M20 engine
Withdrawal
Unscrew base plate F.
Disconnect ventilation hose -arrow-.
Unscrew 8 bolts and nuts and remove the cylinder head cover.
Installation
Check the integrity of the cylinder head cover gasket and replace if necessary.
Place cylinder head cover on cylinder head and tighten slightly.
Tighten nuts and bolts in sequence from 1 to 8 to 9 Nm.
Warm up the engine and check the tightness of the cylinder head cover.
M21 engine
Withdrawal
Remove the air hose between the air filter and the turbocharger by first loosening and pulling back the clamps.
See drawing W - 1095
Disconnect the hydraulic brake booster hose from fitting 8.
Loosen the three bolts of the toothed belt cover without unscrewing,
See drawing W - 1096
Remove air hose 7 after loosening clamp 8.
Disconnect hose 9 from oil separator 1 after loosening clamp 10.
Unscrew bolts 3/4 of oil separator 1.
Loosen the 4 cap screws and remove the cylinder head cover.
1 cylinder head cover
2 Cork
3 Gasket
4 O-ring
5 O-ring
6 Head bolt
7 Heat shield
8 Vacuum pump
1 Oil separator
2 O-ring
3, 4 Bolts
5 Hose
6, 8, 10 Clamps
7 Air hose
8 hose
Installation
Check the integrity and absence of cracking of the cover gasket and rubber ring 4 (See fig. W-1095) and, if required, replace.
Insert and lubricate the rubber ring with engine oil.
Install cover gasket, install cylinder head cover.
Insert threaded bushings with new sealing rings and tighten crosswise to 15 Nm.
Check oil separator O-ring, replace if necessary. Install the oil separator.
Tighten the toothed belt guard bolts.
Attention: First tighten the cylinder head cover and then the toothed belt guard.
Put on the hoses and secure them with clamps.
M30 engine
Withdrawal
Pull the idle air regulator out of the air intake hose. First disconnect the connector and unscrew the coupling nut.
Disconnect the air mass meter connector.
Loosen the air intake hose clamps. Remove the 3 retaining clips from the underside of the air mass meter. Remove the air hose with an air mass meter, while disconnecting the crankcase ventilation hose.
Remove the ignition wires from the coil and from the spark plugs.
Disconnect the ignition distributor cover.
Unbolt the ignition harness and set it aside.
Screw in 8 nuts and 1 bolt from the front of the cylinder head cover distributor and remove the cover.
Installation
Check gasket integrity.
Tightening torque 10 Nm, tighten bolt last.
M50 engine
Withdrawal
Remove the casing and disconnect the connectors of the ignition coils, while folding the metal brackets up.
Unbolt the ignition coils from the cylinder head and remove.
Unscrew the cylinder head cover.
Attention: Pay attention to the location of the rubber pads under the bolts for subsequent installation.
Installation
Replace damaged gaskets. When applying the gasket, pay particular attention to the correct location of the cutouts in the front of the cylinder head
Subsequent installation is carried out in reverse order. Tighten ignition coil and cylinder head cover bolts evenly to 10 Nm.
Connect the ignition coil connectors and secure with metal brackets.