Valve Cover: Description and Operation

CYLINDER HEAD COVER VERSIONS
Mercedes has 4 versions of the cylinder head cover for the 102 SOHC engine. Later versions of the cylinder head cover can be used on the earlier engines. The following will help determine which version is on the engine.

FIRST VERSION:
The cylinder head cover is manufactured from a magnesium alloy and is coated on the outside with a black colored plastic.





A two-part. glass fibre reinforced polyamide rectangular tube (107) in which the ignition cables run is inserted in a longitudinal groove of the cylinder head cover. In addition, the ignition cables and the vent line at the face end of the cylinder head cover run through a plastic holder (arrow).





On the inside, the oil separator (109) and the related outlet pipe are fixed in place with the hose piece (arrow) of the crankcase ventilation.





The spacer sleeves (arrows) prevent the gasket being squeezed when tightened.

SECOND VERSION:
In January 1986 a cylinder head cover made of plastic was fitted (on engines without pressure oil pump for level control).





Distinguishing features:
^ Collar bolt (151)
^ Hose connection for crankcase ventilation with larger OD.





The cylinder head cover gasket has wider plates (arrows) for sealing the bolt guides.

NOTE If the cylinder head cover has to be replaced, e. g. because of cracking, install the previous magnesium cylinder head cover.

THIRD VERSION:





As of February/March 1985 the oil separator is installed in the cylinder head cover with a vent pipe (arrow).

FORTH VERSION:









Since 12/88 a cylinder head cover has been installed which has a recessed wall (arrows) in the area of the spark plug recesses.
This prevents the valve spring or the valve spring plate rubbing the cylinder head cover and causing noises.
The modified cylinder head cover can also be installed on previous engines in the event of complaints.