24
Design and function
Component description
Cylinder heads
The engine has two (identical) cylinder heads, each of
which covers three cylinders. The cylinder heads are
screwed to the cylinder block by 20 screws per head
(M11).
The cylinder head material is a special cast iron alloy.
The cylinder head gasket is solid sheet steel.
The cylinder head plane has lands, formed by two
concentric wide grooves, recessed in the plane of the
cylinder head, centred on the cylinder liner collars.
These grooves determine the size of the sealing sur-
face so that the requisite sealing pressure is obtained
without the tightening torque needing to be so high
that there is a risk of deformation of the liner shelf in
the cylinder block. In addition, there is a groove for
the “flame edge” of the cylinder liner.
The fastening screws for the cylinder head are tight-
ened by means of a combination of torque and angle
tightening.
Valve mechanism
The valves are made from chrome nickel steel, the
valve stems are chrome plated. The exhaust valves
for TAMD71/72 and the inlet valves for TAMD63 (from
Autumn 1995) have valve heads made from Nimonic
80. The exhaust valves on other engines of the 6(x)
series have Stellite coated sealing surfaces. The
valves are operated by rockers on a rocker bridge.
The engine has two rocker bridges, one for each cylin-
der head. The rockers are operated by the camshaft,
via push rods and valve lifters.
Depending on the design of the cylinder head (valve
seat location), there are two different valve heights on
the 6(x) series. The illustration and table show the dif-
ference between the location of the valves (valve
height above cylinder head plane).
The valve seats made from special steel are inter-
changeable. Valve seats with standard dimensions
and overdimensions are available as spare parts. The
overdimension seat has a 0.2 mm greater overall di-
ameter and is used if the cylinder head needs the
valve seat locations to be milled out.
Cylinder head sealing
1 Cylinder head 3 Cylinder liner
2 Cylinder block 4 Cylinder head gasket
14
3
2
Valve location
A = Inlet
B = Exhaust
AB
TAMD62 0.7–1.1 0.7–1.1
TAMD63 0.0–0.4 0.0–0.4
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