Mercedes-Benz E-class W124 - Repair manual and operation

26. Definition of malfunctions

Engine

The bent shaft of the engine does not rotate or rotates very slowly at start of the engine a starter

• Unreliable connections of plugs of the accumulator.
• The accumulator is discharged or faulty.
• The electrical wiring in a starter power-supply circuit is unreliably connected or faulty.
• The traction relay or contacts of the switch of a starter is faulty.
• Damage of a starter.
• There is no gearing of a gear wheel of a starter to a gear wreath of a flywheel.
• The tire of grounding of the engine is damaged or unreliably connected.

The bent shaft of the engine rotates, but the engine is not started

• There is no fuel.
• The accumulator is discharged. At the same time the bent shaft of the engine rotates very slowly.
• Accumulator plugs are unreliably connected.
• On models with petrol engines elements of system of ignition are damaged or at them there are moisture vapors.
• On models with petrol engines the electrical wiring in system of ignition is faulty.
• On models with petrol engines spark plugs are faulty or the interelectrode gap of a candle is not adjusted.
• On models with diesel engines the system of prestarting heating is faulty.
• On models with petrol engines with the carburetor the mechanism of the gate is faulty or incorrectly adjusted or the fuel cut-off valve gate is faulty.
• On models with diesel engines the engine stop valve is faulty.
• At models with diesel engines there is an air at fuel system.
• Serious mechanical defect of the engine.

The complicated start of the cold engine

• The accumulator is discharged.
• Unreliable connection or oxidation of plugs of the accumulator.
• On models with petrol engines spark plugs are faulty or the interelectrode gap of a candle is not adjusted.
• On models with diesel engines the system of prestarting heating is faulty.
• On models with petrol engines with the carburetor the mechanism of the gate is faulty or incorrectly adjusted or the fuel cut-off valve gate is faulty.
• On models with petrol engines the system of injection of fuel is faulty.
• On models with petrol engines the electrical wiring in system of ignition is faulty.
• On models with diesel engines the valve of the raised idling turns is incorrectly adjusted.
• A low compression in engine cylinders.

The complicated start of the hot engine

• The filtering element of the air filter is polluted.
• On models with petrol engines with the carburetor the mechanism of the gate is faulty or incorrectly adjusted or the fuel cut-off valve gate is faulty.
• On models with petrol engines the system of injection of fuel is faulty.
• A low compression in engine cylinders.

Strong noise during the work of a starter

• Teeths of 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 weakened or are absent.
• Internal details of a starter are worn-out or damaged.

The engine is started, but at once stops

• On models with petrol engines contacts in electric sockets are faulty or weakened.
• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.

Unstable operation of the engine on idling turns

• The filtering element of the air filter is polluted.
• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• On models with petrol engines spark plugs are faulty or the interelectrode gap of a candle is not adjusted.
• A low compression in engine cylinders.
• Camshaft cams are worn-out.
• The driving chain is incorrectly established.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.
• On models with diesel engines fuel nozzles are faulty.

Admissions of ignition on idling turns

• On models with petrol engines spark plugs are faulty or the interelectrode gap of a candle is not adjusted.
• On models with petrol engines high-voltage wires are faulty.
• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.
• On models with diesel engines fuel nozzles are faulty.
• On models with petrol engines there are cracks on an ignition distributor cover.
• An uneven or low compression in engine cylinders.
• Hoses of ventilation of a case are unreliably connected or damaged.

Admissions of ignition on all turns of the engine

• Pollution of the fuel filter.
• The fuel pump is faulty or gives fuel under low pressure.
• Pollution of the fuel tank or fuel tubes.
• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• On models with petrol engines spark plugs are faulty or the interelectrode gap of a candle is not adjusted.
• On models with petrol engines high-voltage wires are faulty.
• On models with diesel engines fuel nozzles are faulty.
• On models with petrol engines the ignition coil is faulty.
• On models with petrol engines there are cracks on an ignition distributor cover.
• An uneven or low compression in engine cylinders.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.

Acceleration of the engine happens to a delay

• On models with petrol engines spark plugs are faulty or the interelectrode gap of a candle is not adjusted.
• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.
• On models with diesel engines fuel nozzles are faulty.

The engine stops

• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• Pollution of the fuel filter.
• The fuel pump is faulty or gives fuel under low pressure.
• Pollution of the fuel tank or fuel tubes.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.
• On models with diesel engines fuel nozzles are faulty.

Reduction of engine capacity

• The driving chain is incorrectly established.
• Pollution of the fuel filter.
• The fuel pump is faulty or gives fuel under low pressure.
• On models with petrol engines spark plugs are faulty or the interelectrode gap of a candle is not adjusted.
• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.
• On models with diesel engines fuel nozzles are faulty.
• On models with diesel engines the fuel injection moment is incorrectly adjusted.
• Snubbing of wheels at the movement of the car.
• Incomplete inclusion of coupling (coupling slips).

Fire of a control lamp of pressure of oil at the working engine

• Low level of oil in the engine or oil of not required type is filled in.
• The oil pressure sensor is faulty.
• Radical bearings of a bent shaft and/or the oil pump are worn-out.
• Engine overheat.
• The safety valve of the oil pump is faulty.
• Pollution of the mesh filter of a maslopriyemny tube of the oil pump.

The engine continues to work after its switching off

• A thick layer of a deposit in combustion chambers.
• Engine overheat.
• On models with petrol engines with the carburetor the winding of the electromagnetic valve of a cut-off of fuel is faulty.
• On models with petrol engines with system of injection of fuel damage to system of injection of fuel.
• On models with diesel engines the electromagnetic valve of a stop of the engine is faulty.

Extraneous noises in the engine

Detonation or knocks at acceleration or at full load of the car

• On models with petrol engines the ignition advancing corner is incorrectly adjusted.
• On models with petrol engines spark plugs not of that type are established.
• Fuel with low octane number is used.
• On models with petrol engines an additional suction of air in the case of the carburetor or an inlet collector.
• A thick layer of a deposit in combustion chambers.
• On models with petrol engines with the carburetor jets or internal channels of the carburetor are hammered.
• On models with petrol engines with system of injection of fuel the system of injection of fuel or an injector is damaged or hammered.

The whistling or rattling noise

• On models with petrol engines laying of an inlet collector or the case of a carburetor/throttle is untight.
• Laying of a final collector or connection of a final collector with a reception exhaust pipe is untight.
• Damage of a vacuum hose of the vacuum amplifier of brakes.
• Burn-out of laying of a head of the block of cylinders.

Insignificant knock or jingle

• Wear of the mechanism of the drive of valves or camshaft.
• Wear or damage of auxiliary units of the engine (water pump, generator etc.).

Loud or deaf knock

• Conrod bearings of a bent shaft (the continuous strong knock decreasing at increase in loading) are worn-out.
• Radical bearings of a bent shaft (the strong knock increasing at increase in loading) are worn-out.
• Damage of the piston (it is especially notable during the operation of the cold engine).