VALVETRAIN Overview
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 Max. width of 0.3 mm, or only the first 4 threads of the spark plug threads are cracked.
The cylinder head and guide frame must be replaced together.
Do not grind the valve seats in the cylinder head. Only hand lapping the valves is permitted.
Do not start the engine for approximately 30 minutes after installing the camshafts. The hydraulic lash adjusters must seat themselves (otherwise the valves will crash into the pistons).
After working on the valvetrain and adjusters, carefully rotate the crankshaft by hand at least 2 full revolutions before starting to be sure that the valves do not strike the pistons.
Always replace the gaskets and seals.
- Bolt
- 8 Nm + an additional 90° (1/4) additional turn.
- Always replace.
- Guide Frame
- Removing and installing, refer to CAMSHAFT .
- With integrated camshaft bearings.
- Clean the sealing surface, reworking is not permitted.
- Remove any old sealant residue.
- Exhaust Camshaft Sprocket
- Bolt
- 60 Nm + an additional 90° (1/4) additional turn.
- Always replace.
- Bolt
- 60 Nm + an additional 90° (1/4) additional turn.
- Always replace.
- Intake Camshaft Adjuster
- Seals
- For the camshaft adjuster.
- Note the installed position, refer to CAMSHAFT .
- Timing Chain
- Removing from the sprockets, refer to VALVE TIMING, ADJUSTING .
- Cylinder Head
- Do not grind the valve seats, only hand lapping is permitted.
- Roller Rocker Arm with Hydraulic Lash Adjuster
- Do not interchange.
- Lubricate the contact surface.
- Valve Retainers
- Upper Spring Seat
- Valve Spring
- Valve Stem Seal
- Removing and installing, refer to VALVE SHAFT SEALS .
- Valve Guide
- Checking, refer to VALVE GUIDE, CHECKING .
- Intake Valve
- Do not grind, only hand lapping is permitted.
- Valve dimensions, refer to VALVE DIMENSIONS .
- Valve guide, checking. Refer to VALVE GUIDE, CHECKING .
- Exhaust Valve
- Do not grind, only hand lapping is permitted.
- Valve dimensions, refer to VALVE DIMENSIONS .
- Valve guide, checking. Refer to VALVE GUIDE, CHECKING .
- Sealing Plug
- Always replace.
- Installing, refer to CAMSHAFT .
- Intake Camshaft
- Removing and installing, refer to CAMSHAFT .
- Check the radial clearance using Plastigage® (roller rocker arm is removed).
Wear limit: 0.1 mm
Run out: maximum 0.035 mm
Axial clearance: maximum 0.17 mm
- Exhaust Camshaft
- Removing and installing, refer to CAMSHAFT .
- Check the radial clearance using Plastigage® (roller rocker arm is removed).
Wear limit: 0.1 mm
Run out: maximum 0.035 mm
Axial clearance: maximum 0.17 mm