MG MGB User Manual

THE
ENGINE
Oil
pressure
relief
valve
The
automatic
relief
valve
in
the
lubrication
system
deals
with
any
excessive
oil
pressure
when
starting
from
cold.
When hot,
the
pressure
drops
as
the
oil becomes
more
■uid.
Should the
oil
■lter
become
blocked,
two
relief
valves
in
the
■lter
blow [off
to
enable the
oil
to
by-pass
the ■lter
and
pass
direct
into
the
main
gallery.
Continuous
cold-running
and
unnecessary
use
of
the
mixture
control
are
often the
causes
of
serious
oil dilution
by
fuel,
with
a
consequent
drop
in
pressure.
Particular
attention
is
called
to
the
recommended
changes
of
oil.
The
non-adjustable
oil
pressure
relief
valve
is
situated
at
the
rear
of the left-hand
side of the
cylinder
block and
is
held
in
position
by
a
domed
hexagon
nut
sealed by
two
fibre
washers
or one
copper
washer.
The relief
valve
spring
maintains
a
valve
cup
against
a
seating
machined
in
the
block.
The
valve
should
be
examined
to
ensure
that the
cup
is
seating
correctly
and that
the relief
spring
has
not
lost
its
tension.
The
latter
can
be checked
by
measuring
the
length
of
the
spring
to
give
the
correct
relief
pressure
(see
‘GENERAL DATA’).
Fit
a
new
cup
and
spring
if
necessary.
Section
A.3
WATER PUMP
The
water
pump
is
of
the centrifugal
impeller
type
and
is
mounted
on
a common
spindle with
the fan
in
a
casting
bolted
to
the front
of the
cylinder
block.
The
water
pump
and fan
assembly
is
attached
to
the front
of
the
cylinder
block
by
four
bolts and
may
be withdrawn
and
serviced
as
detailed
in Section C .7.
If the
gasket
is
damaged
as
the
pump
body
is
withdrawn
from
the cylinder
block,
ensure
that
all
traces
of
itare
removed before
a
new
gasket
is
■tted
and the
pump
replaced.
Section A.4
MAN
IF OLDS
Remove
the
air
cleaners
and carburetters
as
detailed
in
Section
D.
Disconnect
the distributor
vacuum
pipe and,
on
early
cars,
the heater
pipe
from
the
manifold.
a
Remove
the
six
exhaust
pipe
to
manifold
clamp
bolts
and
‘
spring washers
and release the
pipe.
Six
studs
and
nuts
secure
the
manifolds
to
the
cylinder
head.
The four
centre
nuts
have
large
washers,
enabling
them
to
secure
both
the
inlet
and
exhaust
manifolds.
The
two
remaining
nuts,
one
at
each
end of
the
manifolds,
have
small
washers
and
secure
the
exhaust
manifold
only.
Replacements
of
the
manifolds
is
a
reversal
of
these
instructions.
Use
a new
gasket.
Section
A.5
“
ROCKER
ASSEMBLY
b
Drain
the
cooling
system—Section C
.4.
Disconnect
the
breather
pipe
from
the
rocker
cover, on
18GB
and
18GF
engines,
unscrew
the
nuts
securing
the
heater
pipe
to
the
rocker studs
and
move
the
pipe
clear
of
the
rocker
cover.
Release
the breather
pipe
from
the
front
of
the
rocker
cover.
Withdraw
the
throttle
cable from
the
lever
and
outer
cable
abutment.
Unscrew
the
two
nuts
and lift
off the
rocker
cover,
taking
care
not
to
damage
the
cork
gasket
or
lose
the
washers
and rubber
seals. Notice
that
under the
right-hand
rear
rocker
stud
nut
is
a
special locking
plate.
Unscrew
the
eight
rocker shaft
bracket fixing
nuts
gradually,
a
turn
at
a
time,
in
the
order shown
in
Fig.
A.2
until
all
load has
been»
released.
It- is
necessary
to
drain
the
radiator
and slacken
the
seven
external cylinder
head
securing
nuts
because
four
of
the
rocker
shaft
bracket
fixing
nuts
also
secure
the
cylinder
head,
and if
the
seven
external
cylinder
head
fixing
nuts
are
not
slackened
distortion
may
result
and
water
find
its
way
from
the
cooling
system
into the
cylinders
and
sump.
W
3W2
I
1W1
W
l
y
it
t
\
I
/
4'
“mm
M
.
a
"lit
"
w!‘
H‘hi‘lw‘t
Fig.
A.1
Fitting
a
valve
rocker bush,
usingService
tool 186
226
MGB.
Issue
7.
80619

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English