Valvetrain Overview

Valvetrain Overview

Risk of damaging valves and piston heads after working on valvetrain.

• 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 engine at least 2 full revolutions.

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






1 Valve

• Do not reface, only lapping is permitted

• Mark the installed position for installation later

• Checking, refer to => [ Valves, Checking ] Testing and Inspection

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

2 Cylinder Head

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

• The valve seat may not be reworked due to a close tolerances.

3 Valve Stem Seal

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

4 Valve Spring

5 Valve Spring Plate

6 Valve Retainers

7 Camshaft Seal

• Removing and installing, refer to => [ Camshaft Seal ] Service and Repair.

8 Bolt

9 Nut

10 Guide Frame

• With integrated camshaft bearings

• Removing and installing, refer to => [ Left Cylinder Head Camshaft ] Left Cylinder Head Camshaft, => [ Right Cylinder Head Camshaft ] Right Cylinder Head Camshaft

11 Intake Camshaft

• Removing and installing, refer to => [ Left Cylinder Head Camshaft ] Left Cylinder Head Camshaft, => [ Right Cylinder Head Camshaft ] Right Cylinder Head Camshaft

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

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

• Maximum run out: 0.01 mm

12 Exhaust Camshaft

• Removing and installing, refer to => [ Left Cylinder Head Camshaft ] Left Cylinder Head Camshaft, => [ Right Cylinder Head Camshaft ] Right Cylinder Head Camshaft

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

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

• Maximum run out: 0.01 mm

13 Roller Rocker Lever

• Removing and installing, refer to => [ Left Cylinder Head Camshaft ] Left Cylinder Head Camshaft, => [ Right Cylinder Head Camshaft ] Right Cylinder Head Camshaft

• Mark the installed position for installation later

• Check roller for easy movement

• Lubricate the running surfaces before installing

14 Hydraulic Adjusting Elements

• Mark the installed position for installation later

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

• Lubricate the running surfaces before installing

15 Pressure Relief Valve 1.0 Bar

• 25 Nm

• For the lubricating points in the cylinder head

Left Cylinder Head Guide Frame, Tightening Specifications and Sequence





- Tighten the bolts and nuts in 2 steps in the sequence shown:






Right Cylinder Head Guide Frame, Tightening Specifications and Sequence





- Tighten the bolts and nuts in 2 steps in the sequence shown: