R&R and Inspection of Cylinder Head
Disconnect coolant hose at coolant pipe.
Remove sensor.
Installation:
Replace sealing ring.
Remove thermostat housing and thermostat.
Installation:
Vent points up.
Replace O-ring.
Coat O-ring lightly with glycerin.
(1) O-ring
(2) Seal
Unscrew upper timing-case cover.
Installation:
Apply flexible sealing compound 3 Bond 1209 thinly and evenly to the groove ends.
Installation:
Replace seals.
Installation:
Position timing-case cover and secure with 2 bolts.
Do not damage sealing surface.
Press timing-case cover downward until upper edge of timing-case cover and cylinder head are on the same plane.
Screw in and tighten all bolts.
Tightening torque:
M6 screw = 10 Nm
M7 screw = 15 Nm
M8 screw = 22 Nm
M10 screw = 47 Nm
Rotate engine in direction of rotation until cams tips on intake and exhaust cams of cylinder 1 face one another.
Arrows on sprockets face up.
Installation:
Secure crankshaft in TDC position with special tool 11 2 300.
CAUTION! Remove special tool prior to operating engine.
Installation:
Align camshafts and secure with special tool 11 3 240.
CAUTION! Make sure that bearing banks are not damaged.
If necessary, machine open-end wrench accordingly.
CAUTION! If the camshaft setting must be corrected so far that a valve movement takes place on the 1st and 4th cylinder, turn back the crankshaft approx. 45 °C and do not turn back again until after the camshaft turns.
This prevents contact between valves and pistons.
Unfasten screw plug and remove hydraulic chain tensioner.
CAUTION! If the seal plug of the hydraulic chain tensioner is released, the hydraulic piston extends and is locked against compression with a detent ring. Installation of the hydraulic chain tensioner in extended (locked) position leads to engine damage.
Always follow installation instructions. Timing Chain Tensioner
Unscrew upper chain guide.
Unscrew upper chain guide bolt on right-hand side.
Unscrew chain wheels.
Installation:
Arrows on chain wheels face up.
Tightening torque: M6 screw = 10 Nm
NOTE: Use special tool 11 2 250.
Unfasten cylinder-head bolt in several passes in the sequence 10 ... 1.
Remove cylinder head and cylinder-head seal.
NOTE: Standard-production cylinder heads have punch-locked washers to avoid losing them.
When installing a new cylinder head, fit new washers without peening.
Installation:
Clean sealing surfaces of cylinder head and engine block. Remove gasket residues with hardwood spatula while making sure that no gasket residues fall into the oil and cooling passages.
Lay on new cylinder-head gasket with identification "TOP" facing upward and "FRONT" on the chain end. Check dowel sleeves (1) for damage and correct installation position.
NOTE: In contradiction to the M40 engine, a reactor for supply of oil to the cylinder head is not installed in the M42 engine block.
CAUTION! A check valve with rubber-lined spacing sleeve for supply of oil to the cylinder head is installed in the engine block of M42 engines produced since 9.92.
Installation:
Install check valve (1) in the oil supply passage for the cylinder head with the collar facing the engine block.
Insert rubber-coated spacing sleeve (2).
CAUTION! If check valve (1) is installed in the wrong direction, it will block the supply of oil to the cylinder head.
Installation:
For machined (flattened) cylinder heads a 0.3 mm thicker cylinder-head gasket is available.
Installation:
Lay new seal in the timing case.
NOTE: The seal can also be used for the thicker cylinder-head gasket.
CAUTION! Cylinder-head bolts must only be used once.
Keep oil out of tapped bores in the engine block (danger of cracking the block, incorrect tightening torque values).
Position cylinder head and install new cylinder-head bolts (lightly oiled).
NOTE: Use special tool 00 9 120 or special tool 11 2 110 for torsion angle tightening.
Installation:
Tighten down the cylinder-head bolts in order 1 ... 10.
Tightening torque: M10 screw
Jointing torque = 30 Nm
Torque angle = 90°
Torque angle = 90°