Valvetrain Overview

Valvetrain Overview


Risk of damaging valves and piston heads after working on the valve train.

• The motor must not be started for about 30 minutes after installing camshafts because the hydraulic equalization elements must seat themselves.

• To ensure valves do not strike pistons when starting, carefully rotate the engine at least 2 full revolutions.

• 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 (max. 0.3 mm width) or only the first four threads of a spark plug thread are cracked.

• The illustration shows the cylinder bank 2 cylinder head (left).






1 Sealing Plug

2 Valve Stem Seal

• Replace, refer to => [ Valve Stem Seals with Cylinder Head Installed, Replacing ] Valve Stem Seals With Cylinder Head Installed, Replacing, => [ Valve Stem Seals with Cylinder Head Removed, Replacing ] Valve Stem Seals With Cylinder Head Removed, Replacing

3 Valve Spring

• Installed position, refer to => [ Installed Position of Valve Spring ]

4 Hydraulic Adjusting Elements

• Clipped into roller rocker lever - 8 -

• Checking, refer to => [ Hydraulic Adjusting Elements, Checking ] Testing and Inspection

• Mark the installation position with paint for reinstallation

• Lubricate the running surfaces before installing

5 Valve Spring Plate

6 Valve Retainers

7 Clip

• Not available individually

• Make sure it is secure

8 Roller Rocker Lever

• Mark the installation position with paint for reinstallation

• Check roller for easy movement

• Lubricate the running surfaces before installing

• Clip to the hydraulic adjusting element - 4 - with the clip - 7 -

9 Intake Camshaft

• Removing and installing, refer to => [ Camshafts ] Service and Repair

• Measuring axial play, refer to => [ Camshaft, Measuring Axial Clearance ] Camshaft, Measuring Axial Clearance

• Radial clearance, measuring, refer to => [ Camshaft, Measuring Radial Clearance ] Camshaft, Measuring Radial Clearance

• Maximum run out: 0.04 mm

10 Gasket

• Replace

11 Guide Frame

• With integrated camshaft bearings

• Removing and installing, refer to => [ Camshafts ] Service and Repair

12 Bolt

• Replace

• Tightening specification and sequence, refer to => [ Camshaft Guide Frame Tightening Specifications and Sequence ]

13 Camshaft Position (CMP) Sensor 2 (G163)

14 Bolt

15 O-ring

• Replace

16 Bolt

17 Camshaft Position (CMP) Sensor 4 (G301)

18 O-ring

• Replace

19 Compression Ring

• For camshaft adjuster

20 Exhaust Camshaft

• Removing and installing, refer to => [ Camshafts ] Service and Repair

• Measuring axial play, refer to => [ Camshaft, Measuring Axial Clearance ] Camshaft, Measuring Axial Clearance

• Radial clearance, measuring; refer to => [ Camshaft, Measuring Radial Clearance ] Camshaft, Measuring Radial Clearance

• Maximum run out: 0.04 mm

21 Cylinder Head

• Valve guides, checking, refer to => [ Valve Guides, Checking ] Testing and Inspection

22 Intake Valve

• Do not rework, only lapping is permitted

• Mark the installed position for installation later

• For the correct valve dimensions, refer to => [ Valve Dimensions ] [1][2]Specifications

• Valve guides, checking, refer to => [ Valve Guides, Checking ] Testing and Inspection

23 Exhaust Valve

• Do not rework, only lapping is permitted

• Mark the installed position for installation later

• For the correct valve dimensions, refer to => [ Valve Dimensions ] [1][2]Specifications

• Valve guides, checking, refer to => [ Valve Guides, Checking ] Testing and Inspection

Camshaft Guide Frame Tightening Specifications and Sequence





• Replace bolts that are tightened to the specification.

- Tighten the bolts in 3 steps in the sequence shown:






Installed Position of Valve Spring





• The tight spring coils - arrow - face toward the cylinder head.