Camshaft Gear/Sprocket: Service and Repair
Removing and installing camshaft wheel
Tools and materials
Removing the camshaft wheel
Caution: Never twist the crankshaft the direction of movement!
Proceed carefully while working as otherwise the engine can be damaged!
Only turn the engine on the crankshaft and never on the camshaft as the timing chain can jump over!
After working on the camshaft wheels, the timing must be set and checked!
Please observe general warning notes and working regulations!
Note:
^ The setting is always checked simultaneously on both cylinder banks. Once a cylinder bank has been set, the crankshaft must not be turned to set the other cylinder bank!
^ The fastening screws of the chain sprockets must be replaced after removal.
^ The diamond washers of the chain sprockets must be replaced after removal.
^ The screws on the sprocket wheels are tightened by hand during assembly end are then loosened by one or two turns. This play is necessary so that the camshafts can still be turned.
^ The cylinder bank is set with the standard chain tensioner that is installed.
1. Remove the camshaft housing cover on both cylinder banks.
2. Using socket insert wrench 9714, turn the crankshaft until cylinder 1 is located in the ignition TDC.
3. Ensure that the cams on the 1st cylinder face upwards (ignition TDC).
View shows position of cams on cylinder 1
View shows position of cams on cylinder 5
Note: If the cams on cylinder 1 are not positioned as shown, check whether the crankshaft to be turned through another turn (360°)!
4. Insert fixing pin 9595/1 into the relevant groove in the timing chain housing cover through the bore provided in the crankshaft gearwheel.
View shows TDC position of crankshaft
5. Remove chain tensioner.
6. Loosen timing chain and pull upper plastic guide away from both pins. If necessary, turn ring wrench back and forth a little so that the timing chain has more play between the wheels.
Note: The fastening screw and diamond washer of the camshaft only needs to be replaced if it has been removed.
7. Only loosen the fastening screw of the camshaft adjuster (1 or 2 turns). To do this, hold the SW 32 hexagon of the camshaft adjuster and camshaft wheel against the corresponding camshaft with a ring wrench. Only unscrew pan-head screw M12 with the T60 socket wrench insert of the camshaft wheel.
8. Loosen the camshaft wheel from the back with a rubber hammer.
Caution: Do not let the diamond washer underneath the camshaft adjuster fall into the timing case.
Note: There is a diamond washer between the camshaft and camshaft wheel or camshaft adjuster. This is to be replaced after the corresponding wheel has been removed. If the fastening screw of the wheel is only loosened in order to adjust the timing (1 or 2 revolutions), the diamond washer does not need to be replaced.
9. With both hands, carefully remove the camshaft wheel from the chain.
10. Remove the diamond washer which is located underneath the camshaft adjuster.
Installing the camshaft wheel
Note: If the diamond washer and pan-head screw M12 are removed, replace the camshaft.
1. Replace the diamond washer and M12 pan-head screw which are located underneath the camshaft wheel.
2. Lift timing chain and place camshaft wheel carefully on the camshaft. In order to have more play in the timing chain, if necessary turn camshaft adjuster back and forth. Place timing chain on camshaft wheel.
3. Position new M12 fastening screw on camshaft wheel and screw in loosely (it must still be possible to turn the camshaft wheel).
4. Install chain tensioner.
Setting the timing
^ The crankshaft is positioned in the TDC and is fixed using fixing pin 9595/1 once the above preliminary check has been performed.
1. Turn the camshaft on the hexagon with an open-ended wrench until camshaft guide 9678 can be pressed back into the grooves of both camshafts simultaneously.
Figure shows the camshafts fixed with camshaft guide
Note: Cylinder banks 1-4 and 5-8 are adjusted without turning the crankshaft!
2. Then adjust the camshafts on cylinder bank 5-8. To do this, turn the hexagon with the open-ended wrench and fix it with camshaft guide 9678.
Correct positioning of cams in cylinder bank 5-8
Note: The fastening screws on the sprocket wheels do not need to be replaced after they have been undone. Only after removing.
3. Tighten all camshaft wheels with the M12 pan-head screw again. To do this, counter the hexagon (a/f 32) of the corresponding camshaft wheel with a ring wrench and tighten the M12 pan-head screw to 50 Nm (37 ft. lbs.) with the T60 socket wrench insert. Then remove camshaft guide 9678 and hold against the hexagon of the camshaft with an open-ended wrench. Tighten camshaft wheels with torque-angle wrench.
4. Remove fixing pin 9595/1 .
5. Turn engine through two turns (720°) and check the timing again.
6. Install the camshaft housing cover on both cylinder banks.
Tightening torques