If you have Cummins diesel power
generator, maybe you meet some problems in its diesel engine.
1.Why diesel engine starts up more
difficult in winter?
Start-up of diesel engine, not only
depends on itself technical situation, but also is influenced by ambient
air temperature. Here is the reason as follows:
A.In winter, the climate is cold, the
ambient temperature is low, the oil viscosity increases, and the friction
resistance of the moving parts increases, which reduces the starting speed and
makes it difficult to start;
B.The capacity of storage battery decreases with the decrease of
temperature, which further reduces the starting speed;
C.Because of low speed of start-up,
leakage of compressed air increasing and heat dissipation of cylinder wall
increasing, the temperature and pressure of air at the end of compression are
greatly reduced, and the delay period of diesel ignition is increased, even if
it is serious, it can not be burned;
D.Diesel oil viscosity increases in low
temperature, so that injection velocity speed decreases, and at the end of air
compression, the whirlwind speed, temperature and pressure of air are
relatively low, which makes the quality of diesel fuel injected into the
cylinder poor. It is difficult to form a good combustible gas with air quickly
and ignite in time, even can not ignite, leading to difficulty in starting.
2.The good conditions of diesel engine
start-up
A.Must have enough start-up speed. If
starting speed is high, there will be less gas leakage in cylinder, time of
heat transfer from compressed air to cylinder wall will be shorter, will loss
less heat, so that gas temperature and pressure at the end of air compression
is higher. In generally, the speed is more than 100 r/min;
B.The cylinder needs better sealing.
This can further reduce the air leakage, ensure that the gas has enough
combustion temperature and pressure at the end of air compression, and the
compression pressure of the cylinder should not be less than 80% of the
standard value;
C.It is required that the fit clearance
between the engine and the engine parts be appropriate and lubricated well;
D.Batteries should have sufficient
starting capacitance and the starting circuit is in normal technical condition;
E.Starting oil quantity is in accordance
with the regulations, injection quality is good, and injection advance angle
should meet the requirements;
F. Use standard fuel oil.
3.When starting diesel engine for power
generation, crankshaft is failure to turn round.
When diesel engine starts up with a good
starting systems, if the transmission is in neutral position and press the
starter switch, the starter is noisy while the crankshaft cannot rotate, it
means a mechanical fault. The causes of engine crankshaft failure and the
diagnosis and repair methods are described below:
(1)The causes
A.Starter and flywheel teeth engage badly.
The impact between the ring gear and the starter gear will occur when starting
the engine, resulting in tooth damage or one-sided tooth wear. If the teeth are
damaged or worn seriously for more than three pieces, it is difficult for the
starter gear to mesh with the ring teeth.
B.When the temperature of the engine is
too high, the engine stops and extinguishes, and the heat is difficult to
dissipate. The piston ring and the cylinder adhere to each other at high
temperature, so the engine of diesel generator can not start after
cooling.
C.Because of the lubrication system
failure or oil shortage, the sliding bearings dry friction, so that ultimately
lock the crankshaft and can not start.
D.Injection pump plunger stuck.
(2)The methods of diagnosis and repair
A.If the flywheel has more than three
consecutive teeth damaged, and the starter teeth are exactly opposite, the two
gears will not mesh. In this state, the flywheel can start smoothly by prying
an angle with a crowbar and pressing the start button. For damaged flywheel
teeth, welding repair can be generally used;
B.When gear ring is loose, can check
installation port of flywheel shell starter. If gear ring is loose, need to
replace a new. When install, should heat the gear ring in heater box, and then
press on flywheel with heat gear ring, after cooling, can fasten on flywheel;
C.When gear ring teeth is damaged
seriously, can press gear ring, after overturn front end face of gear ring,
then can install on flywheel;
D.After check meshing of gears normal,
when starting can not turn. The reason is engine internal faults, such as
crankshaft locking, piston sticking cylinder, clutch sticking, etc., should
further observe. Can check whether the clutch is damaged or not, and then check
whether the plunger of the fuel injection pump is stuck and whether there is
foreign matter in the engine.
4.Diesel engine can turn round, but can
not start up
When starting the engine, the exhaust pipe
exhausts smokeless, and there is no explosion sound. Generally, diesel oil does
not enter the cylinder.
(1)The causes
A.There is not diesel oil in fuel tank;
B.There is some blockage in fuel filter
and oil-water separator ;
C.No oil supply in low pressure oil
pipeline;
D.Injection pump does not pump oil;
E.There is air in oil pipeline;
F.Valve timing misalignment. The opening
time of the valve is inconsistent with the piston's stroke in the cylinder. For
example, when the piston is compressed in the cylinder, the intake and exhaust
valves are open, and fresh air is driven out of the cylinder, so that there is
no combustion gas in the cylinder and it can not start;
G.The solenoid valve of the fuel injection
pump is damaged and in a closed state. Diesel oil can not enter the high pressure
chamber.
(2)How to solve?
A.Check whether the extinguishing line of
fuel injection pump is returned;
B.Check whether the fuel tank has oil,
whether the fuel tank switch is on or not;
C.Whether the fastening bolts of the
control rod and drive connecting disc of the fuel injection pump have fallen
off or not;
D.Unscrew the bleeding screw on the
injection pump and exhaust the oil with the hand pump;
E.Check whether the tubing is leaking or
blocked;
F.heck whether the fuel filter and
oil-water separator are blocked;
G.Diesel engine turns driven by the
starter, check whether the pump is pumping oil or not;
H.Remove and loosen the nozzle joint of
the injector, add the throttle to the end, press the starter switch, check
whether the fuel injection pump is pumping oil or not, if not, indicate that
the fuel regulating rod is stuck in the stop position ( rack hairpin); if type
A pump, the side cover of the fuel injection pump should be removed for inspection
and troubleshooting; if type P pump, appropriate measures should be taken to
deal with it;
I.Check whether the
valve timing is accurate, if not corrected, adjustments should be made.
In the previous:6. Fuel blocking murderer
The next article:4. Reasons and Solutions for Common Faults of Cummins Diesel Engine