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 regrind 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 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° (1/4) additional turn.
- Always replace.
- Guide Frame
- Removing and installing, refer to CAMSHAFTS .
- With integrated camshaft bearings.
- Clean the sealing surface, reworking is not permitted.
- Remove any old sealant residue.
- Sprocket
- For the exhaust camshaft.
- Bolt
- 60 Nm + 90° (1/4) additional turn.
- Always replace.
- Bolt
- 60 Nm + 90° (1/4) additional turn.
- Always replace.
- Camshaft Adjuster
- For the intake camshaft.
- Seals
- For the camshaft adjuster.
- Note the installed position, refer to CAMSHAFTS .
- Timing Chain
- Removing from the adjuster/sprocket, refer to VALVE TIMING, ADJUSTING .
- Cylinder Head
- Do not regrind 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 STEM SEALS .
- Valve Guide
- Checking, refer to VALVE GUIDE, CHECKING .
- Intake Valve
- Do not regrind, only lapping is permitted.
- For the correct valve dimensions, refer to VALVE DIMENSIONS .
- Valve guide, checking. Refer to VALVE GUIDE, CHECKING .
- Exhaust Valve
- Do not regrind, only lapping is permitted.
- For the correct valve dimensions, refer to VALVE DIMENSIONS .
- Valve guide, checking. Refer to VALVE GUIDE, CHECKING .
- Sealing Plugs
- Always replace.
- Installing, refer to CAMSHAFTS .
- Intake Camshaft
- Removing and installing, refer to CAMSHAFTS .
- Check the radial clearance using Plastigage (roller rocker arm removed).
Wear limit: 0.1 mm.
- Runout: Max. 0.035 mm.
- Axial clearance: Max. 0.17 mm.
- Exhaust Camshaft
- Removing and installing, refer to CAMSHAFTS .
- Check the radial clearance using Plastigage (roller rocker arm removed).
Wear limit: 0.1 mm.
- Runout: Max. 0.035 mm.
- Axial clearance: Max. 0.17 mm.