Removing Camshafts

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→ Clean or replace dirty components.

Information 

Specifications for wrench sizes (a/f specifications) for screw heads are described as follows:

• Torx screws: (E..) for external Torx, (T..) for internal Torx. 
• Hexagon-head bolts (internal and external hexagon): Wrench size (a/f) 

Overview of cylinder head 4-6: 

Fig 1: Exploded View Of Camshafts/Cylinder Head Components
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1. Intake camshaft 4-6
2. Outlet camshaft 4-6
3. Camshaft mounting saddles
4. External Torx screw, M6 x 37
5. Bearing saddle (upper part)
6. Bearing saddle (lower part)
7. External Torx screw, M6 x 55
8. Dowel sleeves for cylinder head
9. Bucket tappets (exhaust)
10. Switchable bucket tappets (intake)
11. Friction plate (diamond washer)
12. Sprocket 4-6
13. Central screw M12 x 1.5 x 60
14. Camshaft actuator
15. Hexagon
16. Central screw M12 x 1.5 x 110
17. Position of matching number on cylinder head

Information 

• The camshafts can only be removed in the overlapping position at the top dead center of pistons 1 or 4. 
• Only at this position can you be sure that the valves are not touching against the pistons and cannot be damaged when the engine turns. 

1. Turn the engine at the assembly support so that the cylinder bank to be worked on is at the top.
2. Use special tool turning device 9773 -1- to turn the crankshaft clockwise  at the vibration damper as far as the TDC marking on cylinder 1/4  .
   Fig 2: Identifying Vibration Damper Bolt

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   1. 2.1. Fix the vibration damper in place above the staking bore using a locating pin 9595/1 -2-  .
   2. 2.2. Check the position of the data matrix code (inset) on both camshafts. These must be facing the observer at overlapping position.
      Fig 3: Identifying Matrix Code Mark On Camshafts

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      Fig 4: Identifying Matrix Code Mark On Camshafts

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3. Check cam position on cylinders 1 and 4.
   1. 3.1. Overlap of cylinder 1:  The cams must be facing downwards at an angle to the cylinder head wall -arrows-  .
      1. Outlet camshaft 1-3
      2. Intake camshaft 1-3
         Fig 5: Locating Outlet And Intake Camshaft On Cylinder (1)

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   2. 3.2. Overlap of cylinder 4:  The cams are facing each other and are at a slight angle with respect to the spark-plug recess -arrows-  .
      Fig 6: Locating Outlet And Intake Camshaft On Cylinder (4)

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4. Remove central screws on camshaft timing gears.
   Fig 7: Identifying Central Screws On Camshaft Timing Gears

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5. Loosen internal Torx central screw (T55, M12 x 1.5 x 60) on the outlet sprocket. To do this, counter with special tool holding wrench 9775 -1-  .
   Fig 8: Removing Outlet Sprocket Threaded Joint

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6. Loosen internal Torx central screw (T55, M12 x 1.5 x 110) on the camshaft controller. To do this, counter with a long open-ended wrench (a/f 32) -1-  .
   Fig 9: Removing Camshaft Controller Threaded Joint

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7. Remove the chain tensioner (position on engine in installation position).
   1. 7.1. Cylinder bank 1-3:  Chain tensioner sitting on underside of the crankcase.
   2. 7.2. Cylinder bank 4-6:  Chain tensioner sitting on top of cylinder head.
   3. 7.3. Replace sealing ring.
8. Remove four external Torx screws (E10, M6 x 55) on the bearing saddle -2-  .
   1. 8.1. Then remove the external Torx screws (M6 x 37) for the mounting saddles from the outside to the inside -1-  .
      Fig 10: Identifying Camshaft Mounting Saddles

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9. Lift camshafts out of the cylinder head.
   1. 9.1. Unscrew central screw on the camshaft controller.
   2. 9.2. Lift the camshaft controller -1-  with the intake camshaft and pull the shaft -2-  to the flywheel side using one hand. Pay particular attention to the friction plate when doing so. Lift the timing chain and remove the camshaft controller.
      Fig 11: Identifying Intake Camshaft With Camshaft Controller

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   3. 9.3. Join the controller to the intake camshaft again for storage. Tighten screw only slightly.
   4. 9.4. Remove outlet camshafts complete with the sprocket.
      Fig 12: Identifying Outlet Camshaft With Sprocket

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   5. 9.5. Lay the timing chain in the chain housing in the cylinder head.
10. Replace the friction plates in the sprocket and at the intake camshaft. 

    Information 

    • The camshaft controller must not be cleaned in a parts washer. 
    • Only the outside can be cleaned using a clean, lint-free cloth. 
11. Clean the components.
    1. 11.1. Do not clean the camshaft controller in a parts washer.
12. Check camshafts and bearing points in the cylinder head for obvious indents and scoring.
    1. 12.1. There must be no obvious scoring on the bearing points and cams. 
    2. 12.2. Up to 1 mm of wear (breakage) is permissible on the cam tips. 
13. Check cam running surface of the bucket and switching tappets for obvious indents or scoring.
    1. 13.1. There must be no obvious scoring. 
14. If an unacceptable degree of wear is found in accordance with the specifications in points  13 and 14, replace the component.