Diesel generator diesel engine fault repair

1. Diesel engine is difficult to start or cannot start

(1) Failure phenomenon. (When ambient temperature is higher than 5 ℃) Under normal circumstances, the diesel engine should be generally smooth starts within 5s. Sometimes it takes several iterations to start successfully, which is normal. If after repeatedly stalled starter can not start, or start immediately after, you can not enter the normal operation should be regarded as the starting fault.

(2) Analysis of the cause. The three necessary conditions for starting the diesel engine are: good atomized diesel and sufficient air to be injected into the combustion chamber in time, a certain starting speed, and a certain compression pressure in the combustion chamber to obtain the temperature required for spontaneous combustion of the diesel. If one of the above three conditions is not available, that is, a system with this condition fails, it will start unsuccessfully. The main causes of starting failures are as follows:

1 Fuel supply system failure

a. The fuel tank switch is not open, there is no oil in the fuel tank, and the fuel tank vent is blocked. The tubing is broken, bumped or blocked, and the pipe joint is loose and leaking. There is air in the oil circuit, resulting in air blockage, or the diesel filter is clogged, making the fuel supply poor.

b. Diesel contains moisture, and it is difficult to self-ignite after diesel is injected into the cylinder.

c. The oil pump does not pump oil and the system has no fuel supply.

d. The fuel injection pump is faulty, such as not spraying oil, too much oil or too little. Injector failure, such as too little or no fuel injection, poor atomization, etc.

2 Inlet and exhaust system failure. The air filter and the intake pipe are blocked, the intake air is blocked, and the intake air volume of the combustion chamber is insufficient. The exhaust pipe and the muffler are blocked, the exhaust gas is not smooth, the exhaust gas is not clean, and the fresh air in the combustion chamber is insufficient.

3 Electric starting system failure

a. Wiring error or open circuit, the starter motor is faulty and cannot be turned.

b. The battery voltage is low, which makes the starter motor unable to drive the diesel gear ring to rotate.

c. The starter motor gear cannot be embedded in the ring gear of the diesel engine.

4 Compressor compression pressure is insufficient

a. The valve and cylinder head gasket are not tightly sealed and leak, and the piston, piston ring and cylinder sleeve are leaking due to serious wear.

b. The compression ratio becomes smaller due to the cylinder head gasket being too thick or the cylinder head and piston crown are corroded seriously.

5 It is difficult to start due to low ambient temperature.

(3) Treatment method. When there is a difficulty in starting the operation, it is generally necessary to check whether there is oil in the fuel tank, whether the fuel tank switch is open, whether the fuel tank vent is blocked, whether the air filter, the intake pipe and the exhaust pipe are blocked, and whether the battery voltage is too low. Whether the electrical wiring of the starter motor is correct, connected, etc. After the above items are all confirmed to be normal, the cause of the failure can be judged based on the fault phenomenon:

1 If the diesel engine cannot start or turn off after starting, the exhaust pipe will not smoke or only a small amount of light smoke, or if the cylinder is compressed well, the exhaust pipe will emit smoke, which is a fault of the fuel supply system.

a. The air in the oil passage can be excluded first. Unscrew the bleed screw on the fuel injection pump and the diesel filter, and pump the oil with the hand oil pump until there is no foam in the diesel oil flowing out from the venting port, then tighten the handle of the hand pump and the bleed screw plug. The Songyu injection pump locks the nut at the high pressure oil pipe at one end of the injector, and rotates the crankshaft. When the diesel oil flowing out of the high pressure oil pipe no longer has foam, retighten the nut . Then turn the crankshaft a few turns to make each injector Filled with diesel.

b. After the air is removed by the above method, if the diesel engine still cannot start, check whether there is air in the oil circuit at the start, that is, whether there is a tight seal at the joint or the tubing is broken. If there is any need to tighten the joint bolt, replace the seal. Pieces or tubing.

C. If it still can't start, loosen the gas screw plug and pump the oil with the hand oil pump. If the diesel oil flows smoothly from the venting port, it means that the diesel pressure is not low, it is generally a malfunction of the fuel injection pump or the injector, which can be separately checked and excluded. If the discharge or diesel fuel is not impeded from flowing out port flows described low pressure diesel failure between the fuel tank and a diesel fine filter, generally within the oil transfer pump failure or blockage. At this time, if the hand resistance is not large when pumping oil, the diesel fine filter oil discharge pipe can be removed, and the pump oil test is continued. If still not feel resistance, the fine filter diesel oil outlet stream is not impeded flow of oil or oil may be fuel pump inlet pipe joint release, smooth flow of the oil to see if there is, if described pump into the oil, the oil valve is closed Not strict, should be ground and repaired. If the vent poor diesel stream, and felt great resistance, you can remove the fine filter diesel pump oil inlet pipe fitting test continues, as the resistance is not felt, and the smooth flow from the tubing at the press start the diesel pump handle, described diesel fine filter clogging, the filter should be cleaned, heteroaryl divisible thereof. If the resistance is still large after the restoration, it indicates that the pipeline between the oil pump and the fuel tank is blocked. The diesel strainer joint can be loosened, the oil is pumped by the hand oil pump, and the oil condition is observed. The blocked part is checked and excluded.

2 If the starting motor speed is low, the starting force is weak, and even the generator cannot be driven to rotate, it is generally a starting system failure. If the electric starting system is wired correctly and the battery power is sufficient, the fault is usually caused by the starter motor and should be checked in time.

3 If you can hear the sound of fuel injection from the injector when starting, but the exhaust pipe only emits white smoke, the crank feels easy, and it is accompanied by the “吱, 吱” leaking sound, it can be judged that the cylinder is compressed. Insufficient pressure. At this time, the cylinder head should be removed for inspection. If the valve is leaking, the valve can be ground to ensure a good seal; if there is a leak between the piston, the piston ring and the cylinder liner, check whether the wear is over-limit and replace or repair if necessary. When the cylinder head gasket leaks, check whether the cylinder head gasket is warped or damaged. If it should be repaired or replaced, pay attention to the thickness of the cylinder head gasket when replacing. Otherwise, the cylinder compression ratio will change. When assembling the cylinder head, tighten the bolts according to the specified torque to ensure the sealing.

4 If it is difficult to start due to low ambient temperature, start the treatment at low temperature.

2. Diesel engine power is insufficient

(1) Symptoms. Under normal load, the diesel engine can not reach the rated speed or the speed is significantly reduced, the operation is unstable, and the sound becomes dull and weak, and it is easy to automatically extinguish.

(2) Analysis of the cause. According to the relevant factors affecting the power of the diesel engine, the reasons for insufficient power are found from the main aspects such as cylinder sealing performance, intake air amount, exhaust volume, and fuel supply.

1 The intake pipe or air filter is clogged and the intake air is insufficient. The exhaust pipe or muffler is charcoal, clogged, and the exhaust is not smooth.

2 The fuel supply system is faulty, including the oil circuit blockage, the fuel does not meet the requirements, the oil pump does not pump oil, the fuel injection pump has a small amount of oil, the injector has insufficient fuel injection, and the atomization is poor.

3 The valve phase is not correct, the time of opening and closing of the intake and exhaust valves is advanced or delayed, the amount of fresh air entering the cylinder is less, and the exhaust gas is not clean, so that the amount of air completely burned by the fuel is insufficient. Fuel injection time is incorrect, the fuel injected into the cylinder of air time too early or too late. Fuel can not completely burned, so that the power drop.

4 Cooling system failure, including blockage of cooling water pipes, insufficient cooling water, poor cooling effect, etc.

5 Lubrication system failures, including lubrication pipe blockage, insufficient oil, and low oil pressure.

6 Cylinder leaks, compression pressure is reduced, fuel burns poorly, and heat energy is reduced.

(3) Treatment method. Check the air cleaner and the intake pipe is blocked, whether the exhaust duct coke, should be blocked if cleaning, clear - If the power is still less than the diesel engine, respectively, check for other reasons.

1 Check if the fuel supply system is faulty. If it is necessary, it should be removed in time to make it work normally.

2 If the exhaust emits black smoke and the exhaust is the least, it is generally a malfunction of the valve train and the intake and exhaust systems. The valve phase and valve clearance should be checked for correctness and the valve spring is damaged . The fuel injection timing is correct. If there is a fault, the relevant parts should be adjusted or replaced to meet the requirements.

3 If the diesel engine overheats, - the general cooling system or lubrication system failure, should check whether the cooling pipe is blocked, the scale in the water jacket is too much, the cooling fan belt is too loose and slippery, the oil cooler is blocked, the oil sump oil Whether the surface is too low, whether the oil pressure is too low, etc., if it is faulty, it should be eliminated in time.

4 When the cylinder is leaking, the cylinder head should be removed and carefully inspected. • Check the valve seal, the wear of the piston, piston ring and cylinder liner , whether the cylinder head gasket is damaged, etc., if necessary, repair or replace it.

3. Diesel engine overheating

(1) Failure phenomenon. The water temperature gauge indicates that the specified value is exceeded, and the diesel engine has a cluttered metal knocking sound when accelerating, and the power is reduced.

(2) Analysis of the cause. The main cause of overheating of the diesel engine is poor cooling or overload operation.

1 cooling system failure

a. The cooling pipe is leaking or the cooling water is insufficient.

b. The cooling fan belt is slack and slippery, and the heat dissipation effect is reduced.

c. The pump is damaged and loses its pumping effect. Air in the pump or in the water pipe forms a gas barrier.

d. Severe fouling or blocked passages in the cooling system.

e. The thermostat is damaged and fails, and the cooling effect of hot water in the body is significantly reduced.

f. The heat sink fins and copper tube surface area are too much, and the winter heat sink is frozen.

2 The cylinder head gasket is broken and the cooling water channel is not smooth.

3 The diesel engine is overloaded for a long time.

(3) Processing method

1 During the operation of the diesel engine, the water temperature gauge indicates that the specified value is exceeded, the cooling water is turned on, and the water overflows from the return pipe. When the engine is accelerating, it will make a messy metal knocking sound, which may easily cause the part to be stuck or broken. It should be stopped immediately. Fill the water tank with water first, check if there is any water leakage. If there is no hand to press the fan belt to check if it is too loose (normally, the belt should be pressed down to 12~20mm) o the belt is normal, then Check the pump water and cooling water pipe unblocked. If the cooling water pipe is seriously fouled or the passage is blocked, it should be washed and dredged in time.

The failure of the thermostat can cause the diesel engine to overheat, which is characterized by the temperature of the cooling water inside the diesel engine being too high, but the temperature of the water in the radiator tank is low. The thermostat may be removed, diesel engine, the diesel engine at this time if the water temperature is normal, it can be concluded thermostat failure, should be repaired or replaced. If the radiator fin and the copper tube surface area are too much, the water tank should be cleaned in time to remove scale and dredge the cooling water channel.

The water tank freeze resistance is more common in diesel engines used in winter. Water heated to about 80 °C can be added to the radiator tank for thawing, and it can also be fired.

2 The cylinder head gasket should be replaced if it is damaged.

After the above inspection, if it is normal, it should be checked whether the oil supply time is too short. Its characteristics are: when the diesel engine is running, the sound is boring and it feels "boom" and the power is insufficient. At this time, the fuel supply advance angle should be adjusted to ensure the correct injection time.

3 If the diesel engine is overheated, if it is caused by overload operation, the load should be reduced immediately.

4. Diesel engine suddenly stops

(1) Symptoms. When the diesel engine is running, it suddenly turns off and stops running.

(2) Analysis of the cause. There are many factors that cause the diesel engine to suddenly stop, mainly considering the fuel and air supply conditions necessary for the operation of the diesel engine. In addition, excessive load can cause sudden stop. The sudden stop phenomenon is often accompanied by faulty factors, and detailed inspection must be carried out, and various faults must be eliminated before restarting the operation. The main causes of the failure are as follows:

â‘  overload operation makes the diesel engine overheating "choke dead."

2 The intake pipe or air filter is clogged and the intake air is insufficient.

3 Fuel supply system failure

a. There is no oil in the fuel tank, and the fuel tank vent is suddenly blocked.

b. Mix water in the fuel.

c. The fuel line is blocked, the tubing is broken or the fitting is loose.

e. The fuel pump plunger is stuck and the spring is broken.

4 gas distribution mechanism failure

a. The valve spring breaks and the valve is stuck in the conduit.

b. The valve clearance is too large or the adjustment screw is loose.

5 The main bearing or the connecting rod bearing burns the tile so that the piston is stuck in the cylinder.

(3) Processing method

1 First check whether the load is too heavy, whether the intake pipe and the air filter are blocked, whether there is oil in the fuel tank, whether the oil circuit is blocked, whether the fuel is mixed with water, and if the diesel engine suddenly stops because of the above reasons, then It should be checked and excluded item by item for other reasons.

2 If the fuel pump plunger is stuck, the plunger or sleeve should be repaired or replaced, and the spring should be replaced if it is broken.

3 If the valve spring breaks in the valve train and the valve is stuck in the pipe, replace the spring and repair or replace the valve and pipe. If the valve clearance is incorrect, re-adjust and tighten the adjusting screw.

4 When the main bearing or connecting rod bearing is burned, the bearing bush should be replaced, and the cause of the burning tile should be found. If the bearing clearance is too small, the lubrication should be eliminated in time to avoid burning the tile again.

5. Diesel engine speed

(1) Failure phenomenon. The so-called speeding refers to the loss of control of the diesel engine speed, which greatly exceeds the specified maximum speed. The main criterion is flying vehicle diesel engine when the sound changes: As the speed increases, the sound (especially the exhaust sound) emitted from a diesel engine and more dense, and even become howling. The phenomenon of flying cars is sudden and will cause serious harm in a very short time.

(2) Analysis of the cause. This phenomenon occurs because the main fuel supply systems should be analyzed, too much supply, transfer speed is the speed limit screw Gao and other changes will result in a sharp increase in speed.

1 Fuel supply system failure

a. The speed governor fly-off is broken, the speed-regulating spring is broken, and the high-speed limit screw changes.

b. The fuel pump rack is stuck at the maximum oil supply position, the rack and the rod are loosely connected, and the rack and gear meshing position is incorrectly installed.

2 Enter a large amount of oil in the combustion chamber

a. There is too much oil in the oil pan.

b. The piston, piston ring and cylinder liner are seriously worn, the oil ring is wrongly installed, and the oil is thrown into the combustion chamber.

(3) Processing method. In the event of a speeding vehicle, emergency measures should be taken to try to stop the diesel engine quickly. The emergency stop method is as follows: First, the oil circuit is cut off, the throttle is pulled to the parking position, and the throttle switch is turned off. However, most of the reasons for the speeding of the car are that the throttle loses control of the oil pump plunger and there is still oil in the low pressure oil circuit. This kind of measure often does not stop the diesel engine quickly. „If the high pressure oil pipe connection nut is unscrewed, the diesel engine is immediately “Oil cut off”, in most cases, it can stop quickly; second, cut off the gas path. For small diesel engines, the intake pipe is small, and the air filter can be directly wrapped with cotton or the like, or the air filter can be quickly Remove and directly block the air inlet. In any case, as long as the intake passage is blocked, it can be stopped quickly.

In short, according to the different structures of various models, all measures can be taken to quickly cut off the oil circuit and the gas path, so as to avoid accidents caused by the flying car. It should be specially pointed out that after the failure of the flying car, it is absolutely forbidden to reduce or remove the load, which will cause the diesel engine speed to rise sharply and the damage is even greater. After parking, the cause of the flying car should be analyzed and eliminated in time to avoid the recurrence of the flying phenomenon.

1 When the throttle is cut off, the speed of the diesel engine is reduced or turned off, which is mostly a governor failure . After the parking, the governor cover should be removed for detailed inspection. When the flyweights be reassembled off, the spring rupture should be replaced, Gao limit screw speed changes readjust, the governor may be detached for repair if necessary.

2 If the fuel injection pump is faulty, it should be inspected in detail, find out the cause, re-adjust the assembly, replace some parts if necessary, or remove the fuel injection pump for repair.

3 If the oil sump oil is too much, it should be reduced. The piston, piston ring and cylinder liner are seriously worn, and should be replaced and repaired.

6. Diesel engine cooling water tank freeze resistance

(1) Symptoms. The cooling water does not circulate and the diesel engine overheats.

(2) Analysis of the cause. The cooling block of the cooling water tank occurs mostly in the cold winter in the north. There are several reasons: the diesel engine lacks water during winter operation; the cooling water tank has too much fouling, and the cooling water circulation is not smooth; in winter, the diesel engine is parked outdoors for a long time, cooling The water freezes.

(3) Treatment method. When observing the water temperature gauge, the indication exceeds the specified value. The hand touches the water tank and feels the ice hand, indicating the freezing resistance of the water tank; the water tank is touched by hand, the upper water chamber feels hot, and the water chamber feels the ice hand, which also indicates that the water tank has a freezing resistance; Open the steam hood of the water tank. If there is boiling hot air, it means that the cooling water does not circulate, and the water tank has a freezing resistance.

The most vulnerable part of the cooling system is the junction of the water tank and the pump and the center of the tank. When the freezing resistance occurs, it can be baked by fire; you can also pour hot water of about 80 °C into the water tank, and then drop it again after a few minutes. After a period of time, the fault can be eliminated. At this time, you should pay attention to the cause of the freezing resistance, so as to prevent the fault from happening again.

Measures to prevent the freezing resistance of the water tank include: the lack of cooling water in the winter operation of the diesel engine should be added in time, and it is best to add antifreeze in the cooling water; when there is too much fouling in the cooling water tank, the water tank should be shut down to remove the scale and ensure the smooth circulation of the cooling water. The cooling radiator has good heat dissipation; if the diesel engine is parked outdoors for a long time in winter, the hot water of 60~80 °C should be poured into the water tank before starting the machine. When the temperature of the cooling water rises, the diesel engine can be started up after warming up.

7. Diesel engine exhausts black smoke

(1) Symptoms. When the diesel engine is running under load, the exhaust is generally light gray, and when the load is slightly heavy, it may be dark gray. If the exhaust is black, it is a malfunction.

(2) Analysis of the cause. Exhaust black smoke is generally caused by excessive combustion of diesel fuel in the combustion chamber , and diesel combustion is not completely caused. Therefore, exhausting black smoke is a sign of poor combustion. Sometimes, because of channeling the oil into the cylinder, the combustion exhaust gas may also produce black smoke emission. The main reasons for exhausting black smoke are:

1 The load is too heavy, so that the oil supply is too much, causing the diesel to burn incompletely.

2 The air filter or intake pipe is blocked, the air volume in the cylinder is insufficient, and the diesel combustion is incomplete.

3 Fuel supply system failure, the common quality of diesel is poor, the fuel injection pump is too early, too late, the fuel injection is too large, the injector is poorly atomized or dripping.

4 The valve clearance is incorrect and the valve sealing cone is not in good contact.

5 The oil pan has too much oil, and the oil ring is wrongly installed or worn, causing the oil to enter the cylinder to burn.

(3) Processing method

1 Check if the diesel load exceeds its rated power. If it exceeds the load, reduce the load.

2 Check if the air filter and the intake pipe are blocked. If it is blocked, it should be dredged. Check that the quality of the diesel oil meets the requirements. If it does not meet the requirements, it should be replaced.

3 If there are too many fuel injections in individual cylinders, it can be checked by stopping the fuel injection by cylinder. The fuel injection of a certain cylinder is stopped, so that no black smoke is generated, and there is no change or little change in the operation of the diesel engine, indicating that the injector of the cylinder is faulty or the fuel injection amount of the fuel injection pump is too large. The side cover of the fuel injection pump can be removed, and it is checked whether the locking screw of the adjustment gear of the cylinder is loose and the fuel injection amount is excessive. If it is intact, the sentence will be sprayed off the oil, connected to the high-pressure oil pipe of the cylinder, and then use a screwdriver to smash the plunger spring seat, in exchange for the pump oil action, check the injector fuel injection. If the fuel injection of the injector is not atomized or the atomization is poor and the oil is dripped, the injector should be decomposed and checked.

After a single cylinder inspection, if it is found that the general fuel injection amount is too large, the governor cover should be opened to check whether the tangential line of the adjustment toothed rod is moved too much into the fuel injection pump casing (the scribe line should be parallel to the fuel injection pump casing). It can be seen outside, and at the same time, check if there is any stuck in the governor flyweight, etc., causing excessive fuel injection.

After the above inspection, if no fault is found , the fastening screw of the fuel pump connection plate can be loosened, and the connection plate can be rotated to delay the injection time slowly. If the black smoke disappears, the diesel engine does not shake, indicating that the injection time is too early. Check if the injection time is out of alignment. If these parts are inspected, it is good . Check whether the timing adjustment screw on the plunger of the fuel pump plunger is suitable. If it is not suitable, it should be re-adjusted.

4 If the valve clearance is not correct, the valve seal cone contact is bad, causing the exhaust to emit black smoke. The valve clearance should be adjusted to the standard value, or the valve should be ground or replaced to ensure a good seal.

5 If there is too much oil in the oil pan, it should be reduced to the specified height. If the oil ring is installed incorrectly, it should be reinstalled. If the oil ring is worn out seriously, it should be replaced.

8. Diesel engine exhausts white smoke

(1) Symptoms. Diesel engine exhaust emits white smoke, and diesel and cooling water consumption increases.

(2) Analysis of the cause. The exhaust gas is grayish white and has a very strong diesel smell. Most of them are incompletely burnt due to poor atomization of the diesel, and white smoke is discharged.

1 Diesel engine temperature is too low, diesel is not easy to burn.

2 The diesel fuel is mixed with water, and the water is heated in the cylinder to be discharged from the exhaust pipe.

3 The fuel injection time of the fuel injection pump is too late, the temperature inside the cylinder drops, and some unburned diesel oil is discharged from the exhaust pipe by white mist.

4 Injector has low injection pressure, poor injection atomization or dripping oil, so that diesel oil is not exhausted.

(3) Processing method

1 If the temperature of the diesel engine is too low (especially in winter), a hot water heater of 60~80 °C can be used. If possible, the cooling water or oil preheating device should be added to ensure that the temperature of the diesel engine is not too low. After warming up or running for a period of time, if the temperature is too low, the phenomenon of exhausting white smoke will generally disappear.

â‘¡ After a period of operation the diesel engine, if the exhaust gas still take white smoke due to low body that failure is not caused by temperature, should look for the other reasons. If the water is mixed into the diesel oil, it will cause white smoke in the exhaust. Check whether the cylinder head gasket is damaged or not, and the bottom surface of the cylinder head is cracked to cause drowning. Repair or replace the cylinder head if the cylinder head gasket should be replaced. If the diesel contains water, the diesel should be replaced.

3 When the exhaust is white smoke, the diesel engine is weak, overheated, and there is a low knocking sound. First, check the fastening of the fixing screw of the fuel pump splicing plate and the connection of the key to the keyway. Loosen the fixing screws of the connecting plate and slowly inject the oil in advance. If the white smoke phenomenon is improved or even eliminated, the diesel engine runs normally, indicating that the injection time is too late and can be adjusted slowly to meet the requirements. If the white smoke phenomenon does not improve, check whether the timing adjustment screw of each plunger of the fuel injection pump is out of adjustment. If the imbalance is adjusted, it should be adjusted to meet the requirements.

4 Injector is poorly atomized and can be inspected by stopping the single cylinder oil supply. After finding the suspect cylinder, remove the injector of the cylinder and perform the fuel injection test. If the oil is dripped during fuel injection, it should be checked whether the injection pressure is too low, or the needle valve body is deformed or worn, and should be adjusted or repaired or replaced if necessary.

9. Diesel engine exhaust blue smoke

(1) Symptoms. The diesel engine exhausts blue smoke and consumes the most oil.

(2) Analysis of the cause. Blue smoke is generally the result of a large amount of oil entering the cylinder and not being burned out (if the oil burns, it will emit black smoke). Blue smoke failure should mainly be based on the leakage of oil into the cylinder.

1 There is too much oil in the oil pan, the oil level of the wet air filter is too high, and the oil pressure is too high.

2 The oil returning to the cylinder head is not smooth, and it leaks into the cylinder along the valve stem.

3 The cylinder, the piston and the piston ring are seriously worn, the clearance is too large, and the piston ring is incorrectly installed, so that the oil enters the cylinder.

(3) Processing method

1 Check if there is too much oil in the oil pan and air filter oil, if the oil pressure is too high, if it should reduce the oil level, adjust the oil pressure. If the fault has not been eliminated, you can check it separately as follows.

2 The oil pipeline is clogged, especially if the oil return is not smooth at the cylinder head. The oil passage should be unblocked and cleaned in time to ensure smooth oil return.

â‘¢ The blue smoke at the same time with diesel power shortage, it may be determined wear of the piston ring, or between the cylinder and the piston between the gap is too large, or piston rings installed wrong, should be reinstalled or replacement of piston rings, cylinder liners or replacement With the piston.

10. Diesel piston knocking

(1) Failure phenomenon

1 Piston knocking sound is obvious when idling, it is the sound of "嘡, 嘡", and the sound of the connecting rod bearing is close. It can be determined according to the temperature change of the diesel engine: when the cold machine is louder, the heat machine is lighter or disappears, and when the throttle is suddenly increased, it becomes a "beep, bang" knocking sound, which is the piston knocking sound.

2 Multiple cylinder piston knocking sounds, from idle speed to medium speed or high speed, the sound becomes messy.

3 When the diesel engine is running at high temperature and high speed, continuous "嘎, 嘎, 嘎 " impact sounds appear , and a cylinder is broken, and the sound will not be weakened or disappeared.

(2) Analysis of the cause. The piston knocking sound is mainly caused by the friction and impact of the piston with the cylinder wall and the valve.

1 The clearance between the piston and the cylinder wall is too large.

2 The top of the piston hits the cylinder head gasket or cylinder head, or the piston hits the valve.

3 The piston is deformed by heat, and the gap with the cylinder wall is uneven, and the friction increases.

4The piston skirt is worn seriously or the cylinder is out of round .

5 The connecting rod is bent and twisted, or the connecting rod bearing bush and the piston pin bushing are too tightly matched, so that the piston generates a sound when the cylinder is moved unevenly.

(3) Processing method

1 The clearance between the piston and the cylinder wall is too large, so you can check the degree of wear and repair and replace if necessary.

2 The sound of the piston top cylinder head is often seen when the diesel engine is running at an idle speed, and it is more serious, and can be heard at low speed. When the throttle, heard a rapid, continuous and crisp "despair, despair, despair" contradict sound "may come into contact with the cylinder head screwdriver cylinder head, the vibration of the case by checking at if they feel there is somewhere Vibration, it can be preliminarily determined that the top of the piston hits the cylinder head. This kind of knocking sound is a vicious sound, which should be eliminated in time. When removing, the cylinder head can be removed to check the top touch marks and deal with it according to the specific situation. Top touch . The top of the piston can be slightly removed and can still be used.

The method of checking the piston flapping sound is the same as that of the piston top cylinder head. If the noise does not vary with the piston portion moves. And the inter-ring to remove the valve chamber cover, a touch on the screwdriver valve rocker arm, the rocker arm or Yong Shounie check valve, such as vibration somewhere valve rocker shaft, and Obviously feel that the valve rocker hits the hand, it can be preliminarily concluded that the valve is in contact with the top of the piston, and should be eliminated in time. After inspection and testing, if the timing gear is found to be wrong, it should be newly installed. If the valve clearance is too small, it should be re-adjusted.

3 When the diesel engine is running at high temperature and high speed, continuous "嘎, 嘎, 嘎" impact sounds appear . The screwdriver can be touched on the cylinder head and in the middle of the cylinder block to check it one by one. If the sound heard on the cylinder head is obvious and feels vibration, the screwdriver can be further touched on the cylinder head and checked by hand for vibration. If there is no obvious vibration, it means that the piston does not hit the cylinder head, but the piston strikes the cylinder head longitudinally. The cylinder head can be removed, the crankshaft is rotated to raise and lower the piston, the longitudinal swing of the piston head at the upper and lower dead center positions is observed, and the presence or absence of a strike mark on the cylinder wall is checked. In the case of a piston swing, the piston rod set can be withdrawn, or the diesel engine can be decomposed for detailed inspection, and if necessary, the piston, cylinder liner or connecting rod assembly can be replaced.

â‘£ the screwdriver in contact on both sides of the upper portion of the cylinder block, at the front by auscultation, hair ring around the cylinder, and slightly stronger sound vibration, combined with the fuel cut test can determine which cylinder hair ring. Pistons with excessively tapered skirts tend to present "anti-upper cylinders" (disconnecting a cylinder, the sound is enhanced) and change from a loud to a continuous sound. In order to further confirm, the diesel engine can be cut off from the oil, the injector is removed, a small amount of oil is poured into the cylinder, and the injector is installed to start the diesel engine inspection. If the sound is weakened or disappeared, after a while there will be a loud sound, or a few sounds will appear within a few tens of seconds after the fire, then disappear, and after a while there will be a sound, then it can be concluded that the cylinder is knocking. Such a sound only occurs when the diesel engine is at a low temperature, and disappears after the temperature rises, and can not be excluded. When it is diagnosed that it needs to be removed, the cylinder head can be removed, the cylinder wall of the sounding cylinder is checked for damage, and the lubrication condition is good. Then the piston connecting rod set is taken out, and then the piston is inspected for damage, burning and knocking. Traces and measure cylinder and piston clearance . If the clearance exceeds the specified or the piston is out of standard, the piston ring or piston should be replaced. If the splash lubrication is insufficient, the lubricating oil circuit can be inspected in detail to ensure the lubrication effect.

5 The connecting rod should be bent or twisted to be repaired or replaced. If the bearing bush or bushing is too tight, it should be scraped or replaced to ensure flexible rotation between the piston pin and the bushing, the connecting rod bearing bush and the crankshaft.

11. Diesel spindle bearing knocking sound

(1) Failure phenomenon. This is a heavy, boring " beep, bang" knocking sound, the higher the speed of the diesel engine, the louder the sound. When suddenly increase the throttle sounds more prominent, the occurrence of a large diesel engine vibration shaking. Sudden heavy "tum tum tum" sound when you drop speed. When the diesel engine has a load, the sound is more obvious, and the sound does not change when the temperature changes.

(2) Analysis of the cause. The knocking sound of the main shaft bearing is mainly caused by the radial direction of the bearing, the excessive axial clearance, and the bending of the crankshaft.

1 The bearing cap fixing screw is loose.

Liquid Silicone Rubber Injection Machine

The liquid silicone rubber injection molding machine is fully computer controlled, with accurate measurement and uniform mixing; it adopts static mixer static pressure injection method, equipped with hydraulic or air control nozzles, manifold, injection pipe and nozzles are equipped with cooling water channels; easy to clean Simple, reducing manpower and material waste.

Liquid Silicone Rubber Injection Machine,Liquid Injection Machine,Silicone Injection Equipment

Changzhou Yuehai Zanyang Machinery Sales Co., Ltd. , https://www.zanyangmachine.com