A
LUBRICATION
SYSTEM
SECTION
AS
OIL
PRESSURE
The
011
pressure
Is
controlled
by
means
of
the
relief valve situated at
the
rear
of
the
centre
crankcase,
on
the
left side (Fig.
AS).
When
the
engine
ii
stationary
there
will be no oil
pressure.
On
starting
from cold,
pressure
may
be
as high
as
90 Ibs., p.s.l. temporarily, reducing, when hot,
to
thenormal
running figure
of
75/90 Ibs. p.s.l.
at
three
thousand
r.p.m.
Fig. AS.
The
oil
pressure
reller
valve
The
pressure
can
only be checked with a gauge
connected
to
an
adaptor specially designed
to
replace
one
of
the
blanking plugs on
the
front
of
the
centre
crankcase (see
Fig.
B34).
If
satisfactory readings are not obtained, check
the
followlng:-
(1)
That
the
oil pressure relief valve gauge
is
clean.
(2)
That
the
oil level
Is
not
below
the
minimum
mark on
the
dipstick, and
that
oil
is
being
returned
to
the
tank.
(3)
That
the
sump filter, crankcase filter,
and
tank
filter are clean and not blocked.
(4)
That
the
oil
pump
is
functioning
properly,
and
that
there
is
a supply
of
oil
to
the
pump.
Refer
to
Section
A7
for checking
the
oil pump.
(S)
That
the
drillings
In
the
crankcase connecting
the
011
pipes
to
the
oil
pump are clear.
(6)
That
the
big ends and
centre
plain main bearings
are
not
excessively worn.
If
the
bearings have
too
great a working clearance, oil will escape
more readily, particularly when
warm,
thus
giving a reduced pressure.
Excessive periods
of
slow running (such as in heavy
traffic), or unnecessary use
of
the
air
control,
can
cause dilution
of
the
oil, and hence
an
overall
drop
In
pressure, due
to
the
lower viscosity
of
the
diluted
oil.
Most lubrication and
oil
pressure
troubles
can be
avoided
by
regular attention
to
the
recommended
oil changes.
SECTION
A6
THE
OIL
PRESSURE RELIEF VALVE
The
oil pressure relief valve
Is
very reliable and
should
reqUire
no
maintenance
other
than cleaning
of
the
gauze. It
Is
situated on
the
underside
of
the
engine
to
the
rear of
the
oil pump housing. Oil
pressure
Is
governed
by
the
single
spring
situated
within
the
valve body, and if It
Is
suspected
that
the
spring
Is
faulty, then
the
valve must be replaced
as
a
unit.
A8
The
spring strength
Is
designed
to
operate
the
valve
at
a pressure
of
7S·8S lb.
psi.
with
the
oil
at
normal running temperature.
Unless a special tool
is
available, access
to
the
relief
valve assembly
can
only be
obtained
by
stripping
the
primary transmission (Section
C).
Service tool 60·2135
can
be obtained
to
remove
the
relief valve after
the
fiexible oil feed and scavenge
pipes have been disconnected
at
the
crankcase.
To Next Page
Loading...
