Valvetrain Overview

Valvetrain Overview

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

• The motor must not be started for about 30 minutes after installing the 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.






1 Bolt

• Replace

• Loosen and tighten with retainer (3036)

• Tightening specifications => [ (Item 3) Bolt ] Toothed Belt Drive Overview

2 Toothed Belt Camshaft Gear

3 Shaft Seal

• For exhaust camshaft

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

4 Cylinder Head

5 Valve Guide

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

6 Valve Stem Seal

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

7 Valve Spring

8 Valve Spring Plate

9 Valve Keys

10 Hydraulic Adjusting Elements

• With roller rocker lever and clip

• Mark the installed position for installation later

• Lubricate contact surfaces

11 Fitted Key

• Make sure it is secure

12 Exhaust Camshaft

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

• 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: 0.04 mm

13 Guide Frame

• With integrated camshaft bearings

• Do not rework the sealing surfaces, only clean them.

• Only replace together with the cylinder head.

14 Bolt

• Replace

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

15 Camshaft Adjuster

• Removing and installing, refer to => [ Camshaft Adjuster ] Camshaft Adjuster

16 Bolt

• Replace

• 20 Nm plus an additional 45° turn

17 Intake Camshaft

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

• 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: 0.04 mm

18 Chain Tensioner

• Removing, refer to => [ Camshaft Adjuster ] Camshaft Adjuster

• Before removing, secure with locking pin (T10115)

19 Drive Chain

20 Bolt

• Replace

• 9 Nm

• Self-locking

21 Bolt

• Tightening specifications => [ (Item 24) Bolt ] Cylinder Head Cover and Cylinder Head Overview

22 Camshaft Position Sensor (G40)

• Illustration does not correspond to version in vehicle

23 Exhaust Valve

• Do not rework, only lapping is permitted

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

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

24 Intake Valve

• Do not rework, only lapping is permitted

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

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

25 Cover

• Replace

• Removing: With the guide frame installed, pierce through one side of the cover with an awl and pry it out.

• Installing: Press in 1 to 2 mm without sealant using the thrust piece (3334)

Guide Frame Tightening Specifications and Sequence





- Replace the guide frame bolts.

- Tighten bolts in 3 stages in - 1 to 6 - sequence as follows:

- Install bolts by hand as far as stop.

• The guide frame must be in contact with the entire contact surface of the cylinder head.

- Tighten to 8 Nm.

- Tighten an additional 90°.