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14. Main malfunctions

At start of the engine the crankshaft does not rotate:

 – accumulator plugs are unreliably connected or oxidized;
 – the accumulator is discharged or faulty;
 – violation of integrity of an electrical wiring in a starter chain;
 – the traction relay of a starter is faulty;
 – the starter is faulty;
 – teeths of a gear wheel of the drive of a starter or teeths of a gear wreath of a flywheel are worn-out;
 – the tire of grounding of the engine on the car case is disconnected.

The crankshaft rotates, but the engine is not started:

 – there is no fuel in a tank;
 – the accumulator is discharged (the crankshaft rotates very slowly);
 – are unreliably fixed or oxidized the accumulator plug;
 – elements of system of ignition (petrol engines) are damaged;
 – the wrong gap in spark plugs (petrol engines);
 – the system of prestarting heating (diesel engines) is faulty;
 – damage of system of injection of fuel (petrol engines);
 – the electromagnetic valve blocking fuel supply (diesel engines) is faulty;
 – air in fuel system (diesel engines);
 – mechanical malfunction of system of gas distribution.

Unstable start of the cold engine:

 – the accumulator is discharged;
 – accumulator plugs are unreliably connected or oxidized;
 – failure or interelectrode gaps in candles (petrol engines) are incorrectly adjusted;
 – the system of prestarting heating (diesel engines) is faulty;
 – the system of injection of fuel (petrol engines) is damaged;
 – damage of system of ignition (petrol engines);
 – a low compression in cylinders.

Unstable start of the hot engine:

 – the filtering element of the air filter is polluted;
 – damage of system of injection of fuel (petrol engines);
 – a low compression in cylinders.

At inclusion of a starter there are extraneous noises:


 – teeths on a gear wheel of a starter or a gear wreath of a flywheel are worn-out or broken;
 – bolts of fastening of a starter are absent or are unreliably tightened;
 – wear or damage of details of a starter.

Engine stop after start:

 – unreliable connection of elements of system of ignition (petrol engines);
 – an air suction in system of injection or an inlet collector (petrol engines);
 – damage of system of injection of fuel (petrol engines).

Unstable power setting idling:

 – the filtering element of the air filter is polluted;
 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – the interelectrode gap is incorrectly adjusted or spark plugs (petrol engines) are worn-out;
 – an uneven or low compression in cylinders;
 – cam-shaft cams are worn-out;
 – the gear belt of the drive of the mechanism of gas distribution is incorrectly established;
 – damage of system of injection of fuel (petrol engines);
 – nozzles (diesel engines) are faulty.

Admissions of ignition idling:

 – the interelectrode gap is incorrectly adjusted or spark plugs (petrol engines) are worn-out;
 – defective high-voltage wires (petrol engines);
 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – damage of system of injection of fuel (petrol engines);
 – nozzles (diesel engines) are faulty;
 – an uneven or low compression in cylinders;
 – hoses of ventilation of a case of the engine were disconnected or are untight.

Admissions of ignition in all range of turns of the engine:

 – the fuel filter is polluted;
 – it is faulty or the low pressure of supply of fuel the fuel pump;
 – the drainage opening of the fuel tank or fuel-supply lines is hammered;
 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – the interelectrode gap is incorrectly adjusted or spark plugs (petrol engines) are worn-out;
 – the ignition coil (petrol engines) is faulty;
 – the nozzle (diesel engines) is faulty;
 – the distributor breaker cover (petrol engines) is faulty;
 – an uneven or low compression in cylinders;
 – damage of system of injection of fuel (petrol engines).

Vibration of the engine at acceleration:

 – the interelectrode gap is incorrectly adjusted or spark plugs (petrol engines) are worn-out;
 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – damage of system of injection of fuel (petrol engines);
 – the nozzle (diesel engines) is faulty.

Unstable operation of the engine:

 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – the fuel filter is hammered;
 – malfunction or low pressure of supply of fuel fuel pump (petrol engines);
 – the drainage opening of the fuel tank or fuel-supply lines is hammered;
 – damage of system of injection of fuel (petrol engines);
 – nozzles (diesel engines) are faulty.

Low return of engine capacity:

 – the gear belt of the drive is incorrectly established;
 – the fuel filter is hammered;
 – it is faulty or the low pressure of supply of fuel the fuel pump;
 – an uneven or low compression in cylinders;
 – the interelectrode gap is incorrectly adjusted or spark plugs (petrol engines) are worn-out;
 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – the system of injection of fuel (petrol engines) is faulty;
 – nozzles (diesel engines) are faulty;
 – the moment of injection of fuel of the fuel pump (diesel engines) is incorrectly determined;
 – jamming of brakes;
 – coupling pro-slipping.

Backfires in the engine:

 – the gear belt of the drive of the mechanism of gas distribution is incorrectly established;
 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – damage of system of injection of fuel (petrol engines).

Low pressure of oil in the engine:


 – low level of oil or its wrong grade;
 – the oil pressure sensor is faulty;
 – bearings of the engine or the oil pump are worn-out;
 – engine overheat;
 – the safety valve of pressure of oil is faulty;
 – the mesh filter of an oil receiver is polluted.

The engine works after switching off of ignition:

 – an excessive deposit in combustion chambers;
 – engine overheat;
 – damage of system of injection of fuel (petrol engines);
 – the electromagnetic valve of a stop of the engine (diesel engines) is faulty.

Noise in the engine

Detonation in the engine at acceleration:

 – the ignition advancing corner (petrol engines) is incorrectly established;
 – the type of spark plugs does not correspond to demanded;
 – low octane number of fuel;
 – an air suction in system of injection, an inlet collector or hoses (petrol engines);
 – an excessive deposit in combustion chambers;
 – damage of system of injection of fuel (petrol engines).

The whistling or rattling noise:

 – the inlet collector or laying of a throttle (petrol engines) is untight;
 – laying of a final collector is untight;
 – vacuum hoses are untight;
 – laying of a head of the block of cylinders is punched.

The jingling noise:

 – the valvate mechanism or a cam-shaft is worn-out;
 – wear of auxiliary elements of the engine (water pump, generator, etc.).

Detonation or deaf noise:

 – bearings of the lower head of a rod are worn-out (noise decreases under loading);
 – radical bearings are worn-out (noise increases under loading);
 – blows to the piston (especially on the cold engine);
 – auxiliary elements of the engine (the water pump, the generator, etc.) are faulty.