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 the camshafts because the hydraulic equalization elements must seat themselves.
• To ensure the valves do not strike the pistons when starting, carefully rotate the engine at least 2 full revolutions.
• Cylinder heads with cracks between the valve seats, or between the valve seat and the spark plug threads, can continue to be used without reducing the service life, as long as the cracks have a width of max. 0.3 mm, or only the first 4 threads of the spark plug threads are cracked.
• Cylinder head for cylinder bank 2 (left) is shown in illustration.
1 Sealing Plug
• Install with sealant; sealant, refer to the Parts Catalog
2 Cylinder Head
• Valve guides, checking, refer to => [ Valve Guides, Checking ] Testing and Inspection
3 Valve Stem Seal
• Replacing with the cylinder head installed, refer to => [ Valve Stem Seals, Cylinder Head Installed ] Valve Stem Seals, Cylinder Head Installed
• Replacing with the cylinder head removed, refer to => [ Valve Stem Seals with Cylinder Head Removed ] Valve Stem Seals With Cylinder Head Removed
4 Valve Spring
• Installed position, refer to => [ Installed Position of Valve Spring ]
5 Hydraulic Adjusting Elements
• Checking, refer to => [ Hydraulic Adjusting Elements, Checking ] Testing and Inspection
• Mark the installation position with paint for reinstallation
• Lubricate the running surfaces before installing
6 Valve Spring Plate
7 Valve Retainers
8 Roller Rocker Lever
• Different versions for the intake and exhaust side, do not interchange them
• Check roller for easy movement
• Lubricate the running surfaces before installing
• Clip to the hydraulic adjusting element - 5 - with the clip - 9 -
9 Clip
• Different versions for the intake and exhaust side, do not interchange them
• Make sure it is secure
10 Intake Camshaft
• With 3 camshaft sliders
• Do not disassemble
• Measuring axial play, refer to => [ Camshaft, Measuring Axial Play ] Testing and Inspection
• Removing and installing, refer to => [ Camshafts ] Service and Repair
• Measure radial clearance using Plastigage (roller rocker lever removed)
• Radial clearance at bearing - 24 mm diameter: 0.024 to 0.066 mm
• Radial clearance at bearing - 36 mm diameter: 0.032 to 0.078 mm
• Maximum run out: 0.04 mm
11 Bolt
• Replace
• Tightening sequence, refer to => [ Camshaft Guide Frame Tightening Specifications and Sequence ]
12 Camshaft Adjuster Actuator
13 Bolt
• 5 Nm
14 O-ring
• Replace
15 Guide Frame
• With integrated camshaft bearings
• Removing and installing, refer to => [ Camshafts ] Service and Repair
16 Compression Ring
17 Compression Ring
18 Exhaust Camshaft
• Measuring axial play, refer to => [ Camshaft, Measuring Axial Play ] Testing and Inspection
• Removing and installing, refer to => [ Camshafts ] Service and Repair
• Measure radial clearance using Plastigage (roller rocker lever removed)
• Radial clearance at bearing - 24 mm diameter: 0.024 to 0.066 mm
• Radial clearance at bearing - 36 mm diameter: 0.032 to 0.078 mm
• Maximum run out: 0.04 mm
19 Oil Strainer
20 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
21 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
• The illustration shows the guide frame for the left cylinder head.
- Replace the guide frame bolts.
- Tighten the bolts in 3 steps in the following sequence: - 1 to 21 -:
- Install bolts by hand as far as the stop.
• The guide frame must be touching the entire contact surface of the cylinder head.
- Tighten to 8 Nm.
- Tighten an additional 90°.
Installed Position of Valve Spring
• The tight spring coils - arrow - face toward the cylinder head.