Next First published 5
September 2001
Alfa Romeo fault diagnosis. Some common symptoms and perhaps some
reasons. Thanks to Highwood Motor Co.
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Engine fails to turn when starter operated
Starter motor turns engine slowly but fails
to start
Starter motor spins without turning engine
Engine turns normally but fails to start
Engine fires but will not run
Engine cuts out and will not restart
Engine misfires before cutting out - fuel fault
Engine cuts out - other causes
Engine overheats
Low engine oil pressure
Engine noises
Whistling or wheezing noises
Tapping or rattling
Knocking or thumping
Engine fires but will not run
Difficult starting when cold
Difficult starting when hot
Engine slow to warm up
Engine idles roughly
Engine lacks power
Engine misfires throughout speed range
Poor engine braking
Pre-ignition (pinking) during acceleration
Engine runs on after switching off
Low oil pressure (verify accuracy of sender before
dismantling)
Excessive oil consumption
Oil contaminated with water
Oil contaminated with fuel
Oil smoke
Unusual mechanical noises
Cooling system overheating
Engine running too cool
Loss of coolant
Heater gives insufficient output
Fu1iel system - Fuel smell
Smel1 of petrol when engine is idling
Excessive fuel consumption for reasons not covered by
leaks or float chamber faults
Difficult starting, uneven running, lack of power,
cutting out
Difficult starting when cold
Difficult starting when hot
Engine does not respond properly to throttle
Engine idle sped drops when hot
Engine runs on
Ignition system - Mechanical breaker system
Engine fails to start
Engine starts and runs but misfires
Engine overheats, lacks power
Electronic type - Engine fails to start
Clutch - transmission
Difficulty in engaging gear (grinding)
Clutch spin (failure to disengage) so that gears
cannot be meshed
Clutch slip, increase in engine but speed does not increase,
road speed
Noise evident when clutch pedal depressed
Noise evident as clutch pedal released
Weak or ineffective synchromesh
Jumps out of gear
Excessive noise in transmission
Difficulty in engaging gears
Noise when cornering
Braking system
Excessive pedal travel
Pedal feels spongy or soggy
Pedal feels springy
Excessive effort required to stop car
Brakes pull to one side
Pedal vibrates when brakes applied
Brakes squeal
Top Cooling system
overheating
- Insufficient coolant in system
- Pump ineffective due to slack drivebelt
- Radiator blocked either internally or externally
- Kinked or collapsed hose causing coolant flow restriction
- Thermostat not working properly
- Engine out of tune
- Ignition timing retarded or auto advance malfunction
- Cylinder head gasket blown
- Cylinder head gasket blown
- Exhaust system partially blocked
- Engine oil level too low
- Brakes binding
Top Engine running
too cool
- Faulty thermostat
- Incorrect or missing thermostat
Top Loss of coolant
- Loose hose clips
- loses perished or leaking
- Radiator leaking
- Radiator leaking
- Blown cylinder head gasket
- Cracked cylinder block or head
Top Heater gives
insufficient output
- Engine overcooled (see above)
- Heater matrix blocked
- Heater controls maladjusted or broken
- Heater control valve jammed or otherwise defective
Top Fuel system -
Fuel smell
- Smell of petrol when engine is stopped
- Leaking fuel lines or unions
- Leaking fuel tank
Top Smell of petrol
when engine is idling
- Leaking fuel line unions between pump and carburettor
- Overflow of fuel from float chamber due to wrong level
setting,
- ineffective needle valve or punctured float
Top Excessive fuel
consumption for reasons not covered by leaks or float chamber
faults
- Worn jets
- Over-rich setting
- Sticking mechanism
- Dirty air cleaner element
Top Difficult
starting, uneven running, lack of power, cutting out
- One or more jets blocked or restricted
- Float chamber fuel level too low or needle valve sticking
- Float chamber fuel} level too low or needle valve
- Fuel pump not delivering
Top Difficult
starting when cold
- Choke control
- Insufficient use of manual choke
- Weak mixture
Top Difficult
starting when hot
- Excessive use of manual choke
- Accelerator pedal pumped before starting
- Vapour lock especially in hot weather or at high altitude)
- Rich mixture
Top Engine does not
respond properly to throttle
- Faulty accelerator pump
- Blocked jets
- Slack in accelerator cable
Top Engine idle sped
drops when hot
- Incorrect air cleaner intake setting
- Overheated fuel pump
Top Engine runs on
- Idle speed too high
- Too rich mixture
Top Ignition system -
Mechanical breaker system Engine
fails to start
- Loose battery connections
- Discharged battery
- Oil in contact points
- Disconnected ignition leads
- Faulty condenser
Top Engine starts and
runs but misfires
- Faulty spark plug
- Cracked distributor cap
- Cracked rotor arm
- Worn advance mechanism
- Incorrect spark plug gap
- Incorrect contact points gap
- Faulty condenser
- Faulty coil
- Incorrect timing
- Poor engine / transmission earth connections
Top Engine overheats,
lacks power
- Seized distributor weights
- Perforated vacuum pipe
- Incorrect ignition timing
Top Eectronic type -
Engine fails to start
- Excessive gap on TDC sensor
- TDC or engine speed sensor short circuited or earthed
- Defective ignition control unit
- Control unit multiplug contacts corroded
- Defective coil
Top Engine lacks
power, high fuel consumption
- Incorrect ignition advance
- TDC sensor incorrectly set
- Distributor vacuum hose blocked
Top Clutch -
transmission Difficulty in engaging gear
(grinding)
- Clutch cable adjustment incorrect
- See under Clutch spin
- Judder when taking up drive
- Engine / transmission mountings loose or worn
- Driven plate linings contaminated or worn
- Pressure plate loose or defective
Top Clutch spin
(failure to disengage) so that gears cannot be meshed
- Incorrect release bearing to pressure plate clearance on
splines (may occur after vehicle standing idle for long
periods)
- Damaged or misalign pressure plate assembly stretched or broken
Top Clutch slip,
increase in engine but speed does not increase, road speed
- Incorrect cable adjustment
- Driven plate linings worn or contaminated
- Pressure plate defective
Top Noise evident
when clutch pedal depressed
- Release arm pivots unlubricated
- Release bearing worn, loose or unlubricated
- Worn or damaged pressure plate
Top Noise evident as
clutch pedal released
- Distorted driven plate
- Broken or weak driven plate cushion coil springs
- Incorrect pedal adjustment
- Weak or broken clutch pedal return spring
- Distorted or worn input shaft
- Release bearing loose on retainer hub
Top Weak or
ineffective synchromesh
- Synchro bulk rings worn, split or damaged
- Synchromesh units worn, or damaged
Top Jumps out of gear
- Gearchange mechanism worn
- Synchromesh units badly worn
- Selector fork badly worn
Top Excessive noise
in transmission
- Incorrect grade of oil in gearbox or oil level too low
- Gearteeth excessively worn or damaged
- Intermediate gear thrust washers worn allowing excessive end
play
- Worn bearings
- Worn universal joint, tickling noise when driving off
- Heavy knocking when driving off is often the propeller shaft
support bearing
- Ticking noise when driving off is often universal joint at rear
axle.
Top Difficulty in
engaging gears
- Clutch pedal adjustment incorrect
- Hydralic fluid level too low
Top Noise when
cornering
- Wheel bearing or driveshaft fault
- Differential fault
Top Braking system Excessive pedal travel
- Pads or shoes excessively worn
- Incorrect pedal or servo pushrod adjustment
- Automatic adjusters faulty
- Seized wheel cylinder or calliper piston
- Master cylinder seals worn
Top Pedal feels
spongy or soggy
- Air in hydraulic system
- Low fluid level
- Loose connections
- Flexible hose perished
- Defective wheel cylinder or calliper seal
Top Pedal feels
springy
- New pads or linings not bedded-in
- Master cylinder mounting loose
Top Excessive effort
required to stop car
- Worn or contaminated linings or pads
- Incorrect grade of lining or pad material
- Servo vacum hose leaking or disconnected
- Faulty servo or non-return valve
- Seized calliper or wheel cylinder piston
- I.e. circuit defective on dual circuit hydraulic system
Top Brakes pull to
one side
- Friction linings contaminated on one side of car
- Seized hydraulic piston on one side of car
- Different types of linings fitted on different sides of car,
or new linings on one side only
- Seized automatic adjuster on one side of car
Top Pedal vibrates
when brakes applied
- Discs or drums distorted
- Friction linings excessively worn
- Loose backplate or calliper mounting bolts
Top Brakes squeal
- Disks rusty or damp, often temporary fault with no action needed.
- Dust or grit in brake drums
- Linings excessively worn
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