Valve Train, Servicing
Valve train, servicing
Note:
^ Cylinder heads with cracks between valve seats or between valve seat and spark plug thread can still be used without loss of service life if the cracks are minute (maximum 0.3 mm width) or only the first four threads of a spark plug thread are cracked.
^ After installing camshafts, do not start engine for at least 30 minutes. The hydraulic valve lifters have to settle (otherwise valves will strike the pistons).
^ After working on the valvetrain, carefully rotate engine by hand at least 2 full revolutions to ensure that valves do not strike the pistons when starting.
^ Replace gaskets and O-rings.
^ Illustration depicts the left cylinder bank.
Part I
1. 10 Nm
2. Seals
^ Always replace, Refer to Seals and Gaskets, Engine, Camshaft oil Seal, Service and Repair
3. Housing
^ for camshaft adjustment valves
4. Gasket
^ Always replace
5. Exhaust camshaft
^ Checking axial clearance, Refer to Camshaft, Engine, Testing and Inspection
^ Removing and installing, Refer to Camshaft, Engine, Service and Repair
^ Check radial clearance using Plastigage (hydraulic valve lifters removed):
^ Wear limit: 0.1 mm
^ Max run-out: 0.01 mm
6. Piston rings for camshaft adjuster
^ Engage piston ring ends with each other
7. Intake camshaft
^ Checking axial clearance, Refer to Camshaft, Engine, Testing and Inspection
^ Removing and installing, Refer to Camshaft,Engine, Service and Repair
^ Check radial clearance using Plastigage (hydraulic valve lifters removed): Wear limit: 0.1 mm
^ Max run-out: 0.01 mm
8. 10 Nm
^ Tighten in several stages from inside out
9. Guide frame with integrated camshaft bearings
^ removing and installing Camshafts and camshaft adjuster, removing and installing, Refer to Seals and Gaskets, Engine, Camshaft Oil Seal, Service and Repair
10. Sensor wheel
^ Note position (notch on camshaft)
11. 23 Nm
12. Hydraulic valve lifter
^ Checking, Refer to Lifter Valve, Testing and Inspection
^ Removing and installing, Refer to Seals and Gaskets, Valve Guide Seals, Service and Repair
^ Do not interchange
^ Install with journal surface facing down
^ Before installing, check axial play of camshaft, Refer to Camshaft, Engine, Testing and Inspection
^ Oil contact surface
13. Valve keepers
14. Valve spring retainer
15. Valve spring
16. Valve stem oil seal
^ Always replace, Refer to Seals and Gaskets,Engine, Valve Guide Seal, Service and Repair
17. Camshaft Position (CMP) sensor
^ Cylinder bank 1 (right) Camshaft Position (CMP) Sensor-G40-:
^ Cylinder bank 2 (left) Camshaft Position (CMP) Sensor 2 -G163
18. 10 Nm
19. Camshaft Position (CMP) sensor for exhaust camshaft
^ Cylinder bank 1 (right) Camshaft Position (CMP) Sensor 3 -G300
^ Cylinder bank 2 (left) Camshaft Position (CMP) Sensor 4 -G301
20. O-ring
^ Always replace
21. 10 Nm
22. Camshaft Position (CMP)sensor housing
23. Gasket
^ Always replace
24. Cylinder head
^ Check valve guides, hand-lap valve seats
^ , Refer to Valve Guide, Testing and Inspection
^ Reface valve seats, Refer to Valve Seat, Service and Repair
25. Intake valve
^ Do not reface, only hand-lapping is permitted
^ Mark installation position for reinstalling
^ Valve dimensions
^ Check valve guides, hand-lap valve seats, Refer to Valve Guide, Testing and Inspection
26. Exhaust valves
^ Do not reface, only hand-lapping is permitted
^ Mark installation position for reinstalling
^ Valve dimensions - Fig 1
^ Check valve guides, hand-lap valve seats, Refer to Valve Guide, Testing and Inspection
Part II
1. Seals
^ Always replace, Refer to Seals and Gaskets, Engine, Camshaft Oil Seal, Service and Repair
2. Housing
^ for camshaft adjustment valves
3. O-Rings green
^ between solenoid valve housing and solenoid valves
^ Always replace
4. O-Rings
^ Black
^ Always replace
5. O-Rings green Always replace
6. 4 Nm
7. Camshaft adjustment valve - intake side
^ Cylinder bank 1 (right) Valve -1- for camshaft adjustment -N205
^ Cylinder bank 2 (left) Valve -2- for camshaft adjustment -N208
^ do not interchange with a valve for camshaft adjustment (exhaust side)
^ Note identification 12. 100 338
8. Gasket
^ Replace if damaged
9. Connector adapter
^ Must be replaced after disconnecting from camshaft adjustment valves
^ Carefully press onto harness connectors of camshaft adjustment valves until they engage
10. 4 Nm
11. Camshaft adjustment valve - exhaust side
^ Cylinder bank 1 (right) Camshaft
^ Adjustment Valve 1 (exhaust) -N318
^ Cylinder bank 2 (left) - Camshaft
^ Adjustment Valve 2 (exhaust) -N319
^ do not interchange with a camshaft adjustment valve (intake side)
^ Note identification 12. 100 339
12. Gasket
^ Always replace
13. 10 Nm
Fig. 1 Valve dimensions
Note: Valves must not be refaced Only hand-lapping is permitted
WARNING:
^ Sodium-filled exhaust valves must not be scrapped without first being properly treated.
^ Using a metal saw, the valves must be cut in half between the shaft center and valve plate. They must not come into contact with water while being cut. After cutting open valves, throw not more than 10 at a time into a bucket of water. Then step back. A sudden chemical reaction will occur during which the sodium filling is consumed.
^ Valves that have been treated in this manner can then be disposed of as normal scrap metal.
Fig. 2 Engage piston ring ends
^ Check whether the piston rings at the camshafts are installed and whether the piston ring ends are engaged with each other.
^ If necessary, engage the ends of the installed piston rings (arrows), as depicted in the illustration.