fuel, timing and engine performance

Question 1

2 ancillary equipment that can be driven by timing chain

Answer 1

lo pumps
cooling water pump
camshaft

Question 2

speed of cam shaft on 4 stroke and 2 stroke

Answer 2

4 stroke is 2:1

2 stroke is 1:1

Question 3

importance of maintaining fuel at correct viscosity for injection

Answer 3

Good atomisation

less fuel used

Question 4

importance of testing lube oil regularly

Answer 4

check for water, water can cause corrosion. check for fuel, hfo can cause sludge, mgo can thin the oil and cause a crank case explosion, check the condition of the oil. and you will be able to check the condition of the engine Incase of any metal fragments.

Question 5

importance of ensuring the rotation of the exhaust valves

Answer 5

creates a more uniform wear to the valve rather than concentrated wear.

prevents sticking

reduces high thermal stress on the valve

Question 6

actions for the turbo charger repeatedly surging

Answer 6

causes, no fans on, dirty filter, dirty compressor, dirty turbine, EGB blockage.

if it happens you should slow down the engine, this will slow the turbine, then the requirement for air will be lower, start blowers, investigate and do cleaning

Question 7

air start manifold pipe overheating in one unit

Answer 7

this means that the air start valce is open, stop the engine or on a 2 stroke you can also lift the cam follower off of the cam. this is to prevent an air manifold explosion

Question 8

actions in a low scavenge air temperature alarm

Answer 8

you would change the charge air cooler temp by the valve to stop the air being as cool

Question 9

actions for engine miss fires, fuel rail pressure low alarm activates, booster pump pressure is high

Answer 9

this would mean that the filter is high so swap over the filter, and clean the blocked filter

Question 10

actions for turbo charger repeatedly surging in heavy weather

Answer 10

slow down the engine to reduce the effects of the turbo charger speeding up and slowing down

Question 11

actions for a turbo charger excessively vibrating at full sea speed

Answer 11

reduce the load, if this works then the it indicates the turbo charger is dirty, so do a turbo wash. if no it indicates damage to the turbo charger.

Question 12

actions when there is overheating of an air start branch pipe to one cylinder during manouvering

Answer 12

air start valve open

ask bridge to stop and change over engine

Question 13

actions for high main bearing temperature

Answer 13

slow Down the engine to prevent a crankcase explosion, reduce the load, monitor the temperatures.

Question 14

how to calculate PLANN

Answer 14

mean effective pressure p=a/l
use plannimeter to find area a=lxp
length of stroke divided by piston bore 
speed in revs per second 
if a 4 stroke divide by 2

Question 15

effect of early injection

Answer 15

higher to tdc to higher pmax
overloads the unit Imbalance in the unit
possible vibrations

Question 16

effect of late injection

Answer 16

injection further away from tdc lower pmax
incomplete combustion
high exhaust temps

Question 17

on a 4 stroke why are tappet clearances essential

Answer 17

they allow for thermal expansion and they control the correct timing of valves and allow the correct combustion

Question 18

if a tappet clearance is too large

Answer 18

causes late opening, not enough air in and out.
a late opening and early close close can effect combustion
creates shock loads throughout valve spindle

Question 19

if a tappet clearance is too small

Answer 19

when the valve heats up it will expand and the valve will be held off of the seat.
gases can eat away at the valve.
open early and late close

Question 20

procedure to start a small diesel engine using a staring handle

Answer 20

check fuel
oil level
coolant
all valves are open
engage the handle
open the decompression level
using lever get up to Speed
close decompression lever
engine will start

Question 21

eight reasons for difficulty starting a small engine with the lever

Answer 21

not turning the lever fast enough
cold starting conditions
no fuel
fuel pump not working
jacket water not working
flooded with fuel
dirty fuel filter
air filter blocked

Question 22

tests carried out on a fuel injector after a overhaul

Answer 22

put in test rig
pump up to the breaking pressure
check if it operates, check for dribbling,
check for good atomisation, check there’s no dribbling after the operation