Removing Camshafts

→ Protect components from dirt and contamination.

→ 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) 

Information 

When loosening the camshaft actuators, a second person must counter with the relevant tool.

1. Check crankshaft position.
   1. 1.1. The first piston (viewed from the belt side) must be at ignition TDC on cylinder bank 1-3.
   2. 1.2. Turn the engine clockwise at the crankshaft pulley until the second marking on the pulley -2-  is aligned with the joint -arrow-  of the crankcase halves. Then check the cam position.
      Fig 1: Identifying TDC Marking On Pulley

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   3. 1.3. Ignition TDC position of cylinder 1:  the cams on the outlet and intake camshaft of cylinder 1 are facing outward at a slant -arrows-  .
      Fig 2: Locating Cam Positions Of Cylinder 1 At Ignition TDC

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   4. 1.4. Unscrew three Torx screws (M6 x 25) -2-  on the guide rail -1-  and remove the rail.
2. Remove chain tensioner (check the marking, mark installation position).
   1. 2.1. Unscrew two external Torx screws (E10, M6 x 20) on the chain tensioner cover and remove cover. Then remove the chain tensioner.
      Fig 3: Identifying Chain Tensioner

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3. Cylinder bank 1-3 only:  Remove driver -1-  for vacuum pump.
   1. 3.1. Unscrew two internal Torx screws (T30, M6 x 55) -2-  and remove the driver.
   2. 3.2. Replace screws.
      Fig 4: Identifying Driver For Vacuum Pump On Outlet Camshaft For Cylinder Bank 1-3

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4. Loosen central screws (M12 x 130) on the camshaft controllers.

   No pressure should be applied to the timing chain, so counter at all times. 

   1. 4.1. Outlet camshaft:  Internal serration cheese head bolt -2-  , counter at the hexagon driver (a/f 24) using the special tool holding wrench 9653/2  .
   2. 4.2. Intake camshaft:  Hexagon-head bolt (a/f 16) -1-  , counter at the hexagon piece with a long ring wrench (a/f 30).
   3. 4.3. Replace internal serration bolt and hexagon-head bolt. 
      Fig 5: Identifying Central Screws On Camshaft Actuators

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5. Remove camshaft actuators.
   1. 5.1. Lift up the timing chain and remove the actuators one by one.
   2. 5.2. Replace friction plates (diamond washers).

   Information 

   • Only remove oil guide housing from the camshaft if the camshaft has to be replaced. 
   • Use a magnetic socket-wrench insert when unscrewing the cylinder screws. 
   • The oil guide housings of cylinders 1 - 3 and 4 - 6 differ in height. 
     Fig 6: Identifying Oil Guide Housings

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6. Loosen oil guide housing -2-  (do not remove it).
   1. 6.1. Unscrew three hexagon socket head bolts (a/f 4, M5 x 10) -3-  .

      Be careful not to let the bolts fall into the chain slot! 

      Tool recommendation: Magnetic socket-wrench insert, hexagon socket a/f 4 

   1. Timing chain
   2. Oil guide housing
   3. Cheese head bolt M5 x 10, hexagon socket a/f 4
      Fig 7: Identifying Oil Guide Housing And Timing Chain

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7. Remove camshaft housing.
   1. 7.1. Unscrew the external Torx screws (E10, M6 x 30) on the housings evenly from the inside out -1 to 3-  .
      Fig 8: Identifying Camshaft Housings

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   2. 7.2. Carefully lift up the camshaft housing. The housings must not be confused (note the marking).
8. Remove thrust bearing cover.
   1. 8.1. Unscrew six external Torx screws (E10, M6 x 30) -1-  and lift the thrust bearing cover up and off (note the marking).
      Fig 9: Identifying Thrust Bearing Cover Screws (Cylinder Bank 4-6)

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9. Lift out the camshafts and hold the timing chain while doing this.
   1. 9.1. Place the camshafts on a clean surface.
   2. 9.2. Place the timing chain in the chain housing.
10. Remove hydraulic tappets if necessary and check them for signs of wear.
    1. 10.1. If you remove them, have a clean surface prepared on which you can write details of each one → Example of laying aside bucket tappets  . Note the installation position of the bucket tappets in the housing.
       Fig 10: Noting Installation Position Of Bucket Tappets

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