Defender (1993+). Manual — part 17

4

ENGINE

ENGINE FAULT DIAGNOSIS

ENGINE OIL PRESSURE TEST

Service tools:
LRT-12-052: Pressure test equipment

WARNING: Use suitable exhaust extraction
equipment,

if

test

is being carried out in

NOTE: Excessive lubrication pressure can effect
engine performance by over-pressurising the
hydraulic tappets causing the valves to be held
open, see Lubrication system.

workshop.

CYLINDER COMPRESSION - TEST

WARNING:

If

vehicle has been running, engine

oil

will

be

hot,

care must be taken when fitting

equipment

to prevent personal injury due to

scalding.

Test

Test

1.

Start and run engine until normal engine

operating temperature is achieved (thermostat

Equipment:
Compression pressure gauge

1.

Check lubricant is to correct level.

open).

2. Place vehicle on a ramp.

2. Remove all spark plugs.

3. Disconnect battery negative terminal and

3. Disconnect both coil negative (WB) leads

4.

Insert compression gauge, crank engine until

4.

Fit the test gauge.

reading stabilises.

5. Connect battery terminal.

5.

Expected readings, throttle fully open, battery

6.

Start and run engine to normal operating

fully

charged

170

-

180

psi

temperature.

6.

If compression is appreciably less than correct

7.

At

a steady engine speed

of

2400

rev/min

-

figure, or varies by more than

10%,

piston

minimum engine oil pressure reading should

rings or valves may

be faulty.

be

-

1.76

kg/cm².

7.

Low pressure in adjoining cylinders may

8.

I f there

is no oil pressure check for air lock

in

indicate a faulty head gasket.

system. See Service schedule.

9.

I f the pressure is

low, see Remove and

overhaul oil pump.

remove oil pressure switch.

RR2354E

ENGINE

ENGINE

NOISES

Excessive or obtrusive noise from the engine

compartment originates from three main sources:

A.

The exhaust system, which makes an

YES

-

Continue.

unmistakable and easy

to

diagnose noise.

B.

External components emit the greatest variety

2.

Is the lubricating pressure correct?

of noises, but are also easy to diagnose by
simply disconnecting the appropriate drive

YES

-

Drain engine oil and filter, and

belt.

examine

for

metallic

Engine internal mechanical noises which can

vary in volume and pitch and may be a

3.

Is

the oil contaminated

with

metal particles?

combination of, tapping

-

knocking or

YES

-

Suspect

faulty

big

end

rumbling, are the most difficult

to

diagnose.

bearings.

To

confirm

The following is therefore a guide to diagnosis

diagnosis,

short

out

the

of engine internal mechanical noises only.

ignition

to

each spark plug in

turn. The noise will disappear

Engine internal mechanical noises.

or be reduced when the

cylinder

with

the faulty big end

Single

or

multiple,

light

tapping

noise,

is shorted out.

particularly when engine

is cold.

See

Lubrication

system.

4.

If

noise is not conclusively diagnosed, check

the security

of the flywheel and crankshaft

1.

Is

engine oil level correct?

front pulley. Temporarily release the drive

belts to reduce general noise level and use

a

Heavy knocking noise (particularly on load and
when engine is hot). See Lubrication system.

1.

Is engine oil level correct?

NO

-

Top up

to

correct level.

NO -

See Engine oil pressure test.

contamination.

C.

NO

-

YES

-

Continue.

stethoscope

to locate source of noise.

2.

Is the lubricating pressure correct?
NO

-

YES

-

Suspect

valve

operating

Top up to correct level.

Heavy rumbling

noise

(particularly during hard

acceleration). See Lubrication system.

See Engine oil pressure test.

mechanism.

1.

Is

engine oil level correct?

NO

-

Top up

to

correct level.

3.

To confirm diagnosis, remove the rocker

YES

-

Continue.

covers and with the engine idling, insert

a

feeler gauge of 0,015mm between each

2. Is the lubricating pressure correct?

rocker and valve stem.

A faulty valve

NO

-

See Engine oil pressure test.

operating mechanism

will emit a different

YES

-

Drain engine oil and filter, and

noise when the feeler gauge

is

inserted. See

examine

for

metallic

Rocker shafts and valve gear.

contamination.

3.

Is the oil contaminated with metal particles?

YES

-

Suspect faulty main bearings.

If

noise is not conclusively

diagnosed, check the security
of the flywheel and crankshaft
front

pulley.

Temporarily

release the drive belts

to

reduce general noise level and
use a stethoscope

to

locate

source of noise.

ENGINE

ENGINE STARTING PROBLEMS

NOTE: References to the Electrical Trouble

Engine runs at high speed

but

will not idle

Shooting Manual

(ETM)

in the

following

(stops)

paragraphs are to the Range Rover ETM.

Engine idle speed erratic Engine starts

but

stops

However, only the specific circuits referred to in
the following paragraphs are applicable to the
Defender.

Engine fails to crank

Check brake vacuum connections.

See

ENGINE RUNNING PROBLEMS

immediately
Engine stalls Engine misfires/hesitation

1.

Multiport fuel injection. See ETM A1.

Brakes.

If

problem is not diagnosed continue.

1.

Is

battery in good state

of charge?

NO

-

Charge the battery.

YES

-

See ETM B1

2. Are

HT

leads correctly routed and clipped?

If

problem is not diagnosed repeat tests,

NO

-

See Electrical.

starting at

1.

YES

-

Continue.

Engine cranks but fails to start

3.

Is fuel supply, tank, pump, ventilation and

emission control systems in correct working
order or the fuel contaminated?

1.

Is the cranking speed fast enough

(120

rpm)?

NO

-

Charge the battery.

NO

-

See Fuel System.

If

necessary also

see ETM

B1

If problem is not diagnosed repeat tests,

YES

-

Continue.

starting at 1.

2.

Is there combustion in any cylinder?
NO

-

YES

-

Continue.

incorrectly adjusted?

and emission control systems in correct

NO

-

Continue.

working order or the fuel contaminated?

NO

-

See Fuel System or Emission

2. Is the Ignition and Multiport Fuel Injection

If

problem is not diagnosed repeat tests,

NO

-

See

ETM A1

starting at

2.

YES

-

Continue.

Engine lacks power/poor performance

See Ignition system tests. See
ETM A1

1.

Is accelerator pedal travel restricted or cable

YES

-

Check thickness of carpets.

3.

Are the fuel supply, tank, pump, ventilation

See Fuel System.

Control.

systems in order?

3. Is fuel supply, tank, pump, ventilation and

emission control systems in correct working
order or the fuel contaminated?

NO

-

See Fuel System or Emission
Control.

YES

-

Suspect valves held open by
hydraulic tappets due

to

high

oil pressure. See Engine oil
pressure test.

4.

Is oil pressure high?

YES

-

Remove oil filter and cooler
adaptor and check pressure
relief valve strainer gauze for
blockage and that the relief
valve is not stuck closed. See

Lubrication system.

Carry out cylinder compression
tests

to

determine condition of

head gaskets and valves.

See

Cylinder compression test.

NO

-

ENGINE

5.

Are cylinder compressions satisfactory?

Engine backfires into inlet system

NO

-

YES

-

Check

brake

vacuum

correct?

For overhaul, see Remove and

overhaul cylinder heads.

connections,

see

Brakes.

NO

-

See Electrical.

1. Is the Distributor, HT connections and routing

If problem is not diagnosed: Continue.

YES -

Continue.

6.

Are the brakes binding?

2. Is air fuel ratio correct?

YES

-

Investigate cause of binding.

NO

-

Check multiport fuel injection,

NO

-

Continue.

Check

brake

vacuum

connections,

see

Brakes.

Check the crank case and fuel
tank ventilation system. See

See Brakes.

see

ETM A1.

Engine backfires into exhaust system

1.

Are there any leaking joints/connections or

Emission control.

holes in the exhaust system?

YES

-

Continue.

YES

-

See Exhaust system.

N O

-

Continue.

3. Are cylinder compressions satisfactory?

NO

-

Carry out compression test

to

2. Is distributor

fitted

correctly,

HT leads in

check for

leaking gaskets

correct firing order and routed correctly?

valves

etc.

See

Cylinder

NO

-

See Electrical.

compression test.

YES

-

Continue.

For overhaul, see Remove and overhaul

3. Is air fuel ratio correct?

If

problem is not diagnosed: repeat tests

cylinder heads.

N O

-

Check multiport fuel injection,

starting at

1.

see ETM A1.
Check

brake

vacuum

connections,

see

Brakes.

Check the crank case and fuel
tank ventilation system. See
Emission control.

YES

-

Continue.

4.

Are cylinder compressions satisfactory?
NO

-

Carry out compression test to

check for

leaking gaskets

valves

etc.

See

Cylinder

compression test.

For overhaul,

see

Remove and

overhaul cylinder heads.

If problem is not diagnosed: repeat tests
starting at

1.