3.1 difficulties in starting a Marine diesel engine.

1. Fault phenomena

When the starting difficulties are found, there are several situations:

When starting, the crankshaft does not move or turn very slowly, that is, the starting speed is too low.
 

The starting speed is normal, but the diesel engine does not catch fire.
 

When the ship started, the ship's diesel engine was on fire, but the diesel engine was not working properly, the speed was unstable, and even the fire was put out.
      

2. Cause analysis

Starting system: the leakage of the trachea or the trachea is too long, the air source pressure is insufficient, the air compressor is damaged, etc.
 

2 fuel system: low oil pressure parking lever not board, the fuel tank valve does not open, no oil fuel tank, fuel tank position is too low, fuel line with air, diesel filter was too dirty, speeding parking equipment is not reset, rack stuck not come on, don't spray injector, fuel pump pump oil or fuel injector fuel injection.
 

The air filter is fouled, the middle cooler is fouled, the valve of explosion-proof door is not open, the gas timing is not correct, and the exhaust system is fouled.
 

The combustion system: the compression pressure is insufficient, the piston and the cylinder cover are too large and too small, the cylinder head is too large and too small.
 

External conditions: starting with load, the oil temperature is too low and the viscosity is too high;
The water temperature is too low to freeze in the water pump;
The diesel temperature is too low and the viscosity is too high.
 

Internal conditions: the valve can touch the piston or the cylinder has foreign body;
Burn tile, hold shaft, pull cylinder.
 

3.2 insufficient power of ship diesel engine.

1. The failure phenomenon is called insufficient power, which is commonly referred to as the "powerlessness" of Marine diesel engines and "no strength".
Normally, the power of Marine diesel engine has certain reserve, which can drive the working machine to operate normally.
When the power is not enough, the performance of the Marine diesel engine with the supporting work mechanical movement, and with the following phenomena.

The ship diesel engines smoke black smoke.
At this time the ship diesel exhaust pipe discharged a large amount of black smoke.
High exhaust temperature of ship diesel engine.
At this point the exhaust pipe and turbocharger's turbine is dark red.
The ship's diesel engine speed is down or the rotating speed is unstable, and it shows the sound of weak work.
2. Reason analysis: the oil supply is insufficient: the fuel filter is clogged;
The fuel line is too thin and too long to leak;
The fuel system has air;
Poor quality of fuel, water in oil;
Oil injection pump or regulator limit lead seal is damaged without oil;
The governor pull rod screw is too much, the tooth stick out length is not enough;
The pump plunger wear seriously individual cylinder oil supply is too small.
 

Bad atomization or mismatch with the combustion chamber: the oil head is atomized;
The oil supply advance Angle is not correct;
The head of the oil is out of the cylinder.
Cylinder head piston coals are serious;
The compression gap is too large;
The outlet valve is not tightly sealed.
 

Insufficient air intake: air filter dirty;
The dirty of the cooler;
Air compressor impeller dirty;
The cylinder cover inlet is dirty;
Air leakage in the exhaust pipe;
Air timing is not allowed;
Supercharger failure, low inlet pressure.

Poor exhaust: the exhaust pipe is too curved or too long;
The exhaust muffler is dirty;
The cylinder cover exhaust duct is dirty;
The exhaust timing is not correct.
 

External factors: the water inlet temperature of the middle cooler is too high;
High ambient temperature and high humidity;
High altitude and low pressure;
Marine diesel engine overheating;
Abnormal wear, Marine diesel engine cylinder, burning, holding shaft, etc.
 

3.3 the speed of Marine diesel engine is not stable.

1. When the Marine diesel engine is in normal operation, it depends on the automatic regulating effect of the governor, and the rotating speed of the Marine diesel engine is stable.
The fluctuation value is only a few turns, the fluctuation rate is within 0.5%.
When the speed is unstable, there are two phenomena:

The ship diesel engine has a regular high and low.
What is commonly referred to as a "coach", "breathing".
This kind of situation occurs mostly in the low speed operation condition of Marine diesel engine.
 

The speed of the diesel engine is erratic and erratic.
 

2. Reasons for the instability of Marine diesel engines are as follows:

The reason of the oil supply system: there is air in the fuel system, water, gas resistance or water resistance, causing the oil supply to be unstable;
The injector atomizer is not good, spray oil is not stable, oil spray, or intermittent spray oil;
Oil pump plunger outlet valve wear too large, oil supply instability;
The rack of the fuel injection pump is stuck, and the injector pin valve is stuck.
Sprayer spring, oil valve spring, oil injection pump spring break;
Adjusting gear ring for oil injection pump;
The oil supply of each cylinder is seriously uneven.
 

The reason of the speed regulation system: there is too much oil in the governor.
The governor spring deformation, fracture or stiffness decrease;
The governor flying iron considers to wear serious wear;
The governor motion is stuck or badly worn.
 

For external reasons: the ship diesel engine with gearbox is defective and skidded;
The mechanical load of the work is seriously unstable.
 

3.4 ship diesel engines.

1. Under the control of the governor, the speed of the ship's diesel engine is stable at a certain working condition.
Even when the working mechanical process is fully loaded, the engine speed of the Marine diesel engine will not be too high, which can only be more than 8% of the speed before unloading.
When a "flying car" occurs, it means that the ship's diesel engine is out of control and its speed increases rapidly, exceeding the calibration speed.
This is accompanied by the following phenomena:

An abnormal sound.
Because of the speed bump, the combustion noise, air noise and mechanical noise of Marine diesel engines are increasing rapidly, which is even unbearable.
 

The vibration is abnormal.
Due to the increase of speed, the imbalance of inertial force of Marine diesel engine is greatly increased, so the vibration of Marine diesel engine increases sharply.
 

It is often accompanied by damage to the machine.
 

2. Cause analysis

The first is the failure of the fuel system to control the governor control system.
Second, the governor control system fails.

In summary, the reasons are as follows:

Oil fuel system: the injection pump plunger is dead in the oil quantity position;
The rack of the fuel injection pump dies in the oil quantity position;
The rack of the fuel injection pump is loose or laminated.
The spring break of the oil injection pump, the tooth ring card holder;
Misloading the plunger of the injection pump;
The screw seal on the rack is open.
 

The speed regulating system: the governor moving parts are stuck;
Speed regulating spring break;
Loose iron loose;
The oil temperature is too low and the viscosity is too high.
 

Other factors: the cylinder head oil return oil hole is not smooth, the lubricating oil enters the combustion chamber;
The speed automatic stop device fails;
On the rack, the parking card block and the oil pressure low parking fork position are wrong, the rack is in the refueling position.
 

The ship's diesel engine stopped suddenly.

1. When there is a sudden stop, there are two situations.
One is to stop running suddenly, one is to slow down, and then stop.
 

2. Cause analysis

Fuel system: the fuel tank is used up;
There is water in the fuel, air;
Blockage of fuel system;
Failure of fuel line;
The plunger of the injection pump or the oil valve sticking;
Nozzle needle valve stuck;
The governor spring breaks and the rack automatically returns to the stop position.
 

The system: the valve card main or valve spring break can not be replaced properly;
Incorrect timing of gear damage or injection;
Damage to the driving device of the fuel injection pump.
 

The fault of the moving parts: the cylinder and the cylinder of the ship's diesel engine;
Marine diesel engine burning, holding shaft.
 

Safety protection system: oil pressure low automatic stop device plays a role;
The speed automatic stop device works;
Explosion-proof door is closed automatically.
 

Other factors: the external load suddenly increases, the ship diesel engine is suffocated.
 

3.6 vibration anomaly

1. Due to the stress and inertia force of the ship diesel engine, it is normal to produce certain vibration.
When the working condition is certain, its vibration size and law are certain.

In case of abnormal vibration, the following phenomena are often observed:

The vibration of each part of ship diesel engine is increased.
Especially the parts such as the high-pressure oil pipe, the middle cooler, the governor, etc., can see the vibration with the naked eye, and feel the numbness with the touch of the hand.
With the exception of vibration, it is often accompanied by abnormal sound.
2. Reason analysis: the work of each cylinder is not balanced: the oil supply quantity of each cylinder is unbalanced;
Imbalance of oil supply Angle of each cylinder;
Cylinder compression ratio imbalance.
 

The inertia force is unbalanced: the quality error of each cylinder piston connecting rod group is too large;
The crankshaft dynamic balance error is too large, or crankshaft bending deformation;
Flywheel balance is extremely poor;
Supercharger rotor dynamic balance, or impeller damage;
The balance shaft gear assembly position is wrong;
Failure of shock absorber;
The bearing clearance is too large.
The installation foundation and the working machine pair: the installation foundation is weak and the stiffness is poor;
Insufficient foundation stiffness;
Install screw loose;
Marine diesel engine and working machinery to neutral difference.
3.7 the reason of high exhaust temperature is too high. It is mainly caused by combustion system, fuel system and intake and exhaust system.
The exhaust temperature of the diesel engine is the temperature of the exhaust gas from the diesel engine.
Normal exhaust temperature depends on the normal combustion of Marine diesel engines.
The basic condition of normal combustion is that there is a certain amount of fuel, which is well mixed with enough air under the condition of good atomization, and completely burns in the combustion chamber.
Therefore, the factors that do not meet these conditions will cause the exhaust temperature to be too high.
1. Intake and exhaust system: the air inlet resistance is large: the air filter is dirty, the air compressor is dirty, the cooler is dirty, and the cylinder head is dirty.
Low inlet pressure: failure of supercharger;
Air leakage in the exhaust pipe.
 

The exhaust resistance is large: the exhaust pipe is too thin and too long.
The cylinder cover exhaust pipe fouling.
 

There is no gap between the two valves.
 

2. Fuel combustion system: the oil supply is too late;
Individual cylinder oil supply is too large;
Bad atomization of fuel injector;
Poor fuel quality, not meet the requirements;
Cylinder compression pressure is low.
 

3. Others: the ambient temperature is too high;
Cold water temperature is too high;
Overload.
 

3.7 ship diesel engine abnormal color ship diesel engine work normally, the exhaust fumes are light gray, is just a black smoke, occurs on accelerating so when abnormal color, have the following phenomena:

It's a black smoke.
This is a feature of the incomplete combustion of a ship's diesel engine, which has a large number of solid particles in the exhaust gas, and sometimes even Mars, with an increase in the exhaust temperature.
 

It was a white smoke.
This is the characteristic of water or fuel vapor in diesel exhaust.
At this time, the exhaust gas from the ship diesel engine is white fog, accompanied by the loss of power of the diesel engine and the instability of the speed.
 

It's like blue smoke.
This is the characteristic of a large amount of oil vapor in the exhaust gas.
It is accompanied by an increase in the consumption of smoke and diesel oil.