Removing and Installing Camshaft Timing Gear (Sprocket)
WM 150719 Removing and installing camshaft timing gear (sprocket) on 4.8-liter DFI enginesPreliminary work
Preliminary work
1. Remove cylinder head cover (valve cover) on both cylinder banks.
2. The spark plugs should be removed to make the crankshaft easier to turn.
Removing camshaft timing gear (sprocket)
Removing camshaft timing gear (sprocket)
Caution:
Damage to engine by turning crankshaft against the rotation direction of the engine (engine assembled)!
- Never rotate crankshaft against the operating direction if the timing drive mechanism is mounted (timing chain jumps over).
- Proceed carefully while working as otherwise the engine can be damaged.
- Always turn the engine on the crankshaft and never on the camshaft as the timing chain may jump over.
- After working on the camshaft wheels, the timing must be set.
- Please observe general warning notes and working regulations.
Staking bore 45° before TDC of cylinder 1
1. Turn the crankshaft at the vibration balancer so that the vibration balancer's staking bore -2- is located approx. 45° in front of the lower staking point on the timing-case cover -1-.
2. Loosen all four screws of the camshafts (sprockets and camshaft controllers) (undo one to two turns). Counter at the respective hexagon.
Loosening camshafts (illustrated with timing-case cover removed)
Information:
Move the camshafts carefully. Do not force.
Turn in the other direction if necessary.
Information:
A data matrix coding is shown on the staking dihedron of the camshafts. This is a square black/white dotted marking used for electronic identification purposes during the production process. This marking can be used as an aid when inserting the camshafts into the cylinder head. All four camshafts press against the valves the least when the data matrix coding is facing upwards during installation.
3. Turn all four camshafts so that all the data matrix codings at the adjustment edges point upwards approximately simultaneously (this enables the camshafts to exert the minimum amount of pressure on the valve lifters). The camshafts are turned at their hexagon using an appropriate open-ended wrench. Observe identical information on assembling the camshafts.
Camshaft position for cylinders 1 to 4
Camshaft position for cylinders 5 to 8
Hexagon at camshaft
4. Remove chain tensioner.
5. Loosen timing chain.
6. Remove screw for the respective camshaft timing gear -3- and carefully take out camshaft timing gear -2- with both hands under the timing chain. Loosen the camshaft timing gear using a rubber hammer carefully from behind if necessary.
Timing chain and sprockets
1 - Double-chain camshaft drive
2 - Camshaft sprocket
3 - Screw, M12 x 140 Tighten completely after setting timing.
4 - Deflector rail
5 - Screw, M8 x 35
6 - Camshaft-to-camshaft guide pad
A - Direction of travel
Installing camshaft timing gear (sprocket)
Installing camshaft timing gear (sprocket)
Caution:
Damage to engine by turning crankshaft against the rotation direction of the engine (engine assembled)!
- Never rotate crankshaft against the operating direction if the timing drive mechanism is mounted (timing chain jumps over).
- Proceed carefully while working as otherwise the engine can be damaged.
- Always turn the engine on the crankshaft and never on the camshaft as the timing chain may jump over.
- After working on the camshaft wheels, the timing must be set.
- Please observe general warning notes and working regulations.
Timing chain and sprockets
1 - Double-chain camshaft drive
2 - Camshaft sprocket
3 - Screw, M12 x 140 Tighten completely after setting timing.
4 - Deflector rail
5 - Screw, M8 x 35
6 - Camshaft-to-camshaft guide pad
A - Direction of travel
1. Lift timing chain and place camshaft timing gear carefully on the camshaft. In order to have sufficient play in the timing chain, turn the loosened camshaft controller back and forth if necessary. Place timing chain on camshaft timing gear.
2. Fit screw for camshaft timing gear and screw it in loosely.
3. Screw in the four screws of the sprockets and camshaft controller as far as possible (it must still be possible to turn the sprockets and camshaft controller to adjust the timing).
4. Set the timing. Do not tighten the sprockets and camshaft controller to the final tightening until after the timing has been set.
Subsequent work
Subsequent work
1. Fit spark plugs.
2. Fit valve cover.