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Page PI
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CP)
SYSTEM
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Note :-Lubricating Gil SpeciJications in Appendix
Tbe importance of correct and clean lubrication
cannot be stressed toa highly and all references to
engine oil should be taken to mean lubricating oil
which raIls within the specifications given in the
Appendix. Care should be taken that the oil
chosen is that specified for the climatic conditions
undcr which the engine is operated.
Tbe sump should be filled with suitable lubri-
I."ant to the correct level, but do not attempt to
overfill above the ruIl mark. Before filling, or
checking the dipstick. ensure that the engine is
level.
,
are in line with the feed from the centre main
be.\ring, oil flows to the top face of the cylinder
block. Since these drillings coincide but mom en-
tarily for every revolution of the camshaft, only a
reduced quantity of oil is delivered to the drilling
leading to the top t:'lce of the cylinder block.
This drilling matches up with a vertical passage
machined through to the top face of the cylinder
head from whence the oil is taken by an external
pipe to the hollow rocker shaft. Drillings in th is
shaft allow the oil to pass to the rockers, the over-
flow being returned to the sump by way of the
push rod chamber.
Gil also flows from the front main hearing
bracket via a hole drilled in the front of the cylinder
block to the idler gear spigot from which it escapes
through a drilling in the boss of the idler gear
to lubricate the timing gears.
A further drilling from No. I Main Bearing
Housing conveys oil to the front camshaft hearing,
surplus oil returning to the sump.
Oil Pressure.
Sec tbat oil pressure is registered on the gauge.
The actual pressure may vary with individua!
engines and under different operating conditions
but shou!d he 25/50 Ibs. per sq.in. (1.76/3.52 kg/
sq.cm) at working temperature and maximum
engine speed.
Ir the oil pressure, as registered on the gauge, is
below normal check the following in tbe order
gJven below.
(I)
Dipstick. Ensure that there is sufficient oi!
in the sump.
(2) Oil pressure gauge. Check for accuracy
with master gauge.
(3) Lubricating oil filter. May be choked. clean
or re-ncw element (see periodical attentions Section
F).
(4) Sump strainer. This may be choked, remove,
clean and replace (for removal instructions sec
Page P.2).
(5) Lubricating oil pump. Ensure that suction
and delivery pipe uni ons are tight.
(6) Oil pressure relief valve. Foreign matter
may be preventing the valve from closing. For
cleaning ifistructions Page P .3.
Gil Circulation.
Tbe system of lubrit:ation is pressure reed to
main and big end beanngs, to camstlaft bearings
and to vaJve rocker assembly.
The pump draws oil through the strainer from
the sump and delivers it by an extern al pipe
inside tbe crankcase througb a drilling in tbe side
of tbe cylinder block ; thence through the lubri-
cating oil filter bracket to the lubricating oil filter.
From the tilter it is delivered througb a second
drilling in the lubricating oil filter bracket and
cylinder block to the pressure rail wbich is an
internal passage witbin the crankcase; holes are
drilled which lead from the pressure rail to tbe
crankshaft main hearings and holes dril led in tbe
cranksbaft carry oil to the big end bearings.
Surplus oil returns to the sump.
A seal prevents oil leaking from the rear end
of the crankshaft.
The smalt end bushes are lubricated by splash
and lubricating oil mist.
A passage from tbe centre main bearing conveys
oil to tbe centre camshaft hearing which is also
in open communication with the top face of the
cylinder block by means of a vertical drilling.
In conjunction with tbe centre camshaft journal,
this Jatter drilling serves to provide oil at a teduced
pressure to tbe top face of tbe cylinder block and
thence to the rocker assembly.
The camshaft journal contains two drilled
passages and when, as in Fig. P.2, these drillings
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