SECTION L
Lubricating System
The importance of correct and clean lubrication
cannot be stressed too highly and all references to
engine oil should be taken to mean lubricating oil which
falls within the specification given in the appendix. Care
should be taken that the oil chosen is that specified for
the climatic conditions under which the engine is
operated.
The sump should be filled with a suitable grade of
lubricant to the correct level but do not overfill above the
full mark.
Description
The lubrication is of the forced feed type, the oil
being circulated, under pressure, by a lobed rotor type
oil pump which is mounted on the front main bearing cap
and driven through an idler gear by the crankshaft gear.
The oil is drawn through a sump strainer and a suction
pipe before entering the pump itself. Oil is then pumped
via a pipe to the relief valve housing and then through an
internal drilling in the cylinder block to an externally
mounted adaptor onto which is fitted the full flow type
lubricating oil filter. This adaptor channels the oil first to
and from the oil cooler section of the heat exchanger, by
means of flexible pipes, then through this full flow
lubricating oil filter back into the cylinder block. The oil
passes via drillings within the cylinder block to the
pressure rail (main oil gallery).
With lowline engines, the oil cooler and lubricating
oil filter are an integral component fitted on the starboard
side of the engine.
From the pressure rail the oil is fed through oilways
in the crankcase webs to the five main bearings and
then from these through oilways drilled in the crankshaft
webs the oil passes to the big ends. An oil seal prevents
oil leaking along the crankshaft at the rear end and oil
thrown from this seal returns to the sump.
The three camshaft bearings are lubricated through
oilways in the crankcase webs from numbers one, three
and five main bearings.
The camshaft centre bearing supplies a controlled
feed of oil through an oilway, in the cylinder block and
cylinder head, to the rocker shaft assembly. This
controlled feed is achieved by allowing oil under
pressure to be forced to the rocker shaft only when the
oilways in the camshaft journal and camshaft centre
bearing are in line, this occurring once per camshaft
revolution. Oil from the rocker shaft escapes through a
small bleed hole in each rocker lever and lubricates the
valves and guides by splash, the surplus oil being
returned to the sump by gravity.
The idler gear and hub are pressure lubricated direct
from the pressure rail. Oil enters the rear of the hub and
passes through drillings in the hub to lubricate the idler
gear bush and gear retaining plate. Timing gear teeth
are splash lubricated by surplus oil from the front
camshaft bearing idler gear hub and fuel pump hub.
Pistons, cylinder liners and connecting rod small end
bearings are lubricated by splash and oil mist, also the
cams and tappets of the valve mechanism.
THE OIL PUMP
The oil pump is secured to the front main bearing
cap by three setscrews, a protrusion of the idler gear
shaft locating in a hole in the bearing cap to give positive
location.
The bushed idler gear which is free to rotate on its
shaft transmits the drive from the crankshaft gear to the
oil pump gear.
The oil pump drive gear is pressed and keyed on to
the pump driven shaft on the other end of which is
pressed and pinned a three lobed rotor. This rotor
meshes with a four lobed driven rotor, which is free to
rotate in the cast iron pump body.
