Camshaft, Lifters and Push Rods: Service and Repair
Valvetrain Assembly 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 max. 0.3 mm, or only the first 4 threads of the spark plug threads are cracked.
Risk of damaging valves and piston heads after working on valvetrain.
• 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 2 full revolutions.
• Cylinder head for cylinder bank 2(left) is shown in illustration.
1 Sealing plug
2 Valve stem seal
• replacing with the cylinder head installed => [ Valve Stem Seals, Cylinder Head Installed ] Valve Stem Seals, Cylinder Head Installed
• replacing with the cylinder head removed => [ Valve Stem Seals, with Cylinder Head Removed ] Valve Stem Seals, With Cylinder Head Removed
3 Valve spring
• Installed location => [ Installed position of valve spring ]
4 Hydraulic adjusting element
• clipped into roller rocker lever - item 8 -
• checking => [ Hydraulic Adjusting Elements, Checking ] Testing and Inspection
• Do not interchange
• Lubricate contact surface
5 Valve spring plate
6 Valve keys
7 Securing clip
• Check for secure seat
8 Roller rocker lever
• Do not interchange
• Check roller for easy movement
• Lubricate contact surface
• To assemble, clip onto the hydraulic adjusting element - item 4 - using a circlip - item 7 -.
9 Intake camshaft
• Removal and installation => [ Camshafts ] Service and Repair
• Checking axial play => [ Camshafts, Checking Axial Clearance ] Testing and Inspection
• Check radial clearance using Plastigage (roller rocker lever removed)
• Radial clearance at bearing-dia. 24 mm: 0.024 to 0.066 mm
• Radial clearance at bearing-dia. 36 mm: 0.032 to 0.078 mm
• Run-out: max. 0.04 mm
10 Gasket
• Replace
11 Bearing bracket
• With integrated camshaft bearings
• Removal and installation => [ Camshafts ] Service and Repair
12 Bolt
• Tightening order => [ Guide frame tightening sequence ]
13 Camshaft position (CMP) sensor 2 (G163)
14 Bolt
• 9 Nm
15 O-ring
• Replace
16 Bolt
• 9 Nm
17 Camshaft position (CMP) sensor 4 (G301)
18 O-ring
• Replace
19 Compression ring
• for camshaft adjuster
20 Exhaust camshaft
• Removal and installation => [ Camshafts ] Service and Repair
• Checking axial play => [ Camshafts, Checking Axial Clearance ] Testing and Inspection
• Check radial clearance using Plastigage (roller rocker lever removed)
• Radial clearance at bearing-dia. 24 mm: 0.024 to 0.066 mm
• Radial clearance at bearing-dia. 36 mm: 0.032 to 0.078 mm
• Run-out: max. 0.04 mm
21 Cylinder Head
• Check valve guides => [ Valve Guides, Checking ] Testing and Inspection
22 Intake valve
• Do not rework, only grinding is permitted
• Mark installed position for re-installation
• Valve dimensions => [ Valve Dimensions ] Specifications
• Check valve guides => [ Valve Guides, Checking ] Testing and Inspection
23 Exhaust valve
• Do not rework, only grinding is permitted
• Mark installed position for re-installation
• Valve dimensions => [ Valve Dimensions ] Specifications
• Check valve guides => [ Valve Guides, Checking ] Testing and Inspection
Guide frame tightening sequence
- Tighten bolts in 2 stages in - 1 to 24 - sequence as follows.
- Install bolts by hand as far as stop.
- Tighten the bolts to 8 Nm.
Installed position of valve spring
• The tight spring coils - arrow - face toward cylinder head.