12
10
Clean the face
of
the cylinder head and
remove all traces
of
carbon and any high spots.
11
Clean
out
tb_e
water ways.
If
deposits exist on the piston crowns
proceed
as
follows:
(a) Turn
the
crankshaft until the Nos. 1 and 4
pistons are at TDC.
(b)
Fill the Nos. 2 and 3 cylinder liner botes
with
clean
non-fluffy
rag
to
prevent carbon
falling into the bores, and cover the cam
follower
apertures.
(c) Carefully,
without
scoring the piston
crown, remove the carbon deposits leaving a
band
of
carbon approximately
3·1
mm
(iin)
wide
around
the
periphery
of
the piston crown,
on No. 1 piston. Avoid carbon particles
falling
into the cylinder block water ways. Repeat for
No. 4 piston.
(d)
Turn
the
crankshaft
to
enable pistons 2
and 3
to
be cleaned.
To
replace
1 Clean
th~
cylinder block face, removing all
traces
of
carbon and any high spots.
2 Replace valve guides in cylinder head
using tool No.
RT
7478 {see Figure 14).
3 Lap,.in the valves using fine grinding paste
until a gas-tight
joint
is obtained. Ensure
valves
are
replaced in original positions and
that
no
grinding paste particles remain.
4
lubricate
the valve stems
with
clean
engine oil and assemble
to
the cylinder head.
Ensure that valve spring collars and split cotters
are correctly seated. Renew valve stem
oil seals.
·
Refit the cylinder head, using a
new
cylinder
he~d
gasket.
Operation
11
- Pistons, connecting
rods and bearing
replacement
(with
cylinder head and sump removed)
To
remove
1 Remove oil pump assembly (see
Operation
4).
2 Turn the crankshaft
to
bring numbers 1
and 4 connecting rod
bolts,to
an
accessible
' . . \
~
pOSitiOn.
3 Check the identifying marks on the
connecting rods and bearing caps. Mark
if
necessary.
4 Release the locking plates, unscrew the
bolts and remove
the
big end bearing caps,
complete
with
the lower half bearing shells.
The engine
5 Push the connecting rods and pistons
upwards and carefully withdraw, identifying
for reassembly.
6 Match
up
the
top
and bottom bearing
shells and caps
with
their respective
connecting rods and piston assemblies.
Overhaul
1 Immerse piston and con rod assemblies in
hot
water
for
a
few
minutes, then release the
gudgeon pin retaining circlips.
2 Using a suitable drift remove the gudgeon
pins and disconnect the con rods from the
oistons.
3 Check the
small end bushes for wear and,
if
necessary, renew using a suitable hand press
to
remove the old bushes and
fit
new. Ensure
that the oil hole in the bush corresponds
with
the hole in the connecting rod.
4 Having pressed in
new
small end bushes,
check that they
will
accept new gudgeon pins,
for
it
may be necessary
to
ream
out
the bushes
with
an expanding reamer until a
tight
push
fit
is
obtained.
Note:
It
is
im~rtant
during this operation
that the bush is reamed squarely
to
the con
rod
to
ensure correct alignment.
5 Remove the piston rings
with
an
expander
tool and clean.
6 Clean the pistons, removing all carbon
deposits, particularly from the piston ring
grooves.
7 Assemble pistons
to
the connecting rods,
securing in position
with
the gudgeon pins
and circlips.
It
may be necessary
to
heat the
pistons in hot water
to
facilitate the operation.
Note:
Engines up
to
No.
5J/85/25866
have
angled con rods
which
must be assembled
with
cutaway angle on camshaft side.
8 Before fitting the piston rings, position the
rings in their appropriate liners for gapping,
which
should be
0·17-0·30mm
(0·007-
0·012in).
9 Fit the piston rings, fitting the scraper ring
in the lower piston groove,
followed by the
taper compression ring.
Note:
The
'top'
mark
Qn
the taper compression
ring must
face uppermost. The upper groove in
the piston accommodates the plain
compress1on ring.
10
Insert the piston and connecting rod
assemblies into the appropriate bores,
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