts from thrust washer (intake camshaft).





Remove thrust washer.





Remove sprockets and chain.





Remove secondary chain tensioning device.





Unscrew chain guide.





Lift off sprocket with chain.





Note: Secure chain with wire to prevent it from dropping.





Unscrew timing-case cover to cylinder head bolts.





Untighten cylinder head screws from outside to inside with special tool 11 2 250 in the sequence 14 ... 1. Lift off cylinder head.

Installation
Installation of cylinder head is described separately from removal. Assembly sequence for removal and installation is different.

Caution: Rotate engine on central screw counter-clockwise to approx. 30° before TDC.

This prevents contact between valves and pistons.
Clean sealing faces of cylinder head and crankcase; if necessary, remove traces of sealing compound with hardwood spatula. Make sure that no sealing compound falls into the oil or coolant channels.





Check that dowel sleeves are undamaged and correctly located.
Apply flexible sealing compound three Bond 1209 to timing case cover.
Fit new cylinder head gasket.





M52 For machined (milled) cylinder heads, the M52 is provided with a cylinder head gasket 0.3 mm thicker than usual.
S62

Caution: On the S52, the milled surface of the cylinder head must not be machined.





Note: Check that all washers are in place.

Caution: Cylinder head bolts must only ever be used once. No oil must be located in the threaded bores of the crankcase and the timing case cover. Risk of cracking, incorrect tightening values.





Fit cylinder head and tighten with new cylinder head screws (slightly oiled) in sequence 1 ... 14.





Note: For torsion angle adjustment, connect special tool 11 2 250 to special tool 00 9 120. Tightening torque, refer to Engine, Specifications.





Tighten screw connection for timing case cover on cylinder head.





Unscrew and remove the rear back screw pins which secure the cylinder head cover.





If necessary, align the camshafts on the hexagon.

Caution: Do not damage the cylinder head. Machine open-end wrench accordingly if necessary.





Rotate camshaft until cam tips on intake and exhaust camshafts of 1st cylinder point towards one another.





Fit special tool 11 3 240 to camshafts on cylinder 6.

Note: Camshaft setting is OK if special tool 11 3 240 can lie flush on the cylinder head.





Rotate engine from 30° before TDC position engine-wise to TDC position.
Hold crankshaft in TDC position with special tool 11 2 300.

Caution: Remove special tool 11 2 300 before switching on the engine.





Fit primary timing chain to sprocket.
Fit sprocket to exhaust camshaft with threaded bores on left side aligned down the deep bores.





Install special tool 114 220. Screw in the adjusting screw to touch the tensioning rail, but do not yet tighten it.





Note: Long bores in sprocket are now centered.





Install chain guide.





Install secondary chain tensioner.





Caution: Fit sprocket to intake camshaft correctly. Flat side facing VANOS adjustment unit. Collar facing camshaft.





Mount both sprockets together with chain. Slots centered.





Fit thrust washer to the intake camshaft and tighten down with nuts. Tightening torque, refer to Engine, Specifications





Fit washer and screws to the exhaust camshaft. Fit screws with zero backlash: sprocket remains able to move. Installing VANOS adjustment unit, refer to Camshaft, Lifters and Pushrods, Camshaft, Engine.