What Operational Difficulties might Occur While Engine Is Running

Find out the reasons of various problems
that may occur while engine is running like increase in exhaust temperature etc
and how to troubleshoot the same with ease. Here we have discussed some of the common
problem that arise when engine is running and if we follow the remedies given
below, we can solve our problem. Let’s have a look at them one by one.

Exhaust
temperature of all cylinders increase

1)      Cause : Increased air temperature due to
fouled air cooler.
Remedy : Keep fuel control such that
exhaust temperatures are within permissible limits. Clean air cooler at first
available opportunity. 
2)     Cause : Fouling of air and gas passages
of turbocharger.
Remedy : Carry out air side water washing
of turbocharger. To carry out turbine side water washing reduce engine as
recommended by makers.
3)     Cause : Change in combustion
characteristics of fuel in use.
Remedy : Keep temperatures within limit
and inform office so that matter can be taken up with bunker supplier.

Exhaust
temperature of individual cylinder increases

1)      Cause : Fuel valve is defective.
Remedy : Replace fuel valve with spare
overhauled one. Dismantle removed injector and overhaul it.
Main Engine Exhaust Temperature High and Low Reasons

2)     Cause : Exhaust valve is leaking.
Remedy : Replace defective exhaust valve
and overhaul it.
3)     Cause : 
Blow- by causing leaky combustion chamber. (This may be indicated by
hissing sound heard when scavenge drain valve is opened. Depending on condition
of rings smoke or sparks may also issue from drain.
Remedy : Inspect rings from scavenge
ports and replace if faulty, at first suitable opportunity.

Exhaust
temperature of all cylinders decreases

1)       Cause
: Decrease in scavenge air temperature. 
Remedy : Check temperature control valve
of scavenge air and raise scavenge air temperature.

Exhaust
temperature of individual cylinder decreases

1)       Cause : Air or vapour lock in fuel pump and
fuel valve 
Remedy : Purge air/vapour from fuel pump
and/or fuel valve.
If this does not help injector may have
to be replaced, with spare overhauled one. If it has sticking valve spindle or
broken spring of needle valve then it can result in air lock in fuel injector.
Dismantle removed injector and overhaul it.
2)     Cause : Suction valve of valve controlled
fuel pump is
defective.
Remedy : Overhaul suction valve of fuel
pump.
3)     Cause : Plunger of jerk type fuel pump is
sticking or leaking.
Remedy : Replace fuel pump with spare
overhauled one.        Note : Sticking of
fuel pump plunger can take place while changing over to heavy oil from diesel
oil, if heating is not gradual and uniform. A worn out helical edge of plunger
can result in late injection and consequent increase in exhaust temperature.

Engine
RPM decreases

1)      Cause : Fuel pressure before fuel pump is
too low.
Remedy : Raise fuel pump pressure to its
normal value.
2)     Cause : Significant presence of water in
fuel.
Remedy : Drain water from fuel. Check for
source of ingress of water and rectify it.
3)     Cause : Engine slow down device is
actuated.
Remedy : Check pressures and temperatures
which actuate slow down device and restore to normal value if there is any
deviation beyond acceptable range. If these values do not show any abnormality
then check for faults in slow down device.

4)     Scavenge fire Cause and Remedy

Remedy : If fire is small then reduce
engine speed to ‘Dead Slow’, increase cylinder lubrication and keep away from
relief valves of scavenge manifold and crankcase. Fire may die down on its own.
Increase engine speed gradually with constant watch on it. If fire does not
re-ignite then clean scavenge spaces at first opportunity and inspect condition
of piston rings, stuffing box, piston rod. If fire is severe then reduce speed
to ‘Dead Slow’ and stop engine in consultation with bridge. Isolate blowers and
close valve in supply duct. Keep away from relief valves of scavenge manifold
and crankcase.
        
 
Do not open scavenge manifold or
crankcase till temperature falls below 100 degree Celsius. Then clean scavenge
space. Inspect piston rod for straightness and alignment. This can be checked
by observing movement of piston and piston rod while turning engine on turning
gear by operating cylinder lubricators manually. Inspect liner surface. Inspect
stuffing box, bottom of scavenge box and diaphragm for cracks. If affected
piston cannot be overhauled immediately then engine will have to be operated by
reducing power of affected cylinder or by cutting it off from operation. 

Smoky
exhaust during acceleration

1)      Cause : Turbine RPM lagging behind engine
RPM.
Remedy : Reasonable smoke during
acceleration is normal. If engine is running at ‘Dead Slow’ for quite some time
then turbocharger RPM may become so slow that it may not pick up after
increasing fuel. During such time engine may smoke. Engine may have to be
stopped and restarted with higher fuel notch to rectify it. If smoke is heavy
governor loading programme will have to be checked.
2)      Cause : Air supply to low due to fouling of
air and exhaust passages.
Remedy : Clean fouled spaces at first
available opportunity.
3)     Cause : Defective fuel injector or
trumpets on nozzle tip due to defective nozzle cooling.
Remedy : Replace defective fuel injector
with spare overhauled one.

So these were some of the problems that
you might face. If you faced any problem and want to share with us, please feel
free to comment below.

You Might Like to Read These Posts Too:

Leave a Reply

Your email address will not be published. Required fields are marked *

Special Topics For You

Read these

What Operational Difficulties are there while Star... 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 g...
Main Engine Exhaust Valve Parts, Working and Overh... Marine Diesel Engine nowadays employs the hydraulic mechanism of opening and closing the exhaust valve. Just like other machineries, it also require...
What is Overspeed Trip, its types and how it works An overspeed trip is required to ensure that fuel supply will be cut off from engine if its speed exceeds the predetermined value. Over speeding wi...
Every Day checks in Engine Room Rounds from Funnel... When a duty engineer is taking rounds, half of the problems or troubleshooting can be done by them, if they check the items below given properly. Th...
Oil Mist Detector Alarm: Actions to be taken and w... Oil Mist Detector is equipment which monitors the environment inside a crankcase space of an internal combustion engine and thus tells the engineer,...
Marine Engineering Practice Questions And Answer-P... Here are some of the questions for oral preparation for your engineer COC examinations. This article covers the Marine Engineering Practice question...
Engine Room Watchkeeping Rounds Guide for Marine E... In this article we will see about the things that you need to look after when taking the engine rounds. With the advent of UMS ship, the traditional...
Marine Engineering Practice Questions and Answers-... This is our second article in the Marine Engineering Practice Series which deals in questions related to the troubleshooting of the ship machinery e...
error: Content is protected !!