Removing and Installing or Replacing VANOS Adjustment Unit

Removing fan wheel with fan coupling, refer to Cooling System, Fan Clutch, Service and Repair.
Removing cylinder head cover, refer to Cylinder Head, Valve Cover, Service and Repair.
Removing spark plugs, refer to Powertrain Management, Ignition System, Spark Plugs, Service and Repair.

Removal:
Removal of VANOS adjustment unit is described separately from installation. Assembly sequence for removal and installation is different.





Unscrew oil pressure pipe.
Disconnect solenoid-valve plug-in connection.





Unscrew suspension eye.





Remove cable channel.





Pull off plastic cover for intake camshaft.





Rotate engine engine-wise until cam tips on intake and exhaust camshafts on 1st cylinder face one another.





Pull dust guard out of the special tool bore.





Secure crankshaft in TDC position with special tool 11 2300.

Caution: Remove special tool 11 2 300 before starting engine.





Unscrew studs.





Locate camshafts with special tool 11 3 240.





Unfasten screw plugs.





Unfasten sprocket screws on exhaust camshaft.





Press down top of secondary chain tensioner and lock with special tool 11 3 292.





Unscrew nuts.





Version with plate spring
Fit special tool 11 5 490 to exhaust camshaft gear.
Using special tool 11 5 490, rotate sprockets and secondary chain clockwise, at the same time removing the VANOS adjustment unit.





Version without plate spring

Note: On the version without plate spring, the VANOS adjustment unit can be removed without special tool.

Removing VANOS adjustment unit.

Installation:
Installation of VANOS adjustment unit is described separately from removal. Assembly sequence differs between removal and installation.





Version with plate spring
Rotate sprockets and secondary chain clockwise with special tool 11 5 490 until detent position is reached.





Version without plate spring

Note:
^ On version without plate spring, special tool is not required.
^ Turn sprockets with mounted secondary chain clockwise as far as stop.





Press back spline shaft on adjustment unit (1) as far as detent in housing (2).





Note dowel sleeves (1).
Seal contact edges along joint between cylinder head and VANOS adjustment unit with Drei Bond 1209 sealing compound (or equivalent). Replace seal.





Fit VANOS adjustment unit.
Rotate spline shaft (1) until internal spline engages.





Version with plate spring
Fit special tool 11 5 490 to exhaust camshaft.
Rotate chain and gears with special tool 11 5 490 counterclockwise until spline shaft engages in internal spline of sprocket (2).





Caution: Always ensure that the FIRST suitable tooth engages.





Version with plate spring
Slide VANOS adjustment unit towards cylinder head.
Guiding the helical bevel splined shaft into the helical bevel splined sprocket turns the sprockets with mounted chain counter-clockwise.
Rotate chain and gears with special tool 11 5 490 counterclockwise.





Version without plate spring
Rotate chain and gears by hand counter-clockwise until spline shaft locates in internal spline of sprocket (2).

Caution: Always ensure that the FIRST suitable tooth engages.





Version without plate spring
Slide VANOS adjustment unit towards cylinder head. Guiding the helical bevel splined shaft into the helical bevel splined sprocket turns the sprockets with mounted chain counter-clockwise. Guide the chain with sprockets in counter-clockwise direction by hand.





Tighten down VANOS adjustment unit.





Remove special tool 11 3 292.





Caution:
^ Strong spring force. Unfasten cylinder for chain tensioning piston.





Install special tool 11 4 220.
Fit adjusting screw to tensioning rail.





Tighten tensioning rail with special tool 11 4 220 by rotating the adjusting screw with special tool 00 9 250 or preload with standard torque wrench to 1.3 Nm.





Tighten sprocket on exhaust camshaft in two passes.
Tightening torque, refer to Engine, Specifications.





Remove special tool 11 3 240.





Remove special tool 11 2 300.

Note: If work was carried out on the camshafts previously, rotate engine twice engine-wise, then check camshaft setting.





Secure crankshaft with special tool 11 2 300 in TDC position of 1st cylinder.

Caution: Do not turn the engine back.

Remove special tool 11 2 300 before switching on the engine.





Apply special tool 11 3 240 on camshafts.
The camshaft setting is OK if special tool 11 3 240 locates flush against the cylinder head.
Remove special tool 11 3 240.





Relieve tension on special tool 11 4 220 and remove.





Install cylinder for chain tensioning piston:

M52
refer to Timing Components, Timing Chain Tensioner, Service and Repair.

S52
refer to Timing Components, Timing Chain Tensioner, Service and Repair.





Install plugs with new sealing rings.
Tightening torque, refer to Engine, Specifications





Check function of VANOS adjustment unit.
Fit special tool 11 3 450 with banjo bolt on oil pressure line.
Connect up compressed air (2 to 8 bar).





Measure gap (x) between secondary tensioner and edge of sensor gear.
Note down distance 1.





Connect special tool 12 6 410 to plug connection for VANOS solenoid valve.
Connect positive clip to battery connection point.
To adjust camshaft, connect negative terminal to vehicle earth.

Caution: Reversing terminals on special tool will destroy installed diode on VANOS solenoid valve. Solenoid valve remains serviceable but current spikes can give rise to faults in vehicle circuit.





Measure gap (x) between secondary tensioner and edge of sensor gear.
Note down distance 2.
Determine control travel:
Distance 2 - distance 1 = length of stroke.

Caution: If the adjustment travel is less than 8.5 mm, the VANOS adjustment unit must be removed and readjusted.





Remove special tools 11 3 450 and 12 6 410.





Fit cable duct.





Fit suspension lug.





Fit oil pressure line with new seals.
Tightening torque, refer to Engine, Specifications.
Install solenoid-valve plug-in connection.





Remove special tool 11 2 300 (setting mandrel).
Assemble engine.