In the article, we will consider possible malfunctions that may arise during the operation of a Renault / Dacia Sandero car.
The engine will not start
Starting the engine with the fuel injection system is the same at all ambient temperatures and the liquid in the engine cooling system.
To start the engine, you just need to turn on the starter without pressing the gas pedal, and the system will adjust itself to the necessary parameters of fuel supply and ignition timing.
If the engine does not start after three attempts, then:
Open the hood by pulling the drive handle towards you
We measure the oil level with a dipstick
In the K4M engine, the oil level should be between the upper and lower boundaries of the shaded area
In the K7J and K7M engine - between the lower and upper marks on the dipstick
Checking the coolant level
It must be between the MIN and MAX marks on the expansion tank.
We examine the engine. Pay attention to the drips of gasoline, oil and coolant.
We check the integrity of the wiring.
We check the fit of the pads of the wiring harnesses in the connectors of the ignition coils.
After inspecting the engine and systems, we try to start the engine again.
If the engine does not start on the first try, then press the gas pedal all the way and turn on the starter for two to three seconds.
In this mode, the cylinders are purged, no fuel is supplied through the injectors and no voltage is supplied to the spark plugs.
After purging the cylinders, we try to start the engine in normal mode, without pressing the gas pedal.
If, nevertheless, the engine does not start, then:
- the power supply system does not work;
- the ignition system does not work;
- the starting system does not work.
Starter will not turn on.
This could be caused by broken contacts and connections.
Open or short circuit in the starter switching circuits, traction relay malfunction.
If clicks are heard when the starter is turned on, then the reason is in a discharged battery, oxidized or weak contacts on the battery or starter.
Also, the reason may be a malfunction of the holding winding of the traction relay.
If the starter turns on, but the armature either does not rotate or rotates slowly.
The reason is that the battery is discharged, the contact connections are broken, the contacts of the traction relay are burnt, the collector is dirty or the brushes are worn out, interturn or short circuit in the starter windings.
If the starter is engaged, its armature rotates, but the flywheel is stationary.
The reason may be a weakening of the starter attachment to the clutch housing, damage to the flywheel or drive gear teeth, slipping of the drive freewheel clutch, breakage of the lever, drive ring or buffer spring of the starter drive.
If the starter does not turn off after starting the engine.
The reason is a malfunction of the starter freewheel clutch, sintering of the traction relay contacts. If such a malfunction occurs, the engine must be stopped immediately.
Checking the ignition system
The ignition system on the car is microprocessor-based (MPS3) of high energy.
The ignition coils convert a voltage of about 40,000 volts.
On K7J and K7M engines, it is necessary to check, with the ignition on, the integrity and fit of high-voltage wires in the sockets of the ignition module
It is necessary to check the serviceability of the ignition module
If the low voltage circuit of the ignition module is OK, check for a spark from the spark plugs.
We remove the high-voltage wire from any spark plug.
We insert a spare spark plug into the tip of the wire and press it with the metal part to the ground.
We ask the assistant to crank the engine crankshaft with the starter.
If there is no spark, the high voltage wires must be replaced.
On K4M engine:
We check the integrity and fit of the ignition coils on the spark plugs
Checking the ignition coils. To do this, remove the coil of the first cylinder.
We install a tested candle in the coil and press the candle against the metal part of the engine.
The assistant turns the engine crankshaft with the starter.
In this case, a strong spark should slip between the electrodes of the candle.
If there is no spark, the ignition coil must be replaced.
We check the rest of the coils in the same way.
During this check, it is necessary that there is a reliable contact of the spark plug with ground, otherwise the engine control unit or the high-voltage circuit of the ignition coil may be damaged.
Such a check should be done no more than five seconds so as not to damage the exhaust gas catalyst if unburned fuel from the engine cylinders enters it.
If after this check the engine does not start, you need to check the serviceability of the engine management system.
Checking the engine power supply system
The main criterion for the health of the fuel supply system is the fuel pressure in the rail.
It is recommended to ensure that the air filter is clean before this check.
We check the fuel pressure using a pressure gauge with adapters.
When the engine is idling, there should be a pressure of about 2.7 kgf / cm 2 in the rail.
Possible reasons for the decrease in pressure:
Defective fuel pump
Dirty fuel module strainer
It is possible to check the serviceability of the pump and the cleanliness of the filter only after removing the fuel module.
Fuel injection system malfunctions
On cars, a distributed fuel injection system is used.
Distributed injection is called multipoint injection because fuel is injected into each cylinder by a separate nozzle.
The fuel injection system helps to reduce the toxicity of the exhaust gases while improving the driving performance and fuel economy of the vehicle.
In the closed-loop engine fuel injection system, an exhaust gas catalytic converter and two oxygen concentration sensors are installed in the exhaust system, which provide feedback.
The sensors monitor the oxygen content in the exhaust gases, and the electronic control unit, based on their signals, maintains the air-fuel ratio at which the catalytic converter works most efficiently.
Before removing any components of the injection control system, disconnect the wire from the negative terminal of the storage battery.
Disconnect the battery only with the ignition off.
Do not start the engine if the battery cable lugs are loose.
Never disconnect the battery from the vehicle electrical system while the engine is running.
Disconnect the battery from the vehicle electrical system when charging.
Do not allow the electronic control unit (ECU) to heat above 65 ° C in working condition and above 80 ° C in non-working condition (for example, in a drying chamber after painting). If this temperature is exceeded, the ECU must be removed from the vehicle.
Do not disconnect or connect harness connectors from the computer with the ignition on.
Before performing electric arc welding on a vehicle, disconnect the battery wires and the computer harness connectors.
Perform all voltage measurements with a digital voltmeter with an internal resistance of at least 10 megohms.
The electronic components used in the injection system are designed for very low voltages, so they can easily be damaged by electrostatic discharge.
To prevent damage to the ECU by electrostatic discharge:
- do not touch the ECU plugs or electronic components on its boards with your hands;
- when working with the programmable read-only memory (EPROM) of the control unit, do not touch the microcircuit pins.
When operating in rainy weather, do not expose the electronic components of the fuel injection system to water.
Check the injection system in the following order:
- check the connection with the "mass" of the engine and storage battery;
- check the pressure regulator, fuel filter and fuel pump;
- check the fuses and relays for switching on the elements of the injection system;
- check the reliability of the contacts of the blocks with the wires of the injection system elements;
- check the sensors of the injection system.
The vast majority of fuel injection system malfunctions are caused by the failure of the following sensors:
- crankshaft position - complete failure of the injection system, the engine will not start;
- throttle position - loss of power, jerks and dips during acceleration, unstable idling;
- coolant temperature - difficulties with starting in frost.
You have to warm up the engine, maintaining the speed with the accelerator pedal.
When overheating, the power is significantly reduced, detonation appears;
- intake air temperature sensor - in case of sensor failure, difficulties with starting in frost, you have to warm up the engine, maintaining the speed with the gas pedal, when the engine overheats, the engine power decreases, detonation occurs.
- an absolute pressure (vacuum) sensor in the intake pipe - an increase in fuel consumption, a significant deterioration in dynamics, jerks and dips, problems with starting the engine;
- detonation - the engine is very sensitive to the quality of gasoline, increased tendency to knock;
- the control oxygen concentration sensor (lambda probe) - an increase in fuel consumption, a decrease in engine power, unstable idling.
Damage to the exhaust gas catalytic converter;
- diagnostic oxygen concentration sensor. Damage to the exhaust gas catalytic converter;
- vehicle speed sensor
- possible deterioration of the dynamic qualities of the car in modes with the use of maximum power (intensive acceleration);
Lost idle speed
To determine the causes of this malfunction, special diagnostic equipment is required, so in this case, contact a service station that specializes in repairing vehicles with injection engines.
Most often, this malfunction is caused by a failure of the idle speed control or air leaks through loose connections of the throttle body hoses.
If it was not possible to restore idle speed by replacing the regulator and tightening the hose clamps, contact a specialist.
Interruptions in engine operation
In case of interruptions, the engine idles unevenly, does not develop sufficient power, and consumes more gasoline.
Interruptions, as a rule, are explained by a malfunction of injectors or an electric petrol pump; spark plugs of one of the cylinders by sucking air into one of the cylinders. It is necessary to find the malfunction and, if possible, eliminate it.
Start the engine and let it idle.
Walk up to the exhaust pipe and listen for the sound of the exhaust.
You can bring your hand to the cut of the exhaust pipe - this way interruptions are felt better.
The sound should be smooth, "soft", of the same tone.
Pops from the exhaust pipe at regular intervals indicate that one cylinder is not working due to the failure of the spark plug, the absence of a spark on it, the failure of the nozzle, a strong suction of air into one cylinder or a significant decrease in compression in it.
Pops at irregular intervals are caused by dirty injector nozzles, excessive wear or dirty spark plugs.
If pops occur at irregular intervals, you can try to replace the entire set of candles yourself, regardless of the mileage and appearance, but it is better to do this after contacting a car service for diagnostics and repair of the engine control system.
If the popping is irregular, stop the engine and open the hood.
Check the condition of the ignition wiring harness and check the wiring harness on the ignition coils.
If there is damage to the wires, replace the entire ignition harness.
Remove the spark plugs. Take a close look at the candles and compare their appearance with the photographs shown in the article below.
If all plugs appear to be in good condition, reinstall the plugs and coils and connect the wiring harness pads to them.
Disconnect the harness connector from the 1st cylinder coil.
Start up the engine.
If the engine interruptions have not increased, replace the spark plug in the 1st cylinder with a known good one.
Put on the high voltage wire and start the engine.
If interruptions intensify, repeat the procedure sequentially with all cylinders in order to identify the faulty spark plug.
If, as a result of the measures taken, the engine interruptions are not eliminated, check the compression in each of the cylinders. Normal compression is more than 1.0 MPa (10 kgf / cm 2), the difference in compression values in the cylinders of more than 0.2 MPa (2 kgf / cm 2) indicates the need for engine repair.
Diagnostics by the appearance of spark plugs
Brownish or greyish-yellowish color and slight wear on the electrodes.
Matching the heat value of the spark plug to the engine and operating conditions.
Dry soot deposition indicates a rich mixture or late ignition.
Causes misfiring, difficult starting and erratic engine performance
Oily electrodes and spark plug insulator
The reason is the ingress of oil into the combustion chamber.
Oil enters the combustion chamber via valve guides or piston rings.
Causes difficult starting, cylinder skips and jerking of a running engine.
Make the necessary repairs to the cylinder head and piston group of the engine.
Replace spark plugs.
Deposition on the skirt of the insulator of iron oxides of a brownish-red color from anti-knock iron-containing additives (ferrocenes) to gasoline.
They are deposited in an even, dense layer.
When the engine is operating under heavy load with high temperature and pressure in the combustion chamber, oxides are converted into conductive paths of pure iron, which short-circuit the center electrode to ground.
This causes misfiring, a drop in engine power.
This could damage the catalytic converter.
Plaque is practically not removed mechanically and does not fade when moving at high speed.
If it is not possible to immediately replace with new candles, then place the candle in a rust converter, then clean the candle with a metal brush, rinse with water, and then with gasoline.
Early ignition. The insulator is white, but may be contaminated by misfiring sparks and deposits from the combustion chamber.
May cause engine damage.
It is necessary to check the correctness of the spark plug type, the cleanliness of the injector nozzles and the fuel filter, the operation of the cooling and lubrication system.
Cracked or chipped insulator
Damage caused by detonation.
May damage the piston.
Occurs when the knock sensor is malfunctioning.
Make sure the gasoline meets the requirements.
Mechanical damage to the candle
Damage can be caused by foreign objects trapped in the combustion chamber, and in the case of a plug with a long skirt, its electrodes can catch on the piston.
Remove the foreign object and replace the candle.
The car is moving in jerks
With regard to a car, a jerk is a short-term spontaneous change in the engine speed, regardless of the position of the accelerator pedal.
In daily use, there are usually a series of jerks. The extreme case of a jerk is a failure - a noticeable delay in the response of the engine to pressing the accelerator pedal.
Conventionally, three types of jerks can be distinguished:
- at the moment of the beginning of the movement;
- during overclocking;
- with steady motion, i.e. with a constant position of the accelerator pedal.
To determine the causes of jerks when driving a car with an injection engine, special diagnostic equipment is required, therefore, in this case, we recommend contacting a service that specializes in repairing fuel injection systems.
However, as practice shows, in most cases jerks are caused by insufficient fuel pressure in the fuel rail, malfunctions of the throttle position sensor.
If you have some skills, you can determine the cause of the jerks yourself.
Jerk at the start of movement
At the moment of the beginning of the movement, the limiting case of a jerk, a failure, most often takes place.
The most unpleasant sensations are associated precisely with the delay in the response of the engine to pressing the accelerator pedal.
Sometimes the engine even stalls.
A jerk occurs at the moment the throttle valve starts to open, when, according to the signal from the throttle position sensor, the ECU determines the moment of transition from idle to load mode and must increase the amount of fuel supplied through the injectors.
With insufficient pressure in the fuel line (even with an increase in the duration of injection), there is not enough fuel for a smooth start-off.
Jerks during acceleration
The cause of jerks during acceleration can be, as in the previous case, insufficient fuel pressure in the fuel line.
The electronic engine control unit, having received a signal from the throttle position sensor, about the intensive opening of the throttle to a large angle, seeks to maximize the fuel supply, but due to the reduced fuel pressure, it is not able to do this.
The reasons for this phenomenon and the method of verification are the same as in the previous case.
Jerks when driving
Such jerks are most often caused by a malfunction of the ignition system.
Diagnostics and repairs required.
On the way, you can try to do the following yourself:
- carefully inspect the engine compartment.
Turn off the ignition and check that the wiring harness pads are securely attached to the ignition coils.
Start up the engine and listen to its work: the crackle during high voltage breakdown "to ground" is weak, but distinct.
In complete darkness, a spark is clearly visible during breakdown;
- replace the spark plugs regardless of their condition and mileage.
Pay attention to the condition of the spark plugs: if it is abnormal, it may be necessary to repair the engine or its systems.
A specific reason for jerking during steady motion of a car with an injection engine may be a failure of the throttle position sensor.
Additional symptoms confirming a malfunction of this sensor are:
- uneven engine idling;
- decrease in maximum engine power.
The sensor is non-separable and therefore not repairable.
If the sensor is found to be faulty, it is replaced as an assembly.
The car accelerates poorly
There are many reasons for the deterioration of dynamics, the main ones can be defined as follows.
Engine malfunction: loss of compression in one or more cylinders, leakage of additional air into the intake tract of the engine.
Coking of the exhaust system or damage to the exhaust gas catalytic converter.
Power system malfunction: clogged injectors and fuel filter, fuel hoses.
Insufficient supply of the gasoline pump.
The use of low-quality fuel.
Malfunction of the ignition system: failure of the spark plug, breakdown of the high-voltage circuit of the system.
Malfunction of the engine management system: failure of the system sensors.
In case of failure of any sensor, the electronic control unit switches to work according to the backup program, which allows you to get to the garage or car service, but this reduces the power and economic characteristics of the engine.
Clutch slippage due to wear or misalignment.
Brake system malfunction: braking of one or more wheels while driving, incorrect parking brake adjustment.
Insufficient tire pressure.
Overloading the vehicle.
Full diagnostics of the car should be carried out by highly qualified technicians using special diagnostic equipment, so contact a car service.
You can independently carry out the following work:
Check and adjust the tire pressure.
Check the operation of the service brake system and the parking brake.
It is not necessary to remove the wheels for this.
Find a flat stretch of road and, in dry, calm weather, perform a run-down check.
The car must be fully fueled, only the driver is in the cabin.
Accelerate the vehicle to 50 km / h, level out the speed, and then disengage and coast to a complete stop.
Carry out another drive in the opposite direction.
The runout should be about 500 m.
Test the ignition system as described above.
Check the operation of the clutch of the car with a manual transmission.
The initial check is carried out on a level, unobstructed area.
Set the accelerator pedal to an increased idle speed - about 1500 min -1.
Apply the parking brake to the vehicle.
Depress the clutch and engage first gear.
Then begin to smoothly release the clutch pedal.
If the engine dies, the clutch is good and will not slip.
If the engine does not stall, the clutch is worn out, it must be replaced or the drive adjusted.
Check the serviceability of the engine management system.
Engine stalled while driving
Sooner or later, every driver may find himself in a situation where a car, a few moments ago, obeying all commands, suddenly stops responding to pressing the accelerator pedal, and red lights on the dashboard light up.
The engine stops working and the vehicle loses speed. What to do in such a situation?
Most importantly, don't be nervous! Turn on the hazard warning lights, depress the clutch pedal and, using the vehicle's inertia, try to carefully move to the edge of the carriageway and stop as far to the right as possible at the side of the road, and if possible, outside the carriageway.
Note that when the engine is not running, the vehicle's braking system will be less effective and may require more brake pedal pressure to brake.
Apply the parking brake.
If the vehicle comes to a stop on a slope, use wheel chocks.
In difficult driving conditions and on country roads, put up an emergency stop sign as provided by the Traffic Regulations. Now you need to find out and eliminate the problem that has arisen.
There are two main reasons:
- the ignition system does not work;
- the power supply system does not work.
First, determine if there is gas in the tank. Switch on the ignition and look at the fuel gauge.
If the yellow warning light for fuel reserve is off and the pointer arrow indicates the presence of fuel, it can be assumed that there is gas in the tank.
Open the hood and carefully examine the engine compartment. Pay attention to the integrity of all units.
Check if all wires are in place, if they are broken, burnt out, with damaged insulation.
Inspect the petrol hoses, engine fuel line, and fuel filter for leaks.
If gasoline leaks, under no circumstances start the engine until the malfunction is completely eliminated!
Inspect the coolant expansion tank for coolant leaks.
Also check the oil level in the engine crankcase. If everything is in order, proceed with the check of the ignition and power supply systems described earlier, but first check the condition of the timing belt.
If the belt is torn, the engine will not start for no apparent reason.
Oil pressure dropped
The vehicle's instrument cluster has a warning light for an emergency drop in engine oil pressure.
For the engine to operate reliably, a sufficiently high pressure must be maintained in the lubrication system at all times.
If, when the engine is running, the warning lamp for an emergency oil pressure drop comes on and remains on at an increased speed, then this is an alarming symptom.
Stop driving immediately, stop the engine and find out the reason.
Further operation of the engine at low oil pressure can lead to serious damage and high financial costs for repairs.
Open the hood. Do not rush to immediately check the engine oil level, let it drain into the oil sump, it will take two to three minutes.
During this time, carefully inspect the engine, find out if there are any fresh oil leaks on it.
Look under the front of the car to see if the engine oil sump is punctured or leaks.
If you find an oil leak from a punctured oil sump, try to temporarily repair it in place.
To do this, you can use a car camera, a piece of rubber, a rag, a wooden cork, etc.
A good result can be obtained from the use of modern repair materials such as "cold welding", available for sale in car dealerships.
Pay particular attention to the oil filter. Oil may leak from under the filter rubber gasket if it is damaged or the filter is loose.
If oil leaks from under the oil filter, it is sometimes sufficient to turn it clockwise a little.
Be careful to burn yourself on hot engine parts, so wear gloves and long sleeves.
If the oil level is below the lower mark on the scale, top up with oil.
Start up the engine. If the oil pressure drop warning lamp goes out at a normal level, you can continue driving.
If the lamp does not go out, check the serviceability of the oil pressure sensor.
It is installed on the side of the cylinder block facing the radiator of the cooling system.
Unscrew the original oil pressure sensor and install a mechanical pressure gauge in its place.
If, at a normal idle speed, the pressure is more than 0.06 MPa (0.65 kgf / cm 2) and increases with increasing speed, the sensor or its electrical circuit is faulty.
If you do not have a pressure gauge, it remains only to check the reliability of the contact in the block with the sensor wires or replace the sensor with a known good one.
If, after eliminating all visible causes, the oil pressure in the engine is insufficient (the emergency oil pressure drop lamp is on), diagnose and repair the engine.
Overheating of the engine
Malfunctions in the cooling system can cause the engine to overheat.
If you miss the moment of engine overheating, you may experience:
- breakdown of the cylinder head gasket;
- warpage of the head.
The instrument cluster contains an indicator "A" for the coolant temperature and a warning lamp "B" for engine overheating.
If the engine overheats, the indicator scale is fully shaded (at normal temperature, the bottom four divisions of the scale are shaded) and the warning lamp comes on.
Cooling system check
At the first signs of overheating, if the pointer scale is fully shaded, but vapors do not escape from under the hood, you need to turn on the maximum mode of the passenger compartment heater in order to reduce the temperature of the coolant.
Do not stop the engine immediately if there is no fluid leak from the burst hose or if another leak is formed.
Stop the engine.
Open the hood and locate the fluid leak.
Look under the front passenger floor mats and see if there is fluid leaking from the heater radiator under them.
If during the trip there is no antifreeze, then you can simply add water. Do not add cold water to an overheated engine.
The engine can overheat if the thermostat is faulty.
To check the thermostat, on a warm engine, feel the temperature of the lower hose connecting the radiator to the engine.
If the lower hose is cold, the thermostat is faulty, there is no fluid circulation through the radiator.
Fan motor failure is often the cause of engine overheating.
Start the engine, monitor the temperature and note if the cooling fan turns on when the engine overheats.
If it does not turn on, the cause may be a malfunction of the additional resistance, a blown fuse, a malfunction of the turn-on relay, oxidation of the contacts in the wiring harness block, or a burnout of the electric motor.
We replace the fuse "B" in the mounting block, in the engine compartment.
If the fan does not work after replacing the fuse, replace the "A" and "B" relays.
If, after these manipulations, the electric fan does not work, we check the fan motor.
To do this, we connect the wires directly to the electric motor and to the battery.
If the electric motor starts to work, then the wiring is faulty.
An important role in ensuring optimal temperature conditions is played by the expansion tank plug valve.
It maintains an overpressure in the system of at least 0.15 MPa (1.5 kgf / cm 2).
In this case, the boiling point of water rises to 120 ° C, and antifreeze to 130 ° C.
When the valve is jammed in the closed position during overheating, there is a significant excess of excess pressure [more than 0.2 MPa (2 kgf / cm 2)], which can lead to rupture of the expansion tank or breakdown of one of the hoses.
Once a year, rinse the radiator cells with a high-pressure water jet (at a special sink), directing the jet first towards the oncoming air flow, and then towards it to remove dirt, adhering insects and road debris from the radiator surface.
This partially restores the efficiency of the radiator.
The battery does not charge
There are two power sources on the car - a storage battery and a generator.
The storage battery is used when starting the engine and to supply the starter and other consumers with an electric current of 12 V when the engine is not running.
When the engine is running, the main source of current - the generator - provides electric current to all consumers, including the ignition system, and charges the battery.
If the red battery charging lamp on the dashboard lights up, it means that the current does not flow from the generator to the on-board network and the battery energy is consumed.
This stock is limited and depends on capacity. If the battery has been fully charged, you can drive to the garage without a generator, but it is best to try to fix the problem on the spot.
Electrical equipment check
Check if the accessory drive belt is torn.
If the belt breaks, we replace it.
If the belt is intact, check and, if necessary, adjust its tension.
Press on the belt branch with your thumb, if the distance between the centers of the pulleys is 180-400 mm, the deflection should be about 6 mm, and if the distance is 300-400 mm, the deflection should be 13 mm.
If, after checking the belt tension, the warning light is still on, check the wires connected to the "+" terminal of the battery.
We check the wires connected to the "-" terminal of the battery
We check the wires connected to the starter and to the generator
If, after the measures taken, the charging lamp still burns, then there is a malfunction in the generator itself.
If it seemed to you that when the engine was running, there were sounds that were not there before, immediately check if everything is in order with the engine.
Most often, engine knocks are associated with serious malfunctions, for diagnosis and elimination of which you will have to disassemble the engine in a service or garage. However, you can try to independently determine the cause of the knocks in order to decide whether to go to the car service on their own or in tow.
If you have the slightest doubt about the results of self-diagnosis, take out the towing rope.
Serious repairs to a damaged engine will cost more than towing services.
The knock of the main bearings is very dangerous; stop the engine immediately, you will have to go to a car service or garage in tow.
Low-pitched thump. It is heard in the lower part of the crankcase, it is noticeably amplified under load and with increasing speed.
Often its appearance is accompanied by a drop in oil pressure (the emergency oil pressure drop lamp is on almost constantly).
The knock of connecting rod bearings is very dangerous; stop the engine immediately, you will have to go to a car service or garage in tow.
The sound is rhythmic, ringing, metallic, medium tone. It increases significantly with increasing load and disappears completely when the spark plug is disconnected.
The knock of the piston fingers is dangerous; without loading the engine, you can drive to a car service or garage on your own.
Rhythmic, high-pitched tone with a sharp metallic tinge, audible in all engine operating modes and intensifies with increasing engine load.
Disappears completely when the spark plug is disconnected.
The knock of worn out pistons and cylinders is not dangerous; without heavily loading the engine, you can drive to a car service or garage on your own.
A sound reminiscent of the clatter of pottery. It is especially well heard on an unheated engine, decreases or disappears as it warms up.
The knock of valves is not dangerous; you can drive to a car service or garage on your own.
A metallic thud against the background of a general dull noise.
It is well listened to at low and medium crankshaft speed from the side of the cylinder head above the valve locations.
Detonation knocks are dangerous; however, avoiding heavy load on the engine, you can drive to the service center or garage on your own.
Voiced metal knocks, usually occurring when the car is accelerating.
The reason is a malfunction of the knock sensor, the use of low-octane fuel, engine overload when the overdrive is turned on too early, significant carbon formation in the combustion chambers.
It is necessary to select the right gear depending on the driving conditions, refuel with gasoline with an octane rating, which is recommended by the car manufacturer, check the knock sensor, apply a special additive to the fuel to remove carbon deposits on the valves and in the combustion chambers.
Knocks in the suspension and transmission
When extraneous knocks appear in the suspension of a moving car, it is necessary to immediately establish their source, regardless of whether it is a constant knock or appearing only when driving irregularities.
Check the suspension.
It is better to check the condition of the suspension by placing the car on an overpass, inspection ditch or lift, and if this is not possible, you can do this work, albeit with less convenience, on a free level area. In any case, you will need an assistant.
It is rather difficult to diagnose the serviceability of transmission units by the noise they emit.
If you are unable to pinpoint the source of the noise, contact a qualified technician.
Defective suspension assemblies repair or replace
The cause of knocking from below can be malfunctions not only of the suspension, but also of the steering of the car.
The state of the steering system significantly affects not only the convenience of driving, but also driving safety.
The cause of knocking and vibration on the steering wheel may be a faulty condition of the ball joints of the steering rods and the steering mechanism, the wheels of the car. Check steering.
A possible cause of vibration and shock to the steering wheel when driving at speeds over 70–80 km / h may be an imbalance in the front wheels. Contact a car service or tire fitting to check the balance of the front wheels.
If shocks and vibrations on the steering wheel appear at the moment you press the brake pedal, it is necessary to replace the brake pads, repair or replace the front brake discs.
Knocks in the suspension, causes and remedies
Cause of malfunction Remedy
Defective shock absorbers - Replace or repair shock absorbers
Loose bolts and nuts of the front suspension antiroll bar;
wear of pads and rubber-metal rods - Tighten rod mountings, replace worn pads
Damage, deformation of rubber-metal hinges, upper struts of shock absorber struts - Replace hinges, upper supports
Front suspension arm ball joints worn - Replace ball joints
Increased clearance in the front wheel hub bearings - Replace the bearing
Large wheel imbalance - Balance the wheels
Wheel rim deformed - Replace rim
Suspension spring settlement or breakage - Replace the spring
Worn rubber-metal hinges (silent blocks) of rear suspension arms - Replace rubber-metal hinges
Knock from suspension breakdown due to destruction of compression buffers - Replace damaged buffers
Frequent breakdowns of the rear suspension due to overloading of the rear axle - Avoid overloading
Possible transmission knocks, causes and remedies
Cause of malfunction Remedy
Noise when the clutch is disengaged
Release bearing worn or lack of lubrication - Replace bearing
Noise when engaging the clutch
Deformation or failure of the driven disc parts - Replace the driven disc
Noise in the gearbox
Insufficient oil level in gearbox - Check oil level and top up
Worn or broken bearings or gears - Replace damaged parts
Noise when shifting gears
Incomplete clutch release - Adjust the clutch release actuator
Synchronizers worn - Replace worn parts
Knock at the start of the vehicle
Wear on CV joints - Replace defective joints
Increased clearance in the meshing of the final drive gears - Adjust the clearance
Knock, clicks when driving a car in a corner
Outer CV joint worn - Replace defective joints
Causes of bumps on the steering wheel and remedies
Increased clearance in front wheel hub bearings - Replace bearings
Loose tie rod ball nuts - Tighten nuts
Increased clearance in the ball joints of the steering rods - Replace the ends of the steering rods
Increased play in the steering box - Repair the steering box
Loose steering gear attachment - Tighten the steering gear attachment