S46, S56, S66, RB75 +4X4

Phaser Engine Section12A-09

Cylinder head assembly

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To inspect and to correct

Special tool:
Gauge, valve depth, PD.41 D
Dial gauge for use with PD.41 D, PD.208

1 Check the depth of the valves below the face of the cylinder head before the valve springs are removed. Ensure that the heads of the valves and the bottom face of the cylinder head are clean. Put the valve depth tool on the face of the cylinder head and zero the dial gauge.

Carefully put the valve depth tool in position over the head of each valve (A) and make a note of the measurement. In service the maximum depth for the inlet valve is 1,85 mm (0.073 in) and for the exhaust valve it is 2,08 mm (0.082 in).

If a valve is below the depth limit, check the valve depth with a new valve in position. If the valve depth is still below the limit and a valve seat insert is fitted, the insert must be renewed.

Where a valve seat insert is not fitted, the bottom face of the cylinder head can be machined to reduce the valve depth, or an insert can be fitted, operation 12A-14.

2 Check the valves for cracks. Check the stems of the valves for wear and for correct fit in their valve guides.

3 Check that the seat faces of the valves are not badly burnt or damaged. Seat faces of valves which are damaged can be ground on a special machine. Valves which have only little damage can be lapped to their valve seats. When new valves are fitted, the valve depths must be checked, see paragraph 1.

4 Check that the load on the valve springs is correct at their fitted length, see section 11 C.
Fit new valve springs at every complete engine overhaul.

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