What Operational Difficulties are there while Starting Engine

There are various types of difficulties that
you might face as an engineer while starting an engine. Here we have given some
of them.Below we have given some of the problems
that you might face at sea or even at land also with the engines. Let’s have a
look at the one by one.

Engine
does not start on air, with regulating handle in start position        

1)     
Cause
: Air Bottle pressure too low
Remedy : Check operation of air
compressors and start them to fill up air bottle.
2)    
 Cause : Air starting valves shut
Remedy : Check air starting valve on air
bottle and main air starting valve. Open them if not in working position.
3)    
 Cause : Main air starting valve does not
operate
Remedy : Bring main air starting valve in
working position using manual lever or tools provided if stuck. If valve is not
stuck check for pilot air line supply. This may involve checking electric
supply to concerned solenoid valve.
4)    
Cause
: Control air pressure low
Remedy : Check discharge pressure of
pressure reducing valve. If  low change
over to stand by pressure regulating valve. Investigate cause of low working
pressure of previous valve in operation. It can be clogged air filter, ruptured
diaphragm. Rectify it.

5)    
Cause
: Starting air interlock activated

Remedy : Check for the cause of interlock
activation. Check if turning gear is engaged, and disengage it if so. Check if
running direction interlock is activated. Confirm that engine turning direction
and camshaft position are identical.
Marine Engines

6)    
Cause
: Air supply to or from air distributor blocked
Remedy : If there is any valve in air
supply line then confirm it is open. If open and no air is coming to the
respective cylinder air starting valve then check for sticky air distributor
valve. If time is short try starting engine in another rotational position by
engaging turning gear and rotating engine to another rotational position so
that another distributor valve for another cylinder air starting valve comes
into operation.

Engine
turns too slowly or irregularly on starting air

1)      Cause : Some pistons of air distributor
are sticking.
Remedy : Overhaul starting air
distributor to free the sticky pistons.
2)      Cause : Some cylinder air valves are not
operating.
Remedy : Test valves for their operation
and overhaul defective ones.

Engine
turns on starting air but does not pick up on fuel

1)     
Cause
: Sluggish movement of fuel control shaft and associated linkages
Remedy : Lubricate and free the fuel
control shaft and associated linkages.
2)    
 Cause : Piston in stop piston is jammed. 
Remedy : If piston is jammed free
it. 
3)    
 Cause : Stop piston is activated
Remedy : Check pressures &
temperatures activating stop piston such as low lube oil pressure, high cooling
water temperature. Restore these parameters to normalcy if abnormal. If this is
normal then check for malfunction of pneumatic valve supplying air to stop
piston.
4)    
Cause
: Control air pressure to governor is low  
Remedy : Check air pressure and change
over air reducing valve if it is faulty.
5)    
Cause
: Air lock in the fuel injection lines, pumps & valves.
Remedy : Purge out air from fuel system
thoroughly.
6)    
Cause
: Pressure before fuel injection pump is low
Remedy : Check fuel booster pump
discharge pressure and bring it to normal.
7)    
Cause
: Fuel injection pump is faulty. In case of Bosch pump plungers may be
sticking. In case of valve controlled fuel pumps suction valves may be
defective.
Remedy : Identify the fault and rectify
it.
8)    
Cause
: Failure of governor amplifier.
Remedy : Rectify governor amplifier.
9)    
Cause
: Fuel pumps are worn out.
Remedy : Replace fuel pumps.

Fuel
is injected but does not ignite

1)      Cause : Presence of water in fuel
Remedy : Drain off water from fuel tanks,
prime fuel valves and fuel pumps. Check for source of ingress of water and
rectify.  
2)     Cause : Fuel valves defective
Remedy : Change fuel valves. Check and
overhaul removed fuel injectors.
3)     Cause : Compression too low (below 22
kg/cm2)
Remedy : Inspect piston rings through
ports in liner. Check for leaky exhaust valves.

4)     Cause : Fuel injection too late

Remedy : Check fuel pump timing and
adjust if required.
5)     Cause : Viscosity of fuel too high
Remedy : Raise fuel oil temperature to
attain required viscosity.

Initial
ignition is violent and safety valves lift

1)      Cause : Accumulation of oil on piston
crown
Remedy : Blow through cylinder with
indicator valves open to locate leaky fuel valve. Remove defective fuel valve
and replace with spare overhauled one.

Initial
ignition is violent and cylinder safety valves lift

1)      Cause : Accumulation of oil on piston
crown
Remedy : Blow through cylinder with
indicator valves open to locate leaky fuel valve. Remove defective fuel valve
and replace with spare overhauled one.
2)     Cause : Sluggish movement of fuel control
shaft or individual fuel pump rack making fuel pump injection high (for
respective fuel lever position.)
Remedy : Lubricate bearings of fuel control
shaft and free its movement. Lubricate individual fuel pump rack and make their
movement free.

3)     Cause : Scavenging air pressure is low

Remedy : Check auxiliary blower is
running. Check air and gas passages and clean if required.
(Note – If fuel oil is present on piston
crown due to first injection not igniting then due to scavenge air pressure low
this fuel does not get expelled and accumulates on crown causing violent
ignition before TDC)

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