Defender (1993+). Manual — part 21

RR1797E

ENGINE

ST813M

REMOVE TIMING

CHAIN SPROCKET

AND

CAMSHAFT

1.

Remove retaining bolt and washer. Withdraw

distributor drive gear and spacer.

Examine components

4. Visually examine all parts for wear. Fit a new

camshaft

if

bearing journals and cams show

signs of wear, pits, scores and overheating.

2. Withdraw sprocket complete with timing chain.

5. Examine links and pins

of

timing chain for

wear. Compare its condition with a new chain.

Inspect teeth

of sprockets,

if

necessary

fit

a

new sprocket.

6. Measure camshaft journals for overall wear,

ovality and taper. Diameters of journals are as
follows, from front of shaft:

Number 1 journal 45,4 to 45,3 mm
Number 2 journal 44,6 to 44,5 mm
Number 3 journal 43,84 to 43,81 mm
Number 4 journal 43,07 to 43,05 mm
Number 5 journal 42.31 to 42,29 mm

7.

To check camshaft for straightness rest two
end journals i.e. numbers

1

and

5

on 'V'

blocks and mount a dial gauge on centre

'journal. Rotate shatt and note reading.

If

run

out

is more than 0.05 mm fit a new camshaft.

3. Withdraw camshaft, taking particular care not

to damage bearings in cylinder block.

ENGINE

ST816M

REMOVE AND OVERHAUL CONNECTING RODS

Overhaul

AND PISTONS

NOTE: Retain connecting rods, caps and bearing

1.

Withdraw retaining bolts and remove sump.

shells

in sets, in correct sequence. Remove

2. Remove sump oil strainer.

piston rings over

crown of piston.

If

same piston

3. Remove connecting rod caps, retain in

is to

be

refitted, mark it relative to its connecting

sequence for reassembly.

rod to

ensure that

original assembly is

4.

Screw

guide

bolts

LRT-12-041

onto

maintained.

connecting rods.

7. Withdraw piston pin, using tool LRT-12-013:

a.

Clamp hexagon body

of LRT-12-013

in vice.

b.

Position large nut flush with end of

centre screw.

C.

Push screw forward until nut contacts

thrust race.

d.

Locate piston adaptor LRT-12-013

with its long spigot inside bore

of

hexagon body.

e.

Fit

remover/replacer bush

of

LRT-12-013 on centre screw with

flanged end away from piston pin.

f.

Screw stopnut about half-way onto
smaller threaded end of centre screw,
leaving a gap 'A' of

3

mm

(1/8

in)

between nut and remover/replacer
bush.

5. Push connecting rod and piston assembly up

g.

Lock stop-nut securely with

lock

cylinder bore, withdraw

it

from top.

Retain

screw.

connecting rod and piston assemblies in

h.

Check that remover/replacer bush is

sequence with respective caps.

correctly positioned in bore of piston.

6.

Remove

guide

bolts

LRT-12-041

from

i.

Push connecting-rod to

right

to

connecting rod.

expose end

of piston pin, which must

be located in end of adaptor 'd'.
Screw large nut up to thrust race.
Hold lock screw and turn large nut
until piston pin has been withdrawn
from piston. Dismantle

tool.

j.

k.

ST777M

Original pistons

9.

Check cylinder bore dimension at right angles
to piston pin

40 to

50 mm from top.

8. Remove carbon deposits, particularly from ring

grooves. Examine pistons for signs

of

damage

or excessive wear, refer to new pistons for
method

of checking running clearance. Fit

new pistons

if

necessary.

New pistons

NOTE: Pistons are available

in

service standard

size pistons supplied 0.0254 mm oversize.
Oversize pistons are

0.25 mm and 0.50 mm

oversize. When fitting new service standard size

pistons t o a cylinder block, check for correct
piston to bore clearance, honing bore

if

necessary. Bottom of piston skirt/bore clearance
should

be 0.018 to 0.033 mm.

NOTE: Piston and cylinder block temperature
must

be same to ensure accurate measurement.

When reboring cylinder block, crankshaft main
bearing caps must

be fitted and tightened to

70

Nm.

ST817M

ENGINE

10.

Check piston dimension at right angles to

14.

Temporarily fit compression rings

to

piston.

piston pin, at bottom

of

skirt.

15.

The ring marked ‘TOP’ must be fitted with

marking uppermost into second groove. The

chrome ring

fits

top groove and can be fitted

16.

Check compression ring clearance in piston
groove. Clearance limits:

0.05

to 0.10 mm.

either way round.

ST818M

11.

The piston dimension must be 0.018 to 0.033
mm smaller than cylinder.

12.

If new piston rings are to be fitted without

reboring, deglaze cylinder walls with a hone
without increasing bore diameter, to provide a

cross-hatch finish. After honing, thoroughly
clean piston bores

to

remove all traces

of

foreign matter.

held square to bore with piston. Gap limits:

0.44

to 0.56 mm. Use a fine-cut flat file to

increase gap

if

required. Select a new piston

ring if gap exceeds limit.

NOTE:

Gapping

does

not apply to

oil

control

rings.

Fit piston rings

13. Check compression ring in applicable cylinder,

17. Fit expander ring into bottom groove making

sure that ends butt and do not overlap.

18.

Fit

two

ring rails to bottom groove, one above

and one below expander ring.

19. Fit second compression ring

with

marking

’TOP’ uppermost. Fit chrome ring into top
groove, either way round.

ST821M

ST819M

19