Camshaft Replace

REPLACING CAMSHAFT (M50 VANOS):
(Intake or exhaust side, as applicable)
The intake and exhaust camshafts can be changed in the vehicle.




Caution! Incorrect removal/installation without help of fixture could damage or break the camshaft. Valves could also be bent through contact with the piston crowns. Always note installation instructions and use specified special tools, procedures, and sequences.

Removal:

Removal of camshaft is described separately from installation. Assembly sequence for removal and installation is different.

Removing VANOS adjustment unit.




Remove the loosened screws from the exhaust sprocket wheel.




Unfasten nuts from intake camshaft.




Version without plate spring
Remove thrust washer (1).




Version with plate spring
(1) Thrust washer approx. 4 mm thick
(2) Plate spring
(3) Thrust washer approx. 2 mm thick
Remove thrust washers and plate spring.




Remove sprockets together with chain.




Unscrew thrust washer bolts. Remove thrust washer.




Remove sensor gear.




Unscrew secondary chain tensioner.




Unscrew chain guide.





Caution! Strong spring force.

Unfasten screw plug (3) from chain tensioner.
Remove spring (2) and piston (1).




Lift off sprocket with chain.




Protect timing chain to prevent it from falling.





Caution! To prevent damaging valves when fitting the camshaft no pistons should be in TDC position.

Pull back special tool 11 2 300 (setting mandrel) until the flywheel is no longer located in position.
Lift timing chain and hold under tension. Rotate engine counter-enginewise approx. 30° using the central screw.




Unscrew studs.




Prepare special tool 11 3 260.




Fit special tool 11 3 260 to cylinder head and screw into spark plug threads in cylinders 1 and 4.
Tightening torque:
M12x1.25 = 23+/-3 Nm
M14x1.25 = 31+/-2 Nm





Caution!

Bearing cover 1 on intake camshaft is centered on hollow dowels.
To prevent the intake camshaft from tilting in the bearing strip, remove bearing cover 1.




Turn the eccentric shaft to pre-tension the bearing cap Unfasten nuts on bearing cover.




Remove tension from the eccentric shaft and remove special tool 11 3 260.
Remove bearing covers and place to one side in orderly fashion. Remove camshaft.




If necessary, remove bearing strip.
Secure bucket tappets with special tool 11 3 250.
Lift out complete bearing strip with bucket tappet.

Note: Worn bucket tappets may only be reused in the same tappet bore.




Check bearing points on bucket tappets for signs of wear (scoring).




The bearing strips are marked with "A" for exhaust and "E" for intake.




Note centering dowels on retaining pins at bearing points 2 and 7.
Install bearing strips.




If necessary, replace splined shaft in intake camshaft.
Clamp camshaft with protective vice jaws.
Remove splined shaft.

Installation:
Tightening torque:
M14x1.5
Jointing torque = 40 Nm
Torque angle = 60°




Install camshafts.
Camshafts can be identified by the marks on the sprocket flanges.
A = Exhaust camshaft
E = Intake camshaft




Identification of camshafts:
AC = Exhaust camshaft M50 B20
EC = Intake camshaft M50 B20




Identification of camshafts:
AD = Exhaust camshaft M50 B25
ED = Intake camshaft M50 B25

Installation:
Installation of camshaft is described separately from removal. Assembly sequence for removal and installation is different.




Caution!

The bucket tappets expand when not subjected to load by the camshaft and therefore require some time before they can be pushed back down. During a rapid assembly sequence, the "closed" valves may still be open and be in contact with the piston.

You must adhere to the following waiting periods after installing the camshaft and before cranking the engine back to the TDC position.

- Room temperature (20°C) 4 mins
- 10°C ... 20°C 11 mins
- 0°C... 10°C 3O mins




Install camshafts with tips on intake and exhaust valve pointing towards 1st cylinder.




Fit bearing cover.

NOTE: The bearing covers are clearly marked and can be read from the exhaust end:
A1 ... A7 for the exhaust end
E1 ... E7 for the intake end




Fit special tool 11 3 260 to cylinder head and screw into spark plug threads in cylinders 1 and 4.
Tightening torque:
M12x1.25 = 23+/-3 Nm
M14x1.25 = 31+/-2 Nm





Turn the eccentric shaft to pre-tension the bearing caps.
Tighten down bearing cover.
Tightening torque:
M6 screw = 10 Nm
M7 screw = 15 Nm
M8 screw = 20 Nm

Remove special tool 11 3 260.




Caution!

Do not damage the cylinder head.
Machine open-end wrench accordingly if necessary.
Align camshafts with open-end wrench.




Fit special tool 11 3 240 to camshafts on cylinder 6.

NOTE: Camshaft adjustment is correct if special tool 11 3 240 bears on the cylinder head without gaps.




Lift timing chain and hold under tension.
Rotate engine from the 300 before TDC position engine-wise up to TDC position.
Secure crankshaft in TDC position with special tool 112300.

CAUTION! Remove special tool 11 2 300 (plug mandrel) before switching on the engine.




Fit primary timing chain to sprocket.
Fit sprocket to exhaust camshaft with threaded bores on left side aligned down the deep bores.




Install special tool 11 3 390 in chain tensioning sleeve (1).
Screw in the adjusting screw to touch the bow cover, but do not yet tighten it.




NOTE: Long bores in sprocket wheel are centered over threaded bores.




Install chain guide.




Install secondary chain tensioner.




Fit sensor gear to the intake camshaft.




CAUTION!

There is a danger of mixing up:
(1) Studs for cylinder-head covers.
(2) Studs for thrust washers and sprockets (version without plate spring).
(3) Studs for thrust washers and sprockets (version with plate spring).




Fit thrust washer and tighten down.
Tightening Torque:
Screw-in pin on camshaft = M7 20 Nm
Nut on screw-in pin = M6 10 Nm




CAUTION!

Correctly install sprocket for intake camshaft.
Flat side facing VAN OS housing, collar facing camshaft.




Mount both sprockets together with chain. Slots centered.




Version with plate spring:
Fit approx. 2 mm thickness of thrust washer (3).




Version with plate spring:

NOTE:

Note installation direction of plate spring.
Install large support diameter facing towards camshaft.
Install plate spring (2).




Version with plate spring:
Fit approx. 4 mm thickness of thrust washer (1) to the intake camshaft.




Version with plate spring:
Install nuts and tighten down.
Tightening Torque:
Screw-in pin on camshaft = M7 20 Nm
Nut on screw-in pin = M6 10 Nm





Version without plate spring:
Fit thrust washer (1) to the intake camshaft.




Version without plate spring:
Tighten down thrust washer (1) with nuts.
Tightening Torque:
Screw-in pin on camshaft = M7 20 Nm
Nut on screw-in pin = M6 10 Nm





Fit shim and screws to the exhaust camshaft.
Fit screws with zero backlash: sprocket remains able to move.

Installing VANOS adjustment unit,

Assemble engine.