Removal and Replacement
11 12 100 Removing and installing/sealing cylinder head (N51)Special tools required:
Important!
Aluminum-magnesium materials.
No steel screws/bolts may be used due to the threat of electrochemical corrosion.
A magnesium crankcase requires aluminum screws/bolts exclusively.
Aluminum screws/bolts must be replaced each time they are released.
Aluminum screws/bolts are permitted with and without color coding (blue).
For reliable identification:
Aluminum screws/bolts are not magnetic.
Jointing torque and angle of rotation must be observed without fail (risk of damage).
Necessary preliminary tasks:
^ Remove exhaust system.
^ Drain coolant.
^ Drain engine oil.
^ Remove both exhaust manifolds.
^ Remove intake plenum.
^ Detach coolant hoses from cylinder head.
^ Remove cylinder head cover.
^ Remove intake and exhaust camshaft adjusters.
Important!
Fit new cylinder head screws.
Do not wash off bolt coating.
There must be no fluids or contaminants in any of the threaded holes for the cylinder head bolt connections.
(Risk of corrosion and cracking).
Release screws (1).
Unclip timing chain module (2) at separation point (3) and remove towards top.
Do not allow timing chain to drop down.
Installation:
Only during assembly is the timing chain lifted out with a hook.
Unfasten screws (2).
Remove eccentric shaft sensor (1) towards front.
Release screw (1).
Remove magnet wheel (2) towards front.
Important!
Magnet wheel (2) is extremely magnetic.
Important!
After removing, pack magnet wheel (1) away immediately in a plastic bag (2) for safety reasons.
Magnet wheel must be protected against metal chips.
Pre-tension eccentric shaft (1) upwards in direction of arrow.
Remove min stop screw between 1st and 2nd cylinders.
Tightening torque: 11 37 6AZ.
Release screws (1).
Tightening torque: 11 12 3AZ.
Screw (2) can only be released when the chain module is pressed forward slightly.
Important!
Secure screw (2) with a gripper against falling out and remove.
Installation:
Replace aluminum screws.
Important!
Different screw heads
M 10 screw (1) is released with special tool 11 8 580.
M 9 screw (2) is released with special tool 11 4 420.
Note:
Graphic shows camshaft removed.
Release screws (1 and 3) with special tool 11 4 420.
Tightening torque: 11 12 2AZ
Release screws (2) with special tool 11 8 580 from outside inwards.
Tightening torque: 11 12 1AZ
Important!
All screws must be replaced.
Jointing torque and angle of rotation must be observed without fail (risk of damage).
Secure special tool 11 0 320 with old cylinder head cover bolts (1).
Tightening torque: 11 12 4AZ.
Important!
Weight of cylinder head with add-on parts is approx. 40 kg.
Remove and install cylinder head with two persons.
Do not set cylinder head down on sealing surface, risk of damage to engine valves.
Insert 11 4 430 special tool into bores.
Use special tool 11 4 471 to remove coarse gasket remnants from sealing surfaces on cylinder head and on crankcase.
Important!
Do not use any metal-cutting tools.
Remove fine gasket remnants with special tool 11 4 472.
Important!
Do not use any metal-cutting tools.
There must be no fluids or contaminants in any of the threaded holes (1) for the cylinder head bolt connections.
Risk of corrosion and cracking!
Clean all threaded holes.
Replace cylinder head gasket.
Important!
Observe tightening sequence.
Fit new cylinder head screws.
Insert bolts (1 to 10) with special tool 11 5 190.
Tightening torque: 11 12 1AZ.
Insert bolts (11 to 14) with special tool 11 4 420.
Tightening torque: 11 12 2AZ.
Note:
Graphic shows camshafts removed.
Observe tightening sequence.
Installation:
^ Jointing torque: Screws 1 to 14 / 1x 30 Nm
1) Angle of rotation: Screws 1 to 14 / 1x 90°
2) Angle of rotation: Screws 1 to 10 / 1x 90°
3) Angle of rotation: Screws 1 to 14 / 1x 45°
Replace screws (1).
Tightening torque: 11 12 3AZ.
Important!
Secure screw (2) with a gripper against falling out.
Installation:
Replace aluminum screws.
Assemble engine.
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