Valve Spring: Service and Repair
11 34 715 - Replacing all valve springs (N73)
Special tools required:
- 11 0 346 11 0 340 Accessories
- 11 9 000 11 9 000 Cylinder Head Expander Tool
- 11 9 014 11 9 000 Cylinder Head Expander Tool
- 11 9 470 11 9 470 Support
Necessary preliminary tasks:
- Remove left cylinder head cover [1][2]Removing and Installing/Sealing Left Cylinder Head Cover.
- Remove right cylinder head cover Removing and Installing/Sealing Right Cylinder Head Cover.
- Remove inlet and exhaust adjustment unit on left side Removing and Installing/Replacing Inlet and Exhaust VANOS on Left Side (N73).
- Remove inlet and exhaust adjustment unit on right side Removing and Installing/Replacing Inlet and Exhaust VANOS on Right Side (N73).
- Remove left intermediate lever Removing and Installing/Replacing Left Intermediate Levers (N73).
- Remove right intermediate lever Removing and Installing/Replacing Right Intermediate Levers (N73).
- Remove left exhaust camshaft Removing and Installing/Replacing Left Exhaust Camshaft.
- Remove right exhaust camshaft Removing and Installing/Replacing Right Exhaust Camshaft.
- Remove left cylinder head Removing and Installing Left Cylinder Head (N73).
- Remove right cylinder head Removing and Installing Right Cylinder Head (N73).
Important!
Used rocker arms may only be reused in the same position.
Remove rocker arms of inlet camshaft and set aside in neat order.
Place bearing bracket with inlet camshaft and eccentric shaft as illustrated on special tool 11 9 470 11 9 470 Support.
Illustrations show cylinders 7 to 12.
Rocker arms (1) are now freely accessible.
Installation:
Rocker arm (1) is attached with a spring clamp on hydro-element.
Before installing bearing bracket, make sure rocker arms (1) are correctly positioned.
Observe rocker arm tolerance classes as illustrated (1 to 4).
Important!
Only rocker arms of the same tolerance class may be fitted in each cylinder on the inlet side.
Place cylinder head on special tool 11 9 000 11 9 000 Cylinder Head Expander Tool.
Press down special tool 11 9 014 11 9 000 Cylinder Head Expander Tool valve spring.
Special tool 11 0 346 11 0 340 Accessories old version
Align special tool 11 0 346 11 0 340 Accessories in direction of valve shaft.
Press down valve spring on spring cap from above and remove valve keys.
Important!
Valve springs of exhaust and inlet camshafts are different.
Incorrect installation is possible.
Mixing up the valve springs will result in engine damage.
Valve spring (1), inlet side.
Valve spring (2), exhaust side.
Valve spring (2), exhaust side, is approx. 4 mm longer.
Install valve springs so that larger diameter points to spring plate at bottom.
Only the diameter is decisive for the correct installation of the valve springs.
Color coding (1) is on lower end of valve spring.
Arrangement:
1) - Valve
2) - Valve stem seal with spring plate, bottom
3) - Valve spring
4) - Spring plate, top
5) - Valve keys
Assemble engine in reverse sequence to its disassembly.
Installation:
Clean all bearings and cams of inlet and exhaust camshafts and lubricate with engine oil.