Overview - VALVETRAIN
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CAUTION:
Risk of damaging valves and piston heads after working on valve train.
- The motor must not be started for about 30 minutes after installing camshafts because the hydraulic equalization elements must seat themselves.
- To ensure valves do not strike pistons when starting, carefully rotate engine at least two full revolutions.
NOTE:
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.
The illustration shows the cylinder bank 2 cylinder head (left).
- Sealing Plugs
- Install with sealant.
- Cylinder Head
- Valve guides, checking. Refer to VALVE GUIDES, CHECKING .
- Valve Stem Seal
- Replacing with the cylinder head installed. Refer to VALVE STEM SEALS, REPLACING, CYLINDER HEAD INSTALLED .
- Replacing with the cylinder head removed. Refer to VALVE STEM SEALS WITH CYLINDER HEAR REMOVED, REPLACING .
- Valve Spring
- Installed position. Refer to Fig 2
- Hydraulic Adjusting Element
- Clipped into roller rocker lever -8-
- Checking. Refer to HYDRAULIC ADJUSTING ELEMENTS, CHECKING .
- Mark the installed position for installation later
- Lubricate the running surfaces before installing
- Valve Spring Retainer
- Valve Retainers
- Roller Rocker Lever
- Mark the installed position for installation later
- Check roller for easy movement
- Lubricate the running surfaces before installing
- To assemble, clip onto the hydraulic adjusting element -9- with securing clip -5-
- Clip
- Not available individually
- Make sure it is secure
- Intake Camshaft
- Removing and installing. Refer to CAMSHAFT, REMOVING AND INSTALLING .
- Axial play, measuring. Refer to CAMSHAFT, MEASURING AXIAL CLEARANCE .
- Radial play, measuring. Refer to CAMSHAFT, MEASURING RADIAL CLEARANCE .
- Maximum run out: 0.04 mm
- Bolt
- Replace
- Tightening specification and sequence. Refer to Fig 3.
- Guide Frame
- With integrated camshaft bearings
- Removing and installing. Refer to CAMSHAFT, REMOVING AND INSTALLING .
- Flat Ring
- Flat Ring
- Exhaust Camshaft
- Removing and installing. Refer to CAMSHAFT, REMOVING AND INSTALLING .
- Axial play, measuring. Refer to CAMSHAFT, MEASURING AXIAL CLEARANCE .
- Radial play, measuring. Refer to CAMSHAFT, MEASURING RADIAL CLEARANCE .
- Maximum run out: 0.04 mm
- Oil Screen
- Installed depending on the version.
- Intake valve
- Do not rework, only lapping is permitted
- Mark the installed position for installation later
- Checking. Refer to VALVES, CHECKING .
- Valve dimensions. Refer to VALVE DIMENSIONS
- Valve guides, checking. Refer to VALVE GUIDES, CHECKING .
- Exhaust valve
- Do not rework, only lapping is permitted
- Mark the installed position for installation later
- Checking. Refer to VALVES, CHECKING .
- Valve dimensions. Refer to VALVE DIMENSIONS
- Valve guides, checking. Refer to VALVE GUIDES, CHECKING .
- The tight spring coils -arrow- face toward the cylinder head.
NOTE:
The guide frame for the left cylinder head camshaft is shown in the illustration. The right cylinder head is identical.
Replace the bolts that were tightened with an additional turn.
-- Tighten the bolts in three steps and in the sequence shown:
| Step | Bolts | Tightening Specification/Additional Turn |
|---|---|---|
| 1. | -1 to 21- | Install the bolts all the way in by hand
|
| 2. | -1 to 21- | 8 Nm |
| 3. | -1 to 21- | Turn an additional 90°. |