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Failure analysis of diesel engine power shortage

Pubdate:2015-12-14 20:16  Source:New  Author:New
Surprisingly strong new-vehicle sales in August, the best since 2003, have renewed speculation about whether suppliers finally will start an expansion binge to keep up with ever-increasing vehicle production. According to WardsAutos latest
After long-running diesel engine, because the parts are worn or operation, improper adjustment, maintenance is not timely and other reasons, often have the problem of insufficient power. Diesel power shortage causes more complicated, but there are two main reasons: First, because the combustion chamber seal bad, insufficient fuel supply, bad injector atomization, insufficient amount of gas, oil and other reasons improper timing adjustment , resulting in incomplete combustion of fuel, diesel leads to lack of motivation; the second is due to mechanical wear and tear is too large, poor lubrication, poor cooling, improper installation and other reasons, the diesel engine itself caused friction loss power is too large, the output power is reduced, leading to diesel power shortage. Therefore, when analyzing the lack of diesel power failures excluded, should seize the friction losses and the size of the combustion quality of two key issues which, combined with the operation and user understanding of the wear state of the art diesel engine parts and master, so look for the most likely cause of the shortage of diesel power for several reasons, then checked and ruled out. Diesel underpowered reasons:
 
First, the intake and exhaust system is not smooth
 
Engine air filter and intake due to the excessive dust does not flow or blockage, will make less than the amount of air entering the cylinder, not only lead to insufficient compression pressure, but due to lack of fuel and not enough air for complete combustion, resulting in Diesel power shortage. Under other conditions normal circumstances, if the exhaust pipe or muffler lot of carbon, the exhaust is not smooth, so that the cylinder exhaust exclude clean, it will result in reducing the amount of fresh air entering the cylinder. In this case, although the compression pressure is not low, but the amount of air entering the cylinder is insufficient, but also make the fuel is not completely burned, resulting in shortage of diesel power and black smoke. Therefore, the user should periodically remove the air filter and intake of dust, periodically clear the exhaust pipe and muffler soot and dirt, to ensure the smooth flow of intake and exhaust systems.
 
Second, the intake and exhaust system is not sealed
 
Turbocharged diesel engine exhaust pressure by blowing the turbine wheel so as to drive the high-speed rotary pumps, compressed air into the intake pipeline, thus ensuring greater power output diesel. Therefore, turbocharged diesel engine intake and exhaust system must be completely sealed. Exhaust pipe or fittings if leaks, exhaust pressure is reduced turbocharger speed decreases, the intake pressure decreases, causing diesel power down. Intake system (including intake, intercooler and all joints) if leaking, so although the intake pressure turbocharger provides a standard, but the real amount of air entering the cylinder will be significantly less than that of diesel engine power down. This failure often occurs after repair and maintenance, especially re-assembled into, after the exhaust system, due to various reasons Mifengbuyan situation.
 
Third, the lack of pressure within the cylinder compression
 
Diesel fuel injector mounting hole leaks or copper pad damage, cylinder head gasket leak, valves, valve seats, cylinder liners, piston, piston ring wear is too large, the valve clearance is too small, the gap is too small pressure-reducing mechanism and other reasons, will sealed combustion chamber causing poor fresh air entering the cylinder to leak out from these areas, resulting in insufficient amount of air within the cylinder, the fuel can not get enough air in the combustion chamber can not be completely combusted, natural reduce engine power, leads to lack of motivation. At the same time, due to insufficient amount of air within the cylinder, the compression end pressure and temperature to be reduced and the combustion process of fuel postponed, after combustion phenomena caused, so that part of the fuel with the combustion exhaust gas a chance to fully discharge. In addition, the high pressure gas will leak out from the site, so that the gas acting ability is reduced, resulting in shortage of diesel power. Another feature of diesel power shortage has shown that black smoke. Thus, the pressure within the cylinder compression diesel shortage is one of the main causes of power shortage, the event should be promptly removed.
 
Fourth, poor turbocharger
 
The turbocharger is a key component affecting diesel powered. If the booster burnout will result in reducing its speed, the intake boost pressure drops, resulting in reduced diesel power. Early signs of turbocharger damage is "drain" is to the exhaust duct and the air intake duct discharge of oil, expressed turbocharger has become corrupted when severe drain. Turbocharger rotor axial and radial clearance must be guaranteed within a predetermined range. Diesel engine equipped with a supercharger in use should be noted that a few minutes after starting the need to idle, standby oil have been circulating after the acceleration and processing load, especially should pay attention to the initial start every day. The same should be idling diesel engine flameout few minutes, until the diesel engine and turbocharger speed drops after the line stall. Turn off the habit before Meng throttle operation, the turbocharger life is a fatal blow, because the flame front feet Meng throttle, supercharger speed increase immediately, when the diesel engine suddenly stalled, oil pump stops running and stop oil supply, but in the turbocharger lubrication harsh conditions to continue its rapid rotation of dry grinding, the rotor shaft and bearing accelerated wear of the seal ring strain and drain, the turbine will be severe burning, broken rotor shaft.
 
Fifth, the timing of fuel injection pump oil inappropriate
 
Because diesel fuel pump injection timing adjustment improperly, fuel pump wear is too large and other reasons, it will cause the fuel pump injection timing is too late, and thus the entire combustion process is postponed, commonly referred to as "post-combustion." In this case, part of the oil will be discharged too late to complete combustion cylinder, the fuel and energy are not fully utilized, resulting in shortage of diesel power, resulting diesel black smoke, heat parts, exhaust temperature is too high, serious exhaust pipe will sparkle and so on. At this point, you should check and when the injection timing adjustment. If the plunger deputy, deputy oil valve wear too much, should be repaired or replaced.
 
Sixth, poor performance Injector
 
Diesel injector needle jamming, clogging spray or fragmentation, injector spring break or elastic disappear, injector spring adjustment too tight or too loose, the plunger deputy, deputy oil valve, needle deputy wear too large, low pressure oil fuel system blockage and other reasons, will cause bad injector atomization or dripping, etc., so that incomplete combustion of fuel, leading to diesel power down. At this point, the main features of diesel is black smoke, should be repaired or replaced.
 
Seven, fuel system supply shortage
 
Fuel system problem of inadequate supply of "blocking" and "leakage" two aspects. The so-called "blocking" is due to the long-term maintenance, resulting in clogged fuel filter and piping dirt section, so that the oil resistance increases, fuel poor. If the engine load is less in the case of a small amount of oil, the fuel supply is also able to meet the requirement, but under heavy load large amount of oil, the fuel supply can not meet the requirements, 'resulting in decreased diesel power. Therefore, in order to ensure the smooth flow of oil supply system must be maintained according to regulations. Low oil called "leakage" is from the tank to the pump for leaks. Similarly, in the case of small load less oil supply enough oil in a large amount of oil under heavy load conditions, due to the low-pressure oil passage intake air leak, resulting in insufficient fuel supply, resulting in shortage of diesel power failure. "Leakage" often appear after the repair and maintenance, fuel filter and piping disassembly in maintenance, if the joint Mifengbuyan or filters installed strict closure seals during assembly, it will cause "leakage" fault.
 
At the same time, fuel pump or a valve plunger deputy vice excessive wear, spray clogging needle catching other reasons, the insufficient amount of oil fuel pump can not meet the requirements of the engine load increases, it can lead to diesel underpowered. The resulting lack of power, will not cause damage to the diesel engine parts, diesel engine user will feel powerless, speed can not be improved, lower temperature and exhaust gas temperature heating parts. Found such a case, you should check the cause of the oil shortage, and remove.
 
Eight working poor governor
 
Diesel governor adjustment due to improper assembly, governor spring too tight or broken, deflation and other reasons, the governor injection pump rack movement pushing force is too small, causing the fuel pump is difficult to increase the amount of oil, It will result in shortage of diesel power. In this case, the diesel engine is characterized by accelerated significantly more difficult, slow speed increases; reduction easier, faster speed is reduced, and the rotational speed of the diesel engine is unstable. You should check, adjust or replace governor spring. In addition, if the power of the diesel engine did not change significantly, but viewed from the dashboard tachometer maximum speed falters, then the generator is generally caused by loose belt. Because some diesel generator tachometer are connected by wires to the way the tachometer, the detected rotational speed of the generator, after conversion of the pulley ratio, engine speed indicated on the instrument. Thus the belt slack, will cause the engine speed indication errors. This failure appears not to be mistaken for lack of engine power failure, the generator belt tightening, the fault will be solved. When servicing the generator assembly needs to be replaced, the replacement should be noted that the new alternator pulley diameter should be the same as the old generator, or will cause the engine speed indication errors illusion.
 
Nine, poor lubrication and cooling system
 
Engine lubrication system due to a malfunction, resulting in insufficient quantity or interruption of oil, oil is too dirty, the gap is too large or too small, diesel engine overheating and other reasons, so that the relative movement of parts of poor lubrication, friction loss of power will increase, resulting in decreased output power diesel engine, the diesel engine when the accident occurs bush-burning or pulling cylinder, friction loss power increases rapidly, drastically reducing the power output of the diesel engine, the diesel engine can cause severe self parking. Due to poor lubrication caused by lack of diesel power, there are several distinct characteristics. That diesel engine parts heating, oil temperature, severe can smell the burnt smell of oil, diesel emit abnormal sounds dull. At this time should be reduced or lifted load diesel engine, making it empty running at low speed, in order to find the reason for exclusion. Also, if too much oil in the crankcase, the oil so that the oil is too high, the resistance movement of the crank linkage mechanism increases, the power consumption increases, will result in shortage of diesel power.
 
In addition, the diesel engine is too large due to the overload, the running time is too long, insufficient coolant flow or interruption of other factors, the diesel engine operating temperature is too high, it will reduce the amount of air entering the cylinder, causing the fuel is not completely burned, the power of the diesel engine reduced, resulting in lack of motivation. When the engine temperature is too high, you should check the radiator and piping, remove scale.
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