Engine — fault diagnosis

Symptom/Cause (causes)

The engine does not turn over with the starter/

• There is no current flowing to the starter
• Battery is dead or faulty
• Poor contact at battery terminals
• Faulty starter switch or solenoid or open in starter wiring
• Bad "weight" engine.

Current flows to the starter/

• Starter drive gear stuck
• The starter is faulty.

The engine turns over, but does not start/

• No spark at spark plugs
• Damp ignition wires or distributor cap
• Ignition wires are not connected to spark plugs
• Low voltage wires are shorted or disconnected
• Breaker contacts are dirty, incorrectly adjusted or pitted (engine 1.3) *
• Capacitor faulty (engine 1.3) *
• Ignition switch faulty
• Ignition wires are not connected correctly
• Ignition coil is faulty
• Breaker contact spring is grounded or broken (engine 1.3) *

There is no fuel in the float chamber or on the jets/

• Empty fuel tank
• Vacuum plug in the fuel line (may occur in hot weather or at high altitudes above sea level)
• Float chamber needle valve clogged
• Fuel pump filter clogged
• The jets are clogged
• The fuel pump is faulty.

The engine stalls and will not start again/

• Excess fuel in the cylinders or carburetor flooding
• Too much suction (over-rich mixture) or damp spark plugs
• The float is damaged or leaking or the valve needle does not seat in place
• The upper position of the float is incorrectly adjusted.

No spark on spark plugs/

• Sudden malfunction of the ignition system
• Ignition system malfunction (misfire was observed before complete failure)
• Malfunction of the ignition system - during heavy rains or after driving through a deep puddle.
• No fuel on the jets

Fuel tank empty/

• The fuel tank breather is clogged
• Carburetor clogged
• Water has entered the fuel system
• The fuel pump is faulty.

Missing flash or rough engine idling/

• Periodic loss of spark on the candles
• Ignition wires come loose
• Poor contact at battery terminals
• The battery grounding wire has come loose where it is attached to the body
• Bad "weight" engine
• The low voltage wires on the ignition coil are loose
• The fastening of the low voltage wire to the distributor is loose
• Spark plugs are burned out or the spark gap is incorrectly adjusted
• Breaker contacts are dirty, incorrectly adjusted or pitted (engine 1.3) *
• Tracking along the inner surface of the distributor cover
• Ignition too late
• The ignition coil is faulty.

Engine fuel starvation/

• Mixture too lean
• Air leaking into the carburetor
• Air leakage into the connection between the intake manifold and cylinder head or between the intake manifold and carburetor
• The fuel pump is faulty.

The engine does not develop enough power/

• Mechanical wear (bad compression)
• Burnt valves
• Valves stick or leak
• Valve springs are weakened or broken
• Worn valve guides or valve stems
• Worn pistons and piston rings.

The working mixture leaks from the cylinders (bad compression) /

• Burnt valves
• Valves stick or leak
• Worn valve guides or valve stems
• Valve springs are weakened or broken
• Cylinder head gasket leaking (accompanied by increased noise)
• Worn pistons and piston rings.
• Cylinders are worn or scratched.

Incorrect adjustment/

• The ignition timing is incorrectly set
• The gap between the breaker contacts is incorrectly set (engine 1.3) *
• The spark gap of the spark plugs is incorrectly set
• Carburation is too strong or too weak.

Problems with carburetion or ignition/

• The breaker contacts are dirty (engine 1.3) *
• Fuel filter clogged
• Air filter clogged
• Malfunctions in the operation of ignition timing regulators
• The fuel pump is faulty - fuel starvation.

Excessive oil consumption/

• Oil burns
• Excessive wear on valve stems and guides
• Worn piston rings
• Worn pistons and cylinders
• Piston ring locks are too large - the working mixture passes behind the piston
• The return lubrication channels are clogged.

Oil consumption due to leaks/

• Oil filter gasket leaking
• Camshaft cover gasket is leaking
• Pan gasket leaks
• The pan plug is loose.

The engine makes an unusual noise/

• Excessive clearances due to mechanical wear
• Worn valve mechanism (knocking noise coming from the cylinder head) **
• Worn connecting rod bearings (heavy regular blows)
• Worn main bearings (rumble and vibration)
• Worn crankshaft (shock, noise and vibration)
• The hydraulic valve tappet is faulty.

Detonation when revving up/

• Fuel octane number too low
• Ignition too early
• Carbon accumulation in the cylinder head
• Ignition adjusted incorrectly
• Mixture too lean
• Engine overheating

* Models before 1982

* * Some knocking noise from the hydraulic tappets is normal when the engine is first started after a major overhaul. After the oil pressure in the pushers reaches the required value, the knocking noise will disappear. In addition, when starting a worn engine for the first time after a long period of inactivity, a knocking noise may also occur, which will disappear over time.