1993 FORD MONDEO engine overheat

2The function of these components is to
reduce the emission of unburned
hydrocarbons from the crankcase, and to
minimise the formation of oil sludge. By
ensuring that a depression is created in the
crankcase under most operating conditions,
particularly at idle, and by positively inducing
fresh air into the system, the oil vapours and
“blow-by” gases collected in the crankcase
are drawn from the crankcase, through the oil
separator, into the inlet tract, to be burned by
the engine during normal combustion.
Checking
3Checking procedures for the system
components are included in Chapter 1.
Component renewal
Cylinder head-to-air cleaner hose
4See Chapter 1.
Positive Crankcase Ventilation (PCV)
valve
5The valve is plugged into the oil separator.
Depending on the tools available, access to
the valve may be possible once the pulse-air
assembly has been removed (see Section 7).
If this is not feasible, proceed as outlined in
paragraph 6 below.
Oil separator
6Remove the exhaust manifold (see Chap-
ter 2, Part A). The Positive Crankcase
Ventilation (PCV) valve can now be unplugged
and flushed, or renewed, as required, as
described in Chapter 1.
7Unbolt the oil separator from the cylinder
block/crankcase, and withdraw it; remove and
discard the gasket.
8Flush out or renew the oil separator, as
required (see Chapter 1).
9On reassembly, fit a new gasket, and
tighten the fasteners to the torque wrench
settings given in the Specifications Section of
Chapter 2, Part B.
10The remainder of the refitting procedure is
the reverse of removal. Refill the cooling
system (see Chapter 1). Run the engine,
check for exhaust leaks, and check the
coolant level when it is fully warmed-up.
General information
1The exhaust gases of any petrol engine
(however efficient or well-tuned) consist
largely (approximately 99 %) of nitrogen (N
2),
carbon dioxide (CO
2), oxygen (O2), other inert
gases and water vapour (H
2O). The remaining
1 % is made up of the noxious materials
which are currently seen (CO
2apart) as the
major polluters of the environment: carbon
monoxide (CO), unburned hydrocarbons (HC),oxides of nitrogen (NO
x) and some solid
matter, including a small lead content.
2Left to themselves, most of these pollutants
are thought eventually to break down naturally
(CO and NO
x, for example, break down in the
upper atmosphere to release CO
2) having first
caused ground-level environmental problems.
The massive increase world-wide in the use of
motor vehicles, and the current popular
concern for the environment has caused the
introduction in most countries of legislation, in
varying degrees of severity, to combat the
problem.
3The device most commonly used to clean
up vehicle exhausts is the catalytic converter.
It is fitted into the vehicle’s exhaust system,
and uses precious metals (platinum and
palladium or rhodium) as catalysts to speed
up the reaction between the pollutants and
the oxygen in the vehicle’s exhaust gases, CO
and HC being oxidised to form H
2O and CO2and (in the three-way type of catalytic
converter) NO
xbeing reduced to N2. Note:
The catalytic converter is not a filter in the
physical sense; its function is to promote a
chemical reaction, but it is not itself affected
by that reaction.
4The converter consists of an element (or
“substrate”) of ceramic honeycomb, coated
with a combination of precious metals in such
a way as to produce a vast surface area over
which the exhaust gases must flow; the whole
being mounted in a stainless-steel box. A
simple “oxidation” (or “two-way”) catalytic
converter can deal with CO and HC only,
while a “reduction” (or “three-way”) catalytic
converter can deal with CO, HC and NO
x.
Three-way catalytic converters are further
sub-divided into “open-loop” (or
“uncontrolled”) converters which can remove
50 to 70 % of pollutants and “closed-loop”
(also known as “controlled” or “regulated”)
converters which can remove over 90 % of
pollutants.
5The catalytic converter fitted to the Mondeo
models covered in this manual is of the three-
way closed-loop type.
6The catalytic converter is a reliable and
simple device, which needs no maintenance
in itself, but there are some facts of which an
owner should be aware if the converter is to
function properly for its full service life.
(a) DO NOT use leaded petrol in a vehicle
equipped with a catalytic converter - the
lead will coat the precious metals,
reducing their converting efficiency, and
will eventually destroy the converter; it will
also affect the operation of the oxygen
sensor, requiring its renewal if lead-
fouled. Opinions vary as to how much
leaded fuel is necessary to affect the
converter’s performance, and whether it
can recover even if only unleaded petrol is
used afterwards; the best course of action
is, therefore, to assume the worst, and to
ensure that NO leaded petrol is used at
any time.
(b) Always keep the ignition and fuel systemswell-maintained in accordance with the
manufacturer’s schedule (Chapter 1) -
particularly, ensure that the air filter
element, the fuel filter and the spark plugs
are renewed at the correct intervals. If the
intake air/fuel mixture is allowed to
become too rich due to neglect, the
unburned surplus will enter and burn in
the catalytic converter, overheating the
element and eventually destroying the
converter.
(c) If the engine develops a misfire, do not
drive the vehicle at all (or at least as little
as possible) until the fault is cured - the
misfire will allow unburned fuel to enter
the converter, which will result in its
overheating, as noted above. For the
same reason, do not persist if the engine
refuses to start - either trace the problem
and cure it yourself, or have the vehicle
checked immediately by a qualified
mechanic.
(d) Avoid allowing the vehicle to run out of
petrol.
(e) DO NOT push- or tow-start the vehicle
unless no other alternative exists,
especially if the engine and exhaust are at
normal operating temperature. Starting
the engine in this way may soak the
catalytic converter in unburned fuel,
causing it to overheat when the engine
does start - see (b) above.
(f) DO NOT switch off the ignition at high
engine speeds, in particular, do not “blip”
the throttle immediately before switching
off. If the ignition is switched off at
anything above idle speed, unburned fuel
will enter the (very hot) catalytic converter,
with the possible risk of its igniting on the
element and damaging the converter.
(g) Avoid repeated successive cold starts
followed by short journeys. If the
converter is never allowed to reach its
proper working temperature, it will gather
unburned fuel, allowing some to pass into
the atmosphere and the rest to soak in
the element, causing it to overheat when
a long journey is made - see (b) above.
(h) DO NOT use fuel or engine oil additives -
these may contain substances harmful to
the catalytic converter. Similarly, DO NOT
use silicone-based sealants on any part of
the engine or fuel system, and do not use
exhaust sealants on any part of the
exhaust system upstream of the catalytic
converter. Even if the sealant itself does
not contain additives harmful to the
converter, pieces of it may break off and
foul the element, causing local
overheating.
(i) DO NOT continue to use the vehicle if the
engine burns oil to the extent of leaving a
visible trail of blue smoke. Unburned
carbon deposits will clog the converter
passages and reduce its efficiency; in
severe cases, the element will overheat.
(j) Remember that the catalytic converter
operates at very high temperatures -
9 Catalytic converter -
general information, checking
and component renewal
Emissions control systems 6•19
6
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REF•6Fault Finding
Engine 1
m mEngine backfires
m mEngine difficult to start when cold
m mEngine difficult to start when hot
m mEngine fails to rotate when attempting to start
m mEngine hesitates on acceleration
m mEngine idles erratically
m mEngine lacks power
m mEngine misfires at idle speed
m mEngine misfires throughout the driving speed range
m mEngine noises
m mEngine rotates but will not start
m mEngine runs-on after switching off
m mEngine stalls
m mEngine starts but stops immediately
m mOil pressure warning light illuminated with engine running
m mStarter motor noisy or excessively-rough in engagement
Cooling system 2
m
mCorrosion
m mExternal coolant leakage
m mInternal coolant leakage
m mOvercooling
m mOverheating
Fuel and exhaust systems 3
m
mExcessive fuel consumption
m mExcessive noise or fumes from exhaust system
m mFuel leakage and/or fuel odour
Clutch 4
m
mClutch fails to disengage (unable to select gears)
m mClutch slips (engine speed increases with no increase
in vehicle speed)
m mJudder as clutch is engaged
m mNoise when depressing or releasing clutch pedal
m mPedal travels to floor - no pressure or very little resistance
Manual transmission 5
m
mJumps out of gear
m mLubricant leaks
m mNoisy in neutral with engine running
m mNoisy in one particular gear
m mVibration
Automatic transmission 6
m
mEngine will not start in any gear, or starts in gears
other than Park or Neutral
m mFluid leakage
m mGeneral gear selection problems
m mTransmission fluid brown, or has burned smell
m mTransmission slips, shifts roughly, is noisy, or
has no drive in forward or reverse gears
m mTransmission will not downshift (kickdown) with
accelerator fully depressed
Driveshafts 7
m mClicking or knocking noise on turns (at slow speed on full-lock)
m mVibration when accelerating or decelerating
Braking system 8
m
mBrake pedal feels spongy when depressed
m mBrakes binding
m mExcessive brake pedal effort required to stop vehicle
m mExcessive brake pedal travel
m mJudder felt through brake pedal or steering wheel when braking
m mNoise (grinding or high-pitched squeal) when brakes applied
m mRear wheels locking under normal braking
m mVehicle pulls to one side under braking
Suspension and steering systems 9
m
mExcessive pitching and/or rolling around corners, or during
braking
m mExcessive play in steering
m mExcessively-stiff steering
m mLack of power assistance
m mTyre wear excessive
m mVehicle pulls to one side
m mWandering or general instability
m mWheel wobble and vibration
Electrical system 10
m
mBattery will not hold a charge for more than a few days
m mCentral locking system inoperative, or unsatisfactory in operation
m mElectric windows inoperative, or unsatisfactory in operation
m mHorn inoperative, or unsatisfactory in operation
m mIgnition warning light fails to come on
m mIgnition warning light remains illuminated with engine running
m mInstrument readings inaccurate or erratic
m mLights inoperative
m mWindscreen/tailgate washers inoperative, or unsatisfactory in
operation
m mWindscreen/tailgate wipers inoperative, or unsatisfactory in
operation
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Engine misfires throughout the driving speed range
m mFuel filter choked (Chapter 1).
m mFuel pump faulty or delivery pressure low (Chapter 4).
m mFuel tank vent blocked or fuel pipes restricted (Chapter 4).
m mVacuum leak at the inlet manifold or associated hoses (Chap-
ters 1, 4 and 6).
m mWorn, faulty or incorrectly-gapped spark plugs (Chapter 1).
m mFaulty spark plug HT leads (Chapter 1).
m mFaulty ignition coil (Chapter 5).
m mEngine management system fault (Chapters 1, 4, 5 and 6)
m mUneven or low cylinder compressions (Chapter 2, Part A).
Engine hesitates on acceleration
m
mWorn, faulty or incorrectly-gapped spark plugs (Chapter 1).
m mEngine management system fault (Chapters 1, 4, 5 and 6).
m mVacuum leak at the inlet manifold or associated hoses (Chap-
ters 1, 4 and 6).
Engine stalls
m mIdle speed control valve faulty (Chapter 4).
m mEngine management system fault (Chapters 1, 4, 5 and 6).
m mVacuum leak at the inlet manifold or associated hoses (Chap-
ters 1, 4 and 6).
m mFuel filter choked (Chapter 1).
m mFuel pump faulty or delivery pressure low (Chapter 4).
m mFuel tank vent blocked or fuel pipes restricted (Chapter 4).
Engine lacks power
m
mIncorrect ignition timing (Chapters 5 and 6).
m mEngine management system fault (Chapters 1, 4, 5 and 6).
m mTiming belt incorrectly fitted or incorrectly tensioned (Chapter 2,
Part A).
m mFuel filter choked (Chapter 1).
m mFuel pump faulty or delivery pressure low (Chapter 4).
m mUneven or low cylinder compressions (Chapter 2, Part A).
m mWorn, faulty or incorrectly-gapped spark plugs (Chapter 1).
m mVacuum leak at the inlet manifold or associated hoses (Chap-
ters 1, 4 and 6).
m mBrakes binding (Chapters 1 and 9).
m mClutch slipping (Chapter 8).
m mAutomatic transmission fluid level incorrect (Chapter 1).
Engine runs-on after switching off
m
mIdle speed excessively high (Chapters 4 and 6).
m mEngine management system fault (Chapters 1, 4, 5 and 6).
m mExcessive carbon build-up in engine (Chapter 2, Part A).
m mHigh engine operating temperature (Chapter 3).
Engine backfires
m
mIgnition timing incorrect (Chapters 5 and 6).
m mEngine management system fault (Chapters 1, 4, 5 and 6).
m mTiming belt incorrectly fitted or incorrectly tensioned (Chapter 2,
Part A).
m mVacuum leak at the inlet manifold or associated hoses (Chap-
ters 1, 4 and 6).
Oil pressure warning light illuminated with engine
running
m mLow oil level or incorrect oil grade (Chapter 1).
m mFaulty oil pressure warning light switch (Chapter 2, Part A).
m mWorn engine bearings and/or oil pump (Chapter 2).
m mHigh engine operating temperature (Chapter 3).
m mOil pressure relief valve defective (Chapter 2, Part A).
m mOil pick-up strainer clogged (Chapter 2, Part A).
Engine noises
Pre-ignition (pinking) or knocking during acceleration or under
load
m mIgnition timing incorrect (Chapters 5 and 6).
m mIncorrect grade of fuel (Chapter 4).
m mVacuum leak at the inlet manifold or associated hoses (Chap-
ters 1, 4 and 6).
m mExcessive carbon build-up in engine (Chapter 2, Part A).
Whistling or wheezing noises
m mLeaking inlet manifold gasket (Chapter 2, Part A).
m mLeaking exhaust manifold gasket or downpipe-to-manifold joint
(Chapters 1, 2 Part A, and 4).
m mLeaking vacuum hose (Chapters 1, 4, 6 and 9).
m mBlowing cylinder head gasket (Chapter 2, Part A).
Tapping or rattling noises
m mFaulty hydraulic tappet(s) (Chapter 2, Part A).
m mWorn valve gear or camshaft (Chapter 2, Part A).
m mWorn timing belt or tensioner (Chapter 2, Part A).
m mAncillary component fault (water pump, alternator, etc) (Chap-
ters 3 and 5).
Knocking or thumping noises
m mWorn big-end bearings (regular heavy knocking, perhaps less
under load) (Chapter 2, Part B).
m mWorn main bearings (rumbling and knocking, perhaps worsening
under load) (Chapter 2, Part B).
m mPiston slap (most noticeable when cold) (Chapter 2, Part B).
m mAncillary component fault (water pump, alternator, etc) (Chap-
ters 3 and 5).
REF•8Fault Finding
2 Cooling system
Overheating
m mInsufficient coolant in system (Chapter 1).
m mThermostat faulty (Chapter 3).
m mRadiator core blocked or grille restricted (Chapter 3).
m mRadiator electric cooling fan(s) or coolant temperature sensor faulty
(Chapter 3).
m mEngine management system fault (Chapters 1, 4, 5 and 6).
m mPressure cap faulty (Chapter 3).
m mAuxiliary drivebelt worn or slipping (Chapter 1).
m mIgnition timing incorrect (Chapters 5 and 6).
m mInaccurate coolant temperature gauge sender (Chapter 3).
m mAir-lock in cooling system (Chapter 1).
Overcooling
m
mThermostat faulty (Chapter 3).
m mInaccurate coolant temperature gauge sender (Chapter 3).
External coolant leakage
m
mDeteriorated or damaged hoses or hose clips (Chapter 1).
m mRadiator core or heater matrix leaking (Chapter 3).
m mPressure cap faulty (Chapter 3).
m mWater pump seal leaking (Chapter 3).
m mBoiling due to overheating (Chapter 3).
m mCore plug leaking (Chapter 2, Part B).
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REF•19Index
Oil pressure warning light switch - 2A•22
Oil pump - 2A•21
Oil seals - 2A•13, 2A•22, 7A•2, 7B•3, REF•4
Oil separator - 6•19
Open-circuit - 12•4
Overcooling - REF•8
Overhead console - 11•22
Overheating - REF•8
Oxygen sensor - 6•11, 6•12, 6•13
P
Pads - 9•3, 9•8
Pedals - 1•17, 4•5, 8•3, 9•10, 9•11
Piston rings - 2B•19
Pistons - 2B•12, 2B•17, 2B•21, 2B•22
Pitching and/or rolling around corners -
REF•11
Plastic components - 11•4
Plenum chamber - 4•3
Poisonous or irritant substances - 0•5
Pollen filter - 1•20, 3•8
Position sensor - 5•4, 6•10, 6•11, 6•12
Positive Crankcase Ventilation (PCV)
system - 1•23, 6•18, 6•19
Power steering - 1•8, 1•10, 6•11, 6•12,
6•13, 10•20, 10•21, 10•22
Power steering fluid - 1•2
Pressure-control relief valve - 9•13
Pressure-cycling and pressure-regulating
switches - 3•10
Project vehicles - 0•4
Pulse-air - 6•17, 6•18
Purge solenoid valve - 6•14
R
Radiator - 3•4, 3•5
Radiator grille - 11•5
Radio - 12•21, 12•22
Radio aerial - 12•22
Reading light - 12•11
Rear light cluster - 12•9, 12•13
Rear window - 12•8, 12•21
Relays - 12•5
Repair procedures - REF•4
Resonator (engine compartment) - 4•3
Respraying - 11•3
Reversing light switch - 7A•3
Road test - 1•20
Roadwheels - 1•17, 1•18, 1•20
Roll-over valves - 4•8
Routine maintenance and servicing- 1•1et
seq
Rubber gaiters- 1•18, 8•7, 8•9, 10•21
Rust holes in bodywork - 11•3
S
Safety first! - 0•5
Scalding - 0•5
Scratches in bodywork - 11•3
Screw threads and fastenings - REF•4
Seat belts - 0•8, 1•13, 11•19, 11•20Seats - 0•8, 11•18, 12•8
Selector assembly - 7B•2
Selector cable - 7B•2
Selector lever position sensor - 7B•2
Selector panel illumination - 12•11
Service indicator - 12•17, 12•18
Servo unit - 9•12, 9•13
Shock absorbers - 0•8, 0•9, 10•14
Shoes - 9•6
Short-circuit - 12•4
Sidelight - 12•9
Solenoid renewal - 5•8
Spare parts - REF•5
Spark plugs - 1•23
Speakers - 12•22
Speed control - 12•20
Speed sensor - 6•11, 6•12, 6•13
Speedometer - 7A•2, 7A•3, 7B•2, 7B•3,
12•15
Springs - 0•9
Starter motor - 5•7
Starter motor fault - REF•7
Starting system - 5•6
Steering - 0•7, 0•8, 0•9, 1•17, 1•20
Steering angles - 10•22
Steering column - 10•18, 10•20
Steering fault - REF•11
Steering knuckle - 10•5
Steering wheel - 10•17
Stop-light switch - 9•15
Striker - 11•13
Struts - 10•6, 10•7, 10•10, 10•12
Sump - 2A•19
Sun visor - 11•20
Sunroof - 11•18, 12•7
Suspension and steering systems- 0•8,
0•9, 1•17, 1•18, 1•20, 10•1et seq
Suspension and steering systems fault
finding - REF•11
Switches - 2A•22, 3•4, 3•5, 3•10, 4•8-
6•11, 6•12, 6•13, 7A•3, 9•15, 11•17,
12•6, 12•7, 12•8, 12•11, 12•18, 12•20
T
Tailgate - 1•8, 1•10, 11•15, 11•16, 12•17,
12•20, REF•12
Tappets - 2A•14
TCS inhibitor switch - 9•15
TCS throttle actuator - 9•15
Temperature gauge fault - REF•12
Thermostat - 3•3, 3•4
Throttle actuator - 9•15
Throttle housing - 4•9
Throttle potentiometer - 6•11, 6•13
Tie-bar - 10•13, 10•16
Timer module - 12•5
Timing - 5•4, 6•10
Timing belt - 1•26, 2A•10, 2A•13
Tools - REF•1, REF•3, REF•4
Top Dead Centre (TDC) for No 1 piston -
2A•6
Towing - 0•11
Track rod end - 10•22Traction Control System - 9•15, 12•7
Transmission- 1•11, 1•17, 2A•24, 2B•3,
2B•4, 7A•1 et seq, 7B•1 et seq, 12•11
Trim mouldings - 11•17
Trim panels - 11•6, 11•20
Trip computer - 12•17
Tyre wear - REF•11
Tyres - 0•10, 1•8
U
Underbody check - 1•19
Upper suspension arm - 10•16
V
Vacuum hoses - 1•15
Vacuum servo unit - 9•12, 9•13
Valve clearances - 2A•5
Valves - 2B•10, 2B•11
Vehicle identification - 0•8, REF•5
Vehicle pulls to one side - REF•10, REF•11
Vehicle speed sensor - 6•11, 6•12, 6•13
Ventilation system - 1•20, 3•7
Voltage regulator - 5•6
W
Warning lights - 12•11
Warning system - 12•17
Washer jets fault - REF•12
Washer nozzle - 12•21
Washer pump fault - REF•12
Washer reservoir and pump - 12•20
Washer system - 1•8, 1•10, 12•18, 12•20
Water pump - 3•6
Weights - 0•6
Wheel alignment - 10•22
Wheel arch liner - 11•24
Wheel bearings - 0•9
Wheel changing - 0•11
Wheel cylinders - 9•8
Wheel sensors - 9•14
Wheel wobble - REF•11
Wheels - 0•10, 1•17, 1•18, 1•20
Wheels locking - REF•11
Window glass - 11•8
Window regulator - 11•9
Windows - 11•17, 12•7, 12•8, 12•21,
REF•12
Windscreen - 0•7, 1•8, 1•10, 11•17, 12•6,
12•8, 12•16, 12•20, 12•21, REF•12
Wiper arms - 12•16
Wiper blade - 1•10
Wiper blade fault - REF•12
Wiper motor - 12•16, 12•17
Wipers - 12•6
Wiper fault - REF•12
Wiring - 1•15
Wiring diagrams- 12•23et seq
Working facilities - REF•3
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