Processing of cylinder head for installation of valve guide bushings (Mercedes-Benz Vito W639)

When replacing valve guide bushings, machining of the holes is performed with the camshaft housing installed. In this case, the base surface for processing is the cylindrical surface of the holes for the hydraulic gap compensators.

The processing is carried out using a special tool.

Note: Heating the cylinder head or cooling the valve guides for installation is not necessary. The use of valve guides with a snap ring was discontinued in November 1994.

After installing the bushings in the cylinder head, perform final processing of the holes in the bushings.

Control dimensions of valve guide bushings

Tightening torques for threaded connections

Screw for fastening the timing gear cover to the cylinder head M8	20 Nm
Screw securing the front cover to the cylinder head	14 Nm
Cylinder head to block mounting screw, stage 1	60 Nm
Cylinder head to block mounting screw, stage 2	90
Cylinder head to block mounting screw, stage 3	90
Flange connection of the exhaust manifold to the turbocharger	30 Nm
Oil line to turbocharger mounting bolt	18 Nm
Bolt for fastening the oil pipe to the cylinder head	9 Nm