Defender (1993+). Manual — part 37

COOLING SYSTEM FAULT DIAGNOSIS

SYMPTOM

POSSIBLE

CAUSE

CURE

A-EXTERNAL LEAKAGE 1.Loose

hose

clips

1.Tighten

2Defective rubber hose

2.Renew

3. Damaged radiator seams

3. Rectify

4. Excessive wear in the water pump 4. Renew

5. Loose

core plugs

5. Renew

6. Damaged gaskets

6. Renew

7. Leaks at the heater connections

7. Rectify

or plugs
8. Leak

at

the water temperature

8. Tighten

gauge plug

1. Defective cylinder head gasket

2. Cracked cylinder wall
3. Loose cylinder head bolts

1. Boiling

2. Internal or external leakage
3. Restricted radiator or inoperative

B-INTERNAL LEAKAGE

1. Renew. Check engine

oil

for

contamination

and refill as necessary
2. Renew cylinder block
3. Tighten. Check engine for

oil

contamination

and refill as necessary

1. Ascertain

the cause

of engine overheating

and correct as necessary
2. See items A and B
3. Flush radiator or renew the thermostat as
necessary

1. See

item D

2. Refill
3. Use air pressure from engine side of the
radiator and thoroughly clean matrix

C-WATER LOSS

F-OVERHEATING

1. Poor circulation

2. Dirty oil and sludge in engine
3. Radiator fins choked with chaff,
mud, etc
4. lncorrect ignition timing

4. Check using electronic equipment

5. Insufficient coolant

5. See item D

6. Low

oil level

6. Replenish

7. Tight engine

7. New engines are very tight and moderate
speeds should be maintained for the first

1,000

miles

8. Choked or damaged exhaust pipe 8. Rectify or renew silencer
or silencer
9. Dragging brakes

9. Adjust brakes

10. Overloading

vehicle

10.

ln the hands

of the operator

11. Driving

in heavy sand or mud

12. Engine labouring

on gradients

13. Low gear work
14. Excessive engine idling

16. Defective thermostat

16. Renew

11. In the hands of the operator
12.

In the hands of the operator

13.ln the hands of the operator
14.

In the hands of the operator

15. lnaccurate temperature gauge

15. Renew

I

D -P O O R CIRCULATION

1. Restriction

in system

1. Check

hoses for crimps, reverse-flush the

2. lnsufficient coolant

2. Replenish

I

3. lnoperative water pump

3. Renew

4. Loose fan belt

4. Adjust

5. Inoperative thermostat

5.Renew

radiator, and clear the system

of rust and

sludge

SYMPTOM

POSSIBLE

CAUSE

CURE

E-CORROSION

1. Excessive

impurity in the water

1. Use

only

soft, clean water together

with

correct anti-freeze or inhibitor mixture

2.

lnfrequent flushing and draining of 2. The cooling system should

be

drained and

system

flushed thoroughly at least once a year

3.

lncorrect anti-freeze mixtures

3.

Certain anti-freeze solutions have a

corrosive effect

on parts of the cooling

system. Only recommended solutions should
be

used.

G-OVERCOOLING

1. Defective thermostat

1. Renew

2. Inaccurate temperature gauge

2.Renew

MANIFOLDS AND EXHAUST

EXHAUST SYSTEM COMPLETE

ST3420M

NOTE: Ensure no exhaust leaks are evident in

either a new or old exhaust system, as this

will

affect vehicle performance.

disconnect any components until exhaust system

WARNING: To prevent personal injury occurring
from

a hot exhaust system,

DO

NOT attempt to

has cooled down.

MANIFOLDS

AND EXHAUST

EXHAUST SYSTEM

EXHAUST MANIFOLD

Remove and refit

Removing

Left hand

Remove and refit

1.

Raise the vehicle on a suitable hoist and

Right hand

apply the parking brake.

2.

Disconnect the electrical plugs from the

Removing

heated oxygen sensors.

3.

Remove the three nuts securing each front

pipe

to

the manifold. and remove the gaskets.

4.

Remove the two nuts and bolts securing the

front pipe to the intermediate pipe.

5.

Withdraw the front pipes with catalysts.

3. Remove the manifold(s) and old gaskets.

6. Remove the two nuts and bolts securing the

intermediate pipe to the tail pipe.

7.

Remove the nut and bolt securing the tail pipe

mounting bracket. Withdraw the tail pipe and
silencer, and collect the rubber mounting.

8.

Remove

the

nut

and

bolt

securing

intermediate pipe front and rear mountings.
Withdraw the intermediate pipe and silencer

and collect the rubber mountings.

1.

Disconnect the front exhaust pipe(s) from the

2.

Tap back the bolt locking tabs and remove the

eight bolts, lock tabs and washers.

Refitting

NOTE: Apply Firegum Putty, part no.

15608

to all

exhaust system joints with the exception of the
exhaust flange to manifold flange, where a new

gasket should be fitted.

9. Reverse the removal instructions.

Refitting

4.

Ensure that the mating surfaces

of

the

cylinder head and exhaust manifold are clean
and smooth.

5.

Coat the threads of each bolt with anti-seize
compound.

6. Place the manifold and new gaskets in

position on the cylinder head and fit the
securing bolts, new lockplates and plain
washers. The plain washers are

fitted

between

the manifold and lockplates.

7.

Evenly tighten the manifold bolts to the correct

torque, see torque wrench settings section 06,
and bend over the lockplate tabs.

8.

Reconnect the front exhaust pipe, using new

exhaust flange gaskets.

INTAKE MANIFOLD

The removal and refit

of

the intake manifold

is

incorporated

in

the Fuel Injection System, Section

19.

manifold(s).