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 width of maximum 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 mill the valve seats in the cylinder head. Only lapping the valves is permitted.
Do not start the engine for approximately 30 minutes after installing the camshafts. The hydraulic adjusting elements must seat themselves (otherwise the valves will seat themselves on the pistons).
After working on the valvetrain and lifters, carefully rotate the crankshaft by hand at least 2 full revolutions before starting to be sure that valves do not strike the pistons.
Always replace the gaskets and seals.
- Bolt
- 8 Nm + 90° turn
- Replace after removing
- Guide Frame
- Removing and installing, refer to CAMSHAFT .
- With integrated camshaft bearings
- Clean sealing surface, reworking is not permitted.
- Remove old sealant residue.
- Chain Sprocket
- For the exhaust camshaft
- Bolt
- 60 Nm + 90° turn
- Replace after removing
- Bolt
- 60 Nm + 90° turn
- Replace after removing
- Camshaft Adjuster
- For the intake camshaft
- Seals
- for camshaft adjuster
- Installation position, refer to CAMSHAFT
- Timing Chain
- Removing from chain sprockets (refer to VALVE TIMING, ADJUSTING ), adjusting valve timing
- Cylinder Head
- Do not re-grind valve seats, only hand-lapping is permitted.
- Hydraulic Valve Play Balancing Element
- Do not interchange
- Lubricate contact surface
- Valve Retainers
- Upper Valve Spring Retainer
- Valve Spring
- Valve Stem Seal
- Replacing, refer to VALVE SHAFT SEAL
- Valve Guide
- Checking, refer to VALVE GUIDES, CHECKING
- Intake Valve
- Do not rework, only lapping is permitted
- Valve dimensions, refer to VALVE DIMENSIONS .
- Valve guides, checking, refer to VALVE DIMENSIONS .
- Exhaust Valve
- Do not rework, only lapping is permitted
- Valve dimensions, refer to VALVE DIMENSIONS .
- Valve guides, checking, refer to VALVE GUIDES, CHECKING .
- Plug
- Installing, refer to CAMSHAFT .
- Replace after removing
- Intake Camshaft
- Removing and installing, refer to CAMSHAFT .
- Check radial clearance using Plastigage® (roller rocker lever removed)
Wear limit: 0.1 mm
- Run-out: maximum 0.035 mm
- Axial play: maximum 0.17 mm
- Exhaust Camshaft
- Removing and installing, refer to CAMSHAFT .
- Check radial clearance using Plastigage® (roller rocker lever removed)
Wear limit: 0.1 mm
- Run-out: maximum 0.035 mm
- Axial play: maximum 0.17 mm