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Page Hl
CYLINDER
HEAO
The Diesel engine rarely, if ever, needs the
periodical decarbonising that is accepted as a
matter of course with the petrol engine, insofar
that in an engine operating on the diesel cycle,
carbon, beyond a superficial coating, does not
fonn and accumulate in the combustion chamber
and on the pistons as in the case of the petrol
engine.
O~ing to its higher therm al efficiency, the valves
of the Diesel engine are also much more free from
trouble due to overheating; that is, of course,
providing the engine is reasonably maintained.
Af ter aperiod, depending upon the condition~
under which the engine is operated, the valves
may need attention. This will become apparent
by loss of compression, in which case a top over-
haul may be necessary.
Remove push rods.
Remove leak off pipes to atomisers.
Remove pressure pipes to atomisers.
Remove atomisers.
Remove main leak off pipe.
Uncouple union on pipe connecting the venturi
and the pneuma tic governor (where fitted).
Take off cylinder head Duts and remove cylinder
head complete with exhaust manifold and venturi.
To Remove Valves.
All valves are numbered consecutively from I
to 8, commencing from the front of the engine.
The cylinder head is marked with corresponding
numbers opposite the valve seats, see Fig. H.2.
Compress the spring cap and springs with a
valve spring compressor and remove the split-cone
collets. Remove the spring caps and springs,
thus liberating the valve which can be taken
out when the cylinder head is turned upside
down.
Grinding Valves.
The valves and valve seats should be recon-
ditioned in the orthodox way, using grinding
compound or by means of specialised equipment.
The valve seat and face angle is 45°,
Preparation.
Begin by assembling all the joints and other
parts required, as called for in the Perkins parts
List.
Drain all water from the radiator and cylinder
block. The drain cock for the cylinder block is
on the fuel pump side of the engine. Disconnec
the exhaust pipe from the engine exhaust manifold t
Uncouple extemal connections to the cylinder head.
(J'
EXA1\IUN A nON.
Examine all parts for wear, having in mind tbe
following points:-
Cylinder Head. To Remove.
Remove the air cleaner.
Take oir cylinder head cover.
Uncouple union on oil pipe to rocker assembly.
Remove Duts holding rocker shaft assembly.
Remove retaining plates and lift oir rocker
assembly, bringing above named oil pipe with it.
Valve Springs.
Valve springs deteriorate because of fatigue
resulting from the combined effect of heat and the
normal working of the springs. . Af ter aperiod
Fig. Hl
Showing Rocker Shaft Assembly
J.
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