Cylinder Head Assembly: Service and Repair
Removing And Installing/sealing Cylinder Head:
- Remove intake filter housing with air-mass flow sensor.
- Remove cylinder head cover.
Service and Repair
- Remove all spark plugs.
- Disconnect intake air manifold.
- Remove VANOS adjustment unit.
Service and Repair
- Detach cylinder recognition sensor.
- Drain off coolant and dispose of correctly.
Installation: [coolant drain plug].
Tightening Torque = 25 Nm.
- Vent cooling system and check for leaks.
- Remove exhaust pipe from exhaust manifold.
- Release water hose from branch flange.
- Unfasten heating intake and heating return hoses.
Removal:
- Removal of cylinder head is described separately from installation. Assembly sequence for removal and installation is different.
- Unfasten screws and remove shim from exhaust camshaft.
- Unfasten nuts from thrust washer (intake camshaft).
- Remove thrust washer (1).
- Remove plate spring (2).
- Remove thrust washer (3).
- Remove sprockets together with chain.
- Unscrew thrust washer bolts.
- Remove thrust washer.
- Remove sensor gear.
- Unscrew secondary chain tensioner.
- Unscrew chain guide.
- Unscrew primary chain tensioner (3).
Caution! Strong spring force.
- Remove spring (2) and plunger (1).
- Lift off sprocket with chain.
Caution! Protect timing chain to prevent it from falling.
- Unscrew timing case cover to cylinder head bolts.
Caution!
- Lift timing chain and hold under tension.
- Rotate engine on central screw counterclockwise to approx. 30° before TDC.
- This prevents contact between valves and pistons.
- Using special tool 11 2 250, release cylinder head bolts from outside to inside in sequence 14 to 1.
- Lift off cylinder head.
Installation:
- Installation of cylinder head is described separately from removal.
- Clean sealing faces of cylinder head and engine block, if necessary, remove traces of sealing compound with hardwood spatula. Ensure that no gasket debris drops into the oil and coolant ducts.
- Check that dowel sleeves are undamaged and correctly located.
- Apply permanently elastic sealing compound Drei Bond 1209 to joints to timing case cover.
- Fit new cylinder head seal.
CAUTION: The milled surface of the cylinder head must not be machined on the S50 US.
NOTE: Check that all washers are in place.
CAUTION:
- Cylinder head bolts must always only be used once.
- There must be no oil in the tapped holes of the engine block and the timing case cover. Risk of cracking and distorted tightening values.
- Install cylinder head and tighten down with new cylinder head bolts (lightly oiled) in the sequence 1...14.
NOTE:
- For torsion angle adjustment, connect special tool 11 2 250 to special tool 00 9 120.
Tightening Torque:
Jointing torque = 30 Nm
Torque angle = 90°
Torque angle = 90°
- Tighten screw connection for timing case cover on cylinder head.
- Unscrew three rear bolts for cylinder head cover mounting.
- If necessary, align the camshafts on the hexagon.
Caution!
- Do not damage the cylinder head.
- If necessary, machine open-end wrench accordingly.
- Rotate camshaft until cam tips on intake and exhaust camshafts of 1st cylinder point towards one another.
- Fit special tool 11 3 240 to camshafts on cylinder 6.
Note:
- Camshaft setting is OK if special tool 11 3 240 can lie flush on the cylinder head.
- Lift timing chain and hold under tension.
- Rotate engine enginewise from the 30° before TDC position up to TDC position.
- Hold crankshaft in TDC position with special tool 11 2 300.
Caution!
- Remove special tool 11 2 300 before switching on the engine.
- Fit primary timing chain to sprocket.
- Fit sprocket to exhaust camshaft with threaded bores on left side so that it is aligned to the deep bores.
- Install special tool 11 3 390.
- 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.
- Fit thrust washer and tighten down.
Tightening Torque:
Application torque = 5 Nm
Jointing torque = 20 Nm
Caution!
- Correctly install sprocket for intake camshaft.
- Flat side faces VANOS housing, Collar facing camshaft.
- Mount both sprockets together with chain. Slots centered.
- Fit thrust washer (3), approx. 2 mm.
- Install plate spring (2).
Note: Note installation direction of plate spring. Install large support diameter facing towards camshaft.
- Fit thrust washer (1), approx. 4 mm.
- Install nuts with screw securing adhesive Loctite 273.
- Tighten nuts.
Tightening Torque:
Application torque = 5 Nm
Jointing torque = 20 Nm
- Fit shim and screws to the exhaust camshaft.
- Fit screws with zero backlash: sprocket remains able to move.
- Install VANOS-adjustment unit.
- Assemble engine.