Cooling water pumps
driven by direct reversing diesel
engines are usually of the straight impeller vane type pump with a
concentric housing to ____________./provide cooling water flow when the engine
is running either ahead or astern
The expansion tank for a
diesel engine closed cooling system is designed to maintain a constant head on
the system and ___________./allow for an increase in water volume as the engine
warms up
Which of the following
statements describes the function of an expansion tank in a diesel engine
cooling system?/All of the above.
The device allowing for
the change in volume of the cooling water in a propulsion diesel engine closed
cooling system is the _____________./fresh water expansion tank
The highest pressure in
any closed diesel engine freshwater cooling system is at the
_____________./cooling water pump outlet
In any diesel engine
closed freshwater cooling system, the lowest pressure exists at the
_____________./expansion tank atmospheric vent
Maintaining the lowest
possible scavenging air temperature at all times is not recommended due to the
possibility of the ________________./formation of excessive quantities of
condensate
The outlet from an
expansion tank of a closed freshwater cooling system should be piped to the
____________./jacket water pump suction line
The expansion tank in a
diesel engine closed freshwater cooling
system is located at _____________./the highest point in the system
A three-way thermostatic
control valve regulates the diesel engine cooling water temperature by passing
a portion of the water _____________./around the cooler
In a diesel engine closed
freshwater cooling system, the amount of coolant flowing through the heat
exchanger is controlled by the
_____________./thermostatic bypass valve
Temperature control
valves installed in the jacket cooling water system of a diesel engine,
modulates the rate of water flow through the __________./heat exchanger
The jacket water
temperature in a diesel engine closed
freshwater cooling system is normally controlled by _____________./the operation of the
thermostatic valve
Why do most temperature
control valves in diesel engine closed
freshwater cooling systems vary the flow of jacket water through the cooler
instead of through the engine?/Changing the rate of flow in the jackets could
cause localized hot spots.
How much will the jacket
water temperature normallyincrease between the inlet and outlet of medium
orhigh-speed diesel engines?/10° to 20°F
Using a cooling water
temperature of 225°F (107.2°C), instead
of 180°F (82.2°C) in an auxiliary diesel engine, will ______________./reduce
the opportunity for the formation of sulfuric acid in the cylinder bore exhaust
passages
Operating a diesel engine
for prolonged periods, with a closed
freshwater cooling system, at temperatures lower than the normal design
temperature can cause _____________./the formation of sulfuric acid
As a general rule, the
recommended operating water jacket outlet temperature range for medium and high
speed marine diesels with closed cooling systems is ______________./180° to
199°F
A closed freshwater
cooling system is commonly used with marine diesel engines because the
_____________./jacket water temperature is more easily controlled
In a diesel engine closed
freshwater cooling system where the cooling water pressure drop through the
engine is 10 psig, and the pressure drop through the heat exchanger is 4 psig.
The cooling water pump must produce a discharge head of at least _________/15
psig
In a diesel engine closed
freshwater cooling system employing a
radiator, proper water temperature can be
obtained by _____________./adjusting the radiator louvers
Which of the listed
effects would the film of alkaline
chromate have on the metal surfaces of the cooling systemof a diesel
engine?/Protects metallic surfaces from corrosion
Ethylene glycol, when
used as a coolant in a closed cooling system for a diesel engine, is more
advantageous than untreated raw water
because it _____________./has a lower freezing point and higher boiling point
A diesel engine cooling
water system with a pH factor of 3.0 indicates a condition of
____________./excessive acidity
In a diesel engine
cooling water system, a pH of 6.0
indicates a/an ______________./slightly acidic condition
The pH value of water in
a diesel engine closed cooling water
system should be maintained between _____________./8.0 to 9.5
A two stroke diesel engine exhaust temperature will be
lower than a four stroke diesel engine of the same displacement because the
__________. I. mep is lower and the scavenging air is cooling the exhaust gases II. valve overlap in a four stroke
diesel e/I only is correct
The temperature at which
an adjustable bellows type thermostat
valve is set by ______./changing spring compression to oppose the bellows
High diesel engine
cooling water temperatures can be caused by _____________./all of the above
High diesel engine
cooling water temperatures can be caused by _____________./air in the cooling
system
Higher than normal jacket
water temperatures occurring in all cylinders of a diesel engine can result
from a/an __________./clogged sea
suction strainer
Which of the following
problems will cause above normal cooling
water temperatures in a diesel engine using a closed freshwater cooling
system?/Eroded baffle in the cooler
If the jacket water
temperature of an operating diesel
engine suddenly rises above normal, the cause can be attributed to _____________./a clogged raw
water sea suction
If the coolant
temperature of a closed cooling water system for a diesel engine gradually
increases, the trouble usually is _____________./an excessive accumulation of
scale in the heat exchanger
Some diesel engines are
fitted with a thermometer in the cooling water outlet from each cylinder. If
the cooling water temperature from all cylinders begins to rise above normal,
you should suspect _____________./overloading in all cylinders
You are operating a main
propulsion diesel engine at a constant
load when the jacket water temperature begins to rise. This could be caused by
____________./a piston about to seize
Immediately after
starting a diesel engine, normal raw waterand jacket water pressures are
indicated. However, thejacket water temperature continues to rise. If there is
nochange in the sea temperature, you should suspect _________./a jammed
three-way thermostatic valve
The main propulsion
diesel engine jacket water temperature rises above normal, with the raw water
sea suction and the expansion tank water level being normal. Which of the following problems is most likely the
cause?/Faulty thermostatic bypass valve.
Some diesel engines are
fitted with a thermometer in the cooling water outlet from each cylinder. If
the cooling water temperature from an individual cylinder begins to rise, you should suspect
_____________./overloading of that cylinder
One result of operating a
diesel engine at light load with excessively low cooling water temperatures is
a/an _______./increase in cylinder misfiring
If the jacket water
temperature in an auxiliary diesel
engine cooling system is lower than normal, the probable cause is
_________./faulty operation of the thermostat
Prolonged operation of a
diesel engine with a closed cooling water system, at lower than normal designed
operating temperatures can
_____________./cause sulfuric acid formation
A faulty thermostatic
bypass valve, in a diesel engine cooling
system, can result in _____________./excessive time required for warming-up
An emergency diesel
generator cooling system is equipped with an automotive type thermostat. If the
thermostat bellows loses its charge, the
thermostat will _____________./close, and the engine coolant temperature will
increase
Cooling water pumps
driven by direct-reversing diesel
engines are usually ____________./straight impeller vane with concentric
housing
If the operating element
of a thermostatic valve installed in a diesel engine cooling system
malfunctions, it may result in
______________./improper temperatures
Which of the following
conditions will develop if the flow of "raw" cooling water to a
diesel engine is obstructed?/The jacket water temperature will rise.
Diesel engine exhaust gas
temperatures can be used to determine
individual cylinder _____________./performance
All of the diesel engine
cylinder firing pressures are normal,
yet all of the exhaust temperatures are low. Which of the following situations
is responsible for this
condition?/Light load
Which of the following
factors tends to increase scale
formation on the saltwater side of a heat exchanger used in a diesel
engine cooling water system?/Operating the engine while maintaining a high sea
water outlet temperature.
Diesel engine exhaust
temperatures may be used to indicate _____________./all of the above
Cavitation erosion in the
cooling water system of a diesel engine usually occurs at the pump impeller,
and on the waterside of the
_____________./engine cylinder liners
High firing pressures and
a low exhaust temperature in a diesel engine may result from
_____________./early fuel injection timing
If the raw water supply
pressure for a diesel engine cooling system is below normal, you should check
for a ____________./clogged sea strainer
In a closed cooling water
system, which of the following problems can cause the water pressure to
fluctuate?/Air entrained in the cooling water.
High exhaust temperature
and black smoke exhausting from an auxiliary diesel engine can be caused by
_____________./engine overload
Which of the following
problems can cause fluctuating pressures
in the closed cooling system of a main propulsiondiesel engine?/Cavitation in
the cooling water pump.
Which of the following
statements is correct concerning diesel
engine cooling water systems?/At least two independent sea suctions are to be
provided for supplying water to the engine jackets or to the heat exchangers.
Maintaining the proper
fuel oil temperature will result in _____________./improved atomization
To successfully reduce an
excessively high diesel engine exhaust gas temperature, you should
_____________./reduce the load on the engine
Which of the following
statements is correct for the design and installation of diesel engine cooling
water systems?/Drain cocks are to be provided at the lowest points of all
cylinder water jackets.
Coolant can be lost from
a diesel engine jacket cooling water
system by leakage from _____________./all of the above
Failure to ensure proper
venting of the cooling system of a diesel engine can result in
____________./local overheating and/or internal corrosion
The knock occurring when
a cold diesel engine is started and continues while running at low speed, but
stops when the engine reaches normal operating speed and temperature, is
_________________./normal for these conditions
If a diesel engine's
exhaust temperature is abnormally high, the cause could be
____________./overloading of the engine
If the water level
dropped rapidly in the expansion tank of a closed diesel engine cooling water
system, you should suspect a
_____________./leak in the primary cooling system
Which of the following
conditions can cause oil to accumulate
in the cooling system of a diesel engine?/Defective oil cooler core.
A diesel engine is
operating with excessively high exhaust temperatures at all cylinders. To
correct this condition, you should FIRST _____________./reduce the engine load
One remedy for a high
firing pressure, in addition to a high exhaust temperature in one cylinder of a
diesel engine, is to ____________./adjust the fuel rack
If a diesel engine is
difficult to start and operates with the engine temperatures lower than normal,
you should suspect that the
_____________./compression pressures are below normal
How are the pressure and
temperature affected in a diesel engine cylinder during compression?/Pressure
and temperature increase
A diesel engine is
operating under a normal load with low firing pressures and high exhaust
temperatures. The most probable cause of this condition is ________________./a
restricted exhaust manifold
If the jacket water
temperature rises rapidly above normal in a diesel engine, you should FIRST
__________./reduce engine load
A 16 cylinder main
propulsion diesel engine is operating at 90% of full load. All cylinder exhaust
temperatures are indicated at 950°F, except the No. 7 cylinder which is indicated at 1100°F. All fuel racks are at
21-22 mm except No. 7 which is at 16mm. /Replace and retime No. 7 cylinder fuel
pump.
In a diesel engine
cooling system, the high temperaturealarm contact maker will be activated on
excessively highwater discharge temperature from the ____________./engine
jacket water outlet
Cooling water pumps
driven by direct reversing diesel
engines are usually of the straight impeller vane type pump with a
concentric housing to ____________./facilltiate bi-directional operation
In a diesel engine jacket
water cooler, with seawater cooling the
fresh water, the ___________./jacket water pressure should always be greater
than the sea water pressure
If an auxiliary diesel
engine coolant temperature is higherthan normal, but the thermostat is
determined not to be defective, you would suspect a/an ___________./dirty
jacket water cooler
When one cylinder has a
lower compression pressure and higher
exhaust gas temperature than any of the other enginecylinders, which of the
conditions listed will beindicated?/Leaky exhaust valve
If the firing pressures
in a diesel engine are high, although
the exhaust temperatures are normal, the cause may be _____________./worn
orifices in the injection nozzles
Cooling water pumps
driven by direct reversing diesel
engines are usually of the straight impeller vane type pump with a
concentric housing to ____________./to turn in either direction
The device most commonly
used to measure exhaust gas temperature of cyclinders is a
_____________./pyrometer
By comparing the exhaust
gas temperature of each cylinder, the operator can determine if the load is
balanced throughout the engine. The device most commonly used is a
_____________./pyrometer
High cylinder firing
pressure, accompanied by low exhaust temperature, can result from
_____________./excessively early injection timing
Which of the conditions
listed would cause simultaneous high cylinder firing pressure and low exhaust
temperature?/Excessively early injection timing.
When high firing
pressures and low exhaust temperatures
occur simultaneously in a diesel engine, this may be a result of ____________./early timing of fuel
injection
Operating a diesel engine
under light loads and at low
temperatures for an extended period can result in _________./formation
of carbon on the intake and exhaust ports
When starting a diesel
engine at temperatures below 70°F, the frictional resistance to turning will be
_____________./proportional to the lube oil viscosity
Which of the following
relationships should occur between the temperature developed in a combustion
space, and the compression ratio of the engine?/Higher compression ratios
create higher temperature.
The diesel engine starter
least likely to be affected by low ambient temperatures, is the
_____________./hydraulic starting system
A pyrometer is an
instrument used to measure the temperature of the diesel engine
_____________./exhaust
Thermocouple pyrometers
are used on large, main propulsion diesel engines to indicate the temperature
of the ________./exhaust gases at various locations
When the cold valve lash
is less than that specified by the manufacturer, diesel engine valves,
operating at normal temperatures, will
______________./close later than normal
Low cylinder compression
pressure and a high exhaust temperature
may indicate ______________./leaking valves
In a diesel engine
exhaust system, the cooling of the exhaust gases below their dew point, will
result in ____________./sulfuric acid corrosion
One of the purposes for
water cooling the exhaust manifold in marine diesel engine is to
__________./reduce excessive heating of engine room
If the jacket water
temperature rises rapidly above normal in a diesel engine, you should FIRST
__________./reduce engine load
In comparing engines of
equal horsepower, higher exhaust gas temperatures occur in a/an
_____________./four-stroke/cycle engine
You are operating a
16-cylinder diesel engine at 75% load, turning 900 RPM. All exhaust
temperatures are between 900°F and 950°F, except the #3 cylinder, with an
indicated reading of 750°F. All fuel rack settings are between 21 and 22
millimeters, with th/Increase the #3 rack setting and watch the exhaust temperature. |
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