Removing and Installing Cylinder Head
WM 157019 Removing and installing cylinder head on 4.8 liter DFI engines
Information
Component changes for model year 2009 as of October 2008
Information:
Always read the information concerning modified tightening specifications and component changes relating to repairs provided for specific engine numbers in the Information section.
Preliminary work
Preliminary work
Information:
If more extensive work is planned, e.g. if the entire cylinder head is to be replaced, the exhaust manifolds, fuel injectors, high pressure pump or vacuum pump must also be removed.
1. Remove the engine.
2. Remove the engine and place it on the assembly support.
3. Remove the turbocharger from the exhaust manifold on V8 turbo engines.
4. Remove the intake air distributor.
5. Remove the fuel distribution pipe.
6. Remove the timing case cover.
7. Remove the timing chain.
8. Remove the deflection rail.
9. Remove the camshafts.
Information
Component overview
Cylinder head 1 to 4
1 - Cylinder head 1 to 4
2 - Cylinder head gasket 1 to 4
3 - Screw, M8 - Tightening torque: 23 Nm (17 ftlb.)
4 - Lid
5 - Stopper
6 - Stopper
7 - Restrictor for valve lift control - Tightening torque: 1.5 Nm (1.0 ftlb.)
8 - Cylinder-head screws
9 - Spark plug; for refitting - Tightening torque: 25 Nm (19 ftlb.)+3 Nm (+2 ftlb.); if fitting new spark plugs Tightening torque: 30 Nm (22 ftlb.)+3 Nm (+2 ftlb.)
Cylinder head 5 to 8
1 - Cylinder head 5 to 8
2 - Screw plug - Tightening torque: 5 Nm (3.5 ftlb.)
3 - Spark plug; for refitting - Tightening torque: 25 Nm (19 ftlb.)+3 Nm (+2 ftlb.); if fitting new spark plugs - Tightening torque: 30 Nm (22 ftlb.)+3 Nm (+2 ftlb.)
4 - Cylinder head gasket 5 to 8
5 - Stopper
6 - Restrictor for valve lift control - Tightening torque: 1.5 Nm (1.0 ftlb.)
7 - Stopper
8 - Lid
9 - Cylinder head screws
Tightening sequence for cylinder head
Bolts 1 to 10
- 1st initial tightening Tightening torque: 30 Nm (22 ftlb.); 2nd initial tightening - Tightening torque: 50 Nm (37 ftlb.); loosen by 2 turns - Torque angle: 720°; 1st turn - Tightening torque: 30 Nm (22 ftlb.); 2nd turn - Tightening torque: 30 Nm (22 ftlb.); 3rd turn and final tightening (torque angle) - Torque angle: 110°
Removing cylinder head
Removing cylinder head
1. Remove the vent line between the oil mist separator and cylinder head. To do this, unscrew the fastening screws -3-.
Vent line
1 - Vent line to cylinder head/crankcase/oil pump
2 - O-ring
3 - Screw, M6 x 12
4 - Check valve
A - Direction of travel
2. Remove vent line.
2.1. Unscrew fastening screws -1-.
2.2. Unclip vent line -2- from the cable duct and remove it -arrow-.
Removing vent line
3. Expose the engine wire harness close to the vacuum pump.
Unclipping engine wire harness close to vacuum pump
Unclipping engine wire harness at the rear right
4. Unclip the engine wire harness close to the high pressure pump.
4.1. Unclip the engine wire harness at the retaining clips -arrows A-.
4.2. Unscrew the screw socket -arrow B-.
Unclipping engine wire harness close to high pressure pump
5. Lift the wire harness up and out at the cylinder heads -arrow-
Removing engine wire harness
6. Remove mounting saddle at the front -8- (cylinder bank 1 to 4 shown). This hides the cylinder head screws underneath.
Camshafts, cylinder bank 1 to 4
1 - Camshaft (outlet)
2 - Camshaft (intake)
3 - Hydraulic valve for variable valve lift control
4 - Screw, M5 x 12
5 - Switching tappet (oil with engine oil)
6 - Bucket tappet (oil with engine oil)
7 - Stopper
8 - Mounting saddle 1 to 4
9 - Stopper
10 - Bearing locations (oil with engine oil)
A - Direction of travel
7. Remove front M8 screw securing the cylinder head of cylinders 1 to 4 to the crankcase. -3-
Cylinder head 1 to 4
8. Remove cylinder head screws in the opposite order to the tightening sequence shown. Remove cylinder head. If necessary, remove the valve lifters now and lay them aside in the correct order.
Tightening sequence for cylinder head
9. Remove cylinder head gasket.
10. Remove cylinder head for cylinders 5 to 8 in the same way.
Cylinder head 5 to 8
Installing cylinder head
Installing cylinder head
Caution:
Leaks due to components being at too low a temperature or at different temperatures!
If components that are cold or at different temperatures are sealed together by the application of sealant, adhesion problems and leaks can arise due to the build up of condensation water or component distortion.
- Components must have reached at least 17°C throughout.
- Components must not be too hot (distortion).
- Spare parts that are stored in the cold or heat (strong sunlight), must be brought to room temperature or the same temperature as other parts before installation.
Information:
All sealing surfaces must be clean and free of grease!
It is essential to work carefully!
Tightening sequences and tightening torques must be observed!
1. Replace cylinder head gasket.
2. Place cylinder head gasket correctly, i.e. according to specifications, onto the straight pins on the engine crank housing. This must be done in such a way that the marking 'Top' can be read -see illustrations-.
Cylinder bank 1 - 4
Cylinder bank 5 - 8
3. Fit cylinder head. Insert cylinder head screws (screws can be re-used). Refer to the component overview above for tightening specifications.
Cylinder head 1 to 4
1 - Cylinder head 1 to 4
2 - Cylinder head gasket 1 to 4
3 - M8 screw
4 - Lid
5 - Stopper
6 - Stopper
7 - Restrictor for valve lift adjustment
8 - Cylinder-head screws
9 - Spark plug
Cylinder head 5 to 8
1 - Cylinder head 5 to 8
2 - Screw plug
3 - Spark plug
4 - Cylinder head gasket 5 to 8
5 - Stopper
6 - Restrictor for valve lift adjustment
7 - Stopper
8 - Lid
9 - Cylinder head screws
4. Fit front M8 screw to secure the cylinder head of cylinders 1 to 4 to the crankcase. -3-
Cylinder head 1 to 4
5. Fit the mounting saddle at the front -8- (cylinder bank 1 to 4 shown).
Camshafts, cylinder bank 1 to 4
1 - Camshaft (outlet)
2 - Camshaft (intake)
3 - Hydraulic valve for variable valve lift control
4 - Screw, M5 x 12
5 - Switching tappet (oil with engine oil)
6 - Bucket tappet (oil with engine oil)
7 - Stopper
8 - Mounting saddle 1 to 4
9 - Stopper
10 - Bearing locations (oil with engine oil)
A - Direction of travel
6. Secure wire harness to the engine.
6.1. Position and lay engine wire harness on the engine housing -arrow-.
6.2. Tighten fastening screws. - Tightening torque: 10 Nm (7.5 ftlb.)
Securing engine wire harness on engine housing
7. Clip in engine wire harness at the rear right using the retaining clip -arrow-.
Clipping in engine wire harness at the rear right
8. Clip in engine wire harness close to the vacuum pump.
8.1. Clip in engine wire harness using the retaining clip -arrow A-.
8.2. Slide engine wire harness onto the holder -arrow B-.
Clipping in engine wire harness close to the vacuum pump
9. Clip in engine wire harness close to the high-pressure pump.
9.1. Screw in and tighten the screw socket -arrow A-. - Tightening torque: 23 Nm (17 ftlb.)
9.2. Clip in engine wire harness using the retaining clips -arrows B-.
Clipping in engine wire harness close to the high-pressure pump
10. Install vent line.
10.1. Position vent line -1- and clip it into the cable duct -arrow-.
10.2. Fit the fastening screws -2-. - Tightening torque: 10 Nm (7.5 ftlb.)
Installing vent line
11. Insert oil vent line at the firewall side of cylinder 5 and screw it on. Lightly grease the sealing ring.
Vent line
1 - Vent line to cylinder head/crankcase/oil pump
2 - O-ring
3 - Screw, M6 x 12 - Tightening torque: 10 Nm (7.5 ftlb.)
4 - Check valve
A - Direction of travel
Subsequent work
Subsequent work
1. Fit deflection rail.
2. Install camshafts.
3. Fit timing chain.
4. Fit timing case cover.
5. Set the timing.
6. Fit the fuel distribution pipe.
7. Fit intake air distributor.
8. Fit the turbocharger on V8 turbo engines.
9. Take the engine from the assembly support and mount it on the transmission.
10. Install the engine.