Causes of High exhaust temperature at all unit-
Factors contributing to increase exhaust temperature are-
High Scavenge air temperature (Air cooler fouling, Ambient climate condition)
Fouling of air and gas passages
Fouling of T/C
Wrong camshaft position (faulting timing of fuel pump & exhaust valve) [incomplete combustion, after burning]
Wear of Fuel Cam and Exhaust Cam
Bad fuel quality
Inadequate FO purification
Overloading (such as hull fouling, propeller blade bending)
High exhaust temperature for one cylinder
Faulty fuel valve & fuel pump (poor atomization, late injection, after burning, or incorrect timing of this unit)
Leaky exhaust valve
Scavenge fire in this unit
Blow pass Wrong adjustment and damaged cam
Insufficient cooling water to this unit
Cause of decrease exhaust temperature on one unit
Air in fuel valve
Faulty fuel valve (ie. Needle valve lifts too low)
Defective suction valve in fuel pump
Fuel pump plunger sticking or leaking
Smoky Exhaust
Overload Defective fuel valve
Scavenge fire
After burning
Unstable fuel
Insufficient air supply
TC rpm not corresponding with engine rpm
Colour of Exhaust
Blue Excess cylinder oil, leak of oil cooled piston
White Excess water and air, one unit misfire
Black More fuel, fuel valve leak, ignition too late
Yellow High Sulphur content (Normal 1 – 1.5%)
Colourless Good
What point do you check when engine is smoky ?
To check
1) Fuel temp
2) Charge air temperature & pressure check (by light spring card)
3) Suction air filter is dirty or choke
4) Check fuel valve
What should be carried out ?
To be taken draw card & evaluated the combustion pressure.
Engine overload indication
Speed drop
High exhaust temperature at same rpm
More fuel consumption
Causes of engine overload
Hull fouling (caused by marine growth)
Propeller damaged
Shallow water
Heavy weather
Cause of excessive noise from crankcase
1) Slack chain (or) worn gear
2) Knocking from slack bearing
3) Slacken or break bolts, studs
4) Engine overload
5) Lubrication fault (insufficient oil pressure, poor quality, chock oil passage, failure of oil pipe)
6) Piston ring blow pass
Cause of M/E speed reduce on the way (Ship’s speed slowdown)
Cause Improper combustion of ME
1) Seized or leaky fuel pump plunger
2) Sticking fuel valve spindle
3) Burst fuel delivery pipe
4) Choked fuel line filter
5) Choked air inlet filter
6) Water in fuel oil
7) Overloading of engine
a. Fouling of propeller
b. Increased propeller slip due to heavy weather
8) In case of scavenge fire
Remedies
1) Take all Indicator cards
2) To consider the developed power
3) Evaluate combustion and expansion process, Pmax and Pcamp from out of phase diagram
4) Check cylinder tightness
5) Evaluate exhausting and scavenging process from light spring diagram
6) Defects found should be rectified as soon as possible
Why causes that engine start with air but no turn ?
1. Air pressure low
2. Faulty open of valve / stop valve/ bottle isolating valve to distributor
3. Turning engage (Turning gear inter lock)
4. L.O pump not starting.
Why causes that engine not ignite but engine turn ?
1. Governor tip (over speed trip)
2. Fuel system fault (Settling & service tank no Oil / F.O pump not start)
3. Air pressure low & so compression pressure low
4. Air in fuel pump, pipe line or Fuel valve
5. Incorrect air staring timing.
How would you investigate and find the cause of an engine cannot start ?
If air line is Ok or not,
1. Insufficient air pressure
2. Air staring valve sticking
3. System air lock
4. Defective distributor
5. Water in fuel
6. Fuel line air lock
7. Defective nozzle
8. Too late fuel timing (faulty fuel pump)
9. Poor compression
10. Lack of scavenge air
11. L.O low temperature
12. Safety interlock.
Action when engine cannot start
1. Inform to bridge
2. Check the air bottle
3. Check inter lock system (Turning gear, L.O, JKT FW, F.O pressure) and telegraph position.
4. If no rotation of flywheel when starting check starting air system (automatic air staring valve, air distributor, air staring valve, linkage of air staring mechanism)
5. If rotation of flywheel when starting, check fuel system.
6. Due to poor combustion, lack of scavenge air, too late fuel pump timing, fuel line air lack defective nozzle.
Special care during reduced speed
01) Increase cylinder oil.
02) If necessary change H.O to DO.
03) If necessary, run auxiliary blower.
04) Check temperature & pressure of L.O, F.W & scavenge air.
05) Check exhaust smoke & temperature.
Drop of Engine Speed
Causes for the trouble that the engine speed, in some cases, drops during operation in spite of the correct position.
01. Increase in the resistance of ship’s hull
02. Propeller damaged.
03. Sailing in shallow water
04. Change in the centerline of the shafting increased resistance.
05. Air / gas / steam remains in the fuel injection pump or in the fuel line. In the case, open the air vent valve, which is used for priming, and remove the air from the fuel oil lines
06. Fuel oil includes water; Wastewater should be removed form the service tank at regular intervals, or to be separated by means of the purifier.
07. Improper fuel quality.
08. Defective fuel valves(s) or fuel pump(s)
8a) Unsatisfactory functioning of the fuel injection valve.
8b) Insufficient pressure of the fuel injection pumps suction
8c) Abnormality of the fuel adjusting links device.
09. Oil pressure before fuel pumps too low.
9a) The fuel oil strainer is clogged or damaged.
9b) Insufficient supply of fuel oil due to unsatisfactory functioning of the fuel oil flow meter
10. The governor is sticking at the position of low engine speed.
11. Overheating of the moving parts .The engine should be stopped immediately
12. Unsatisfactory functioning of the exhaust valve and the dirty scavenge ports
13. A fire occurs in the scavenge chamber and air is insufficient. The engine must be stopped immediately
14. The turbocharger of the air cooler is dirty or damaged.
15. Slow down or shut down. Check pressure and temperature levels. If these are in order, check for faults in the slow down equipment.
Remedies
1) Take all Indicator cards
2) To consider the developed power
3) Evaluate combustion and expansion process, Pmax and Pcamp from out of phase diagram
4) Check cylinder tightness
5) Evaluate exhausting and scavenging process from light spring diagram
6) Defects found should be rectified as soon as possible
Sudden Stopping of Engine:
Causes for unexpected stop of the engine are as follows:
01. Drop of the system lubricating oil pressure and the turbocharger lub oil pressure actuates the emergency stop device.
02. The fuel oil supply to the fuel injection pump is shut of f by the causes of the stop of fuel circulating pump or fuel oil service tank is empty.
03. The fuel injection pump rack was pulled back suddenly to “0” position due to governor trouble.
04. When continuous fuel injection failed due to damage of the fuel oil line.
05. When the exhaust valve driving parts or the exhaust gas passages were damaged and gas discharge from the cylinder was troubled
06. Turbocharger is damaged.
Impossible of Reversing
If the camshaft does not move to the reversing position even the operation is made for Reversing causes for such impossible of reversing are considered as follows:
01. The start / stop lever is not in the stop position
02. The main engine speed is not under the speed enabling for reversing.
03. The valve on the starting air reservoir or air line is closed.
04. The valves on the control system control air line are sticked.
05. The pressure of the control system control air line is too low
06. The starting air pressure is too low
07. The stopper of the safety device for camshaft shifting gear is slicked.
08. Oil amount in the reversing oil bottles of the camshaft shifting gear is insufficient
09. The reversing pilot valve is not operational because of poor adjustment of the reverse handle.
Abnormal Explosion on Starting
Since cause for the abnormal firing on the engine staring are considered as follows, take care sufficiently at inspection before the starting, and at inspection and maintenance for the parts in question.
01. The manoeuvring handle position is too much increased and fuel is injected excessively.
02. Oil is remaining on the top of the piston head from the beginning.
03. Incorrect adjustment of the fuel injection n valve namely, insufficient opening pressure.
04. Insufficient facing up of the fuel injection valve nozzle and needle valve.
05. Incorrect setting of the fuel injection pumps rack and fuel injection timing.
06. Incorrect setting of the linkage between handle and governor
07. Incorrect setting of the governor
08. Due to sticking of the fuel injection pump delivery valve, the presence of foreign matters and incorrect facing up of the valve, fuel oil flows into the fuel injection valve too early and too long
In the following case, open the indicator valves of all cylinders and the engine should be operated by means of starting air only slightly longer and blow off the fuel.
a) In priming operation of the fuel oil injection line, the fuel oil entered on the piston head.
b) When the fuel injection valve is dismantled, fuel oil entered on the piston head.
c) Due to failure and repetition of starting operation, fuel oil injection in previous operation still remained on the piston head.
Knocking in Engine
The knocking and noise, during the engine operations caused by the engine trouble. The noise due to the knocking in the engine is, in many cases, produced by the loosened moving parts, early ignition and uneven load distribution among carried by the cylinders. It is very difficult to detect the noise by hearing.
If the noise is due to early ignition or due to uneven load distribution among the cylinders, fuel oil of the cylinder in question can be cut as an emergency measure. It can be early detected through the indicator diagram of the cylinder in question where the noise comes from ignition timing and uneven load distribution among the cylinder.
1. In case of early ignition, the following things are considered.
a) Leakage in the fuel injection valve or poor its spring pressure.
b) Incorrect adjusting of the fuel injection pump.
c) A large amount of low viscosity oil mixed in fuel oil.
2. In case of uneven load distribution among the cylinders, the following things are considered.
a) Incorrect adjustment of the fuel injection pump
b) Incorrect adjustment of the fuel adjusting links.
Diesel knock ~ Due to rapid burning of the charge of fuel oil accumulated during the delay period between the time of injection & ignition.
Cause of excessive noise from crankcase
1) Slack chain (or) worn gear
2) Knocking from slack bearing
3) Slacken or break bolts, studs
4) Engine overload
5) Lubrication fault (insufficient oil pressure, poor quality, chock oil passage, failure of oil pipe)
6) Piston ring blow pass
Rise in Exhaust Gas Temperature
The exhaust gas temperature rise has a great effect on the life on the exhaust valve and also on the wear of the piston ring and cylinder liner. The causes for exhaust gas temperature rise are considered as follow.
All cylinders
1. Increased in engine load.
1a) The fouling and deformation of the ship’s hull increases resistance to a fairly great extent, liable to increase engine load.
1b) Bending of propeller blades due to drifting woods and going ground subjects the engine to an increased load.
2. Fouling of scavenge air passage
2a) Fouling of airside due to oil mist on suction casing and diffuser of the turbocharger
2b) Clogging of cylinder liner scavenge port by combustion products.
3. Fouling of exhaust gas passage.
3a) Combustion products stick to the turbocharger nozzles and the surface of turbine blades, thus clogging the exhaust gas passage and reducing the turbocharger efficiency.
3b) Failure of nozzles and blades of turbocharger caused by foreign materials results the reduction in the turbine efficiency.
4. Leakage of scavenging air
5. Insufficient suction air
6. Increased scavenge air temperature owing to in adequate air cooler function.
7. Inadequate fuel oil cleaning, or altered combustion characteristics of fuel.
8. Wrong position of camshaft (maladjusted or defective chain drive)
9. Wear of Fuel Cam and Exhaust Cam
Single Cylinder
1. Defective fuel valves, or fuel nozzles.
a) Due to the enlarged nozzle hole of the fuel injection valve, which was used for a long period of time?
1. Blow by in combustion chamber (A fire occurs in the scavenging chamber and air is insufficient)
2. The scavenging valve in the scavenging air trunk is damaged or opening and closing function of scavenging valve is not good.
3. Leaking exhaust valve.
4. Wrongly adjusted, or slipped, fuel cam (Check the fuel pump lead) (B&W)
5. Abnormal exhaust gas temperature or pressure in cylinder.
a) Exhaust valve closing timing is deviated due to clogging of orifice off exhaust valve driving gear, usually accompanying with a slight water-hammering of exhaust valve driving oil and causes deviation of exhaust gas temperature and pressure in the cylinder. (UEC)
Blow by of Exhaust Valve
If the following phenomena are observed during operation, damage of exhaust valve shall be doubted. Quickly stop the engine, dismantle the susceptible exhaust valve, make inspection and repair it or replace parts with spare ones if necessary.
1) Rise in exhaust gas temperature
2) Abnormality of compression pressure
3) Noise
4) Abnormal Pressure of cooling water pump.
Blow-Past
A Blow- past is the term used when combustion gases at high temperature leak past the piston between the piston rings and cylinder liner.
A Blow-past causes rapid local overheating, removing the lub oil film and causing further damage to the surfaces and possible piston seizure.
1) In two stroke engines, burning gases will enter scavenge spaces causing fouling, overheating and even scavenge fires.
2) In four stroke engines, these gases will enter the crankcase with sever risk of a crankcase explosion
Causes of blow-past:
Excessive cylinder liner wears.
Lack of cylinder lubrication
Worn, broken, stuck or poorly maintained piston rings.
Worn piston ring groove landings allowing rings to cant and jam
Carbon jamming rings in grooves.
Remedy of blow-past
Gauge the cylinder liner and renew if necessary
Overhaul piston
Clean piston ring grooves and gauge them
Machine or fit new groove inserts as necessary
Renew piston rings with correct clearances
Maintain cylinder lubrication and avoid overload.
When all unit scavenge fire broken out.
Engine power balance.
Timing checking.
Took indicator diagram.
Surging in Turbocharger
In case surging occurs in the turbocharger while the engine is in service, generally the following causes may be considered as reasons for such surging:
1) Rapid change in load Sudden fluctuation in rough weather or at the time of crash astern running.
2) Insufficient supply of fuel Due to clogging of strainers and incorrect adjustment of the circulating pump pressure
3) Abnormally of fuel system Due to sticking of fuel injection pump, damaged high-pressure pipe or the failure of plunger barrel.
4) Narrowed scavenging air passage Due to pronounced fouling on the top surface of the air cooler.
5) Narrowed exhaust gas passage Increase in the resistance of the exhaust gas discharging passages
6) Engine operation at overload Due to fouling of ship’s hull or damage of propeller.
7) Failure of turbine blade, nozzle or diffuser Turbine blade, nozzles or diffuser is remarkably fouled or damaged unexpectedly when they are opened for repair.
8) Increased air resistance The turbocharger suction filter is extremely dirty, or there is a great air resistance due to a small piece of cloth and vinyl etc. adhering to the filter surface.
Power Balancing of Engine
For economy and efficient running of an engine equal power should be produced from each cylinder. This is then said to be power balanced and it may be necessary to make some minor adjustments to achieve this.
Power produced is related to the quantity of fuel injected and balancing is carried out by small adjustment to individual fuel pump controls.
Adjustments are limited to ensure units are not overloaded, exhaust temperatures are not excessive and that pump control still cut of f when brought to stop.
Fuel pump rack positions and exhaust & cooling outlet temperatures from each cylinder should be noted.
Equal exhaust temperatures on their do not necessarily show an accurate balance.
Power balance can be checked by measurement from indicator diagrams by calculating the area or mean height form each cylinder.
If an engines operates in an unbalanced conditions, some bearings and running gear may become overloaded; this may cause overheating and bearing failure.
Overloaded in cylinder may cause piston blow past, with the corresponding dangers of overheated / seized piston.
Unbalance will also set up vibrations which, if maintained for prolonged periods, will cause fatigue from the fluctuating stress induced. This may in turn lead to fatigue cracking of metal in bearings , fracture in bearings studs or bolts, cracks in crankshaft and bedplate, and slackening or failure of holding down bolts.
For proper power balance, engine running condition should be normal by observation of the relevant temperature & pressure, particularly exhaust and cooling outlet temperatures, lubricating oil and turbocharger pressures. The exhaust should be clear of smoke and there should be no unusual noise or vibration.