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ABYC Diesel Certification 2024: Questions and Answers, Exams of Marine Engineering

A comprehensive set of questions and answers related to abyc diesel certification for 2024. It covers various aspects of diesel engine operation, maintenance, and troubleshooting, including fuel systems, cooling systems, exhaust systems, and electrical systems. Valuable for individuals preparing for the abyc diesel certification exam or those seeking to enhance their knowledge of diesel engines.

Typology: Exams

2024/2025

Available from 02/27/2025

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ABYC Diesel Certification 2024 | 100% Correct
Answers | Verified | Latest 2024 Version
minimum spacing between hull vent openings and fuel fill or vent fittings should be - ✔✔15 inches
thermal efficiency of a diesel engine is such that typical heat converted to useful power is approximately
what percent of total heat - ✔✔36%
What is the primary difference between the gasoline-fueled and Jen four stroke cycle and the diesel four-
stroke cycle - The intake stroke only brings air into the cylinder
Temperature controlled engine room exhaust blowers in a diesel powered boat are primarily used to -
✔✔Lower engine room temperatures
With some diesel engines it is necessary to use what when cold starting - ✔✔Heat
When setting up a piping system for exhaust gases the number of sharp bins should be kept to a
minimum to - ✔✔Prevent excessive exhaust back-pressure
Who does not have requirements that apply to exhaust components and hose types - ✔✔U.s. coast
guard
What is the most likely exhaust related cause for excessive engine operating temperature - ✔✔Exhaust
elbows that are old and clogged
an engine equipped with an exhaust mixing elbow is installed below the waterline what device must be
installed in the raw water discharge hose ahead of the mixing elbow - ✔✔Siphon break
Upon inspection of the wet exhaust system the technician notices that the exhaust hose is burned near
the elbow tech a says that replacing the hose will correct the problem. Tech b says that the problem is
most likely with the cooling system which tech is correct? - ✔✔Tech b
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ABYC Diesel Certification 202 4 | 100% Correct

Answers | Verified | Latest 2024 Version

minimum spacing between hull vent openings and fuel fill or vent fittings should be - ✔✔15 inches thermal efficiency of a diesel engine is such that typical heat converted to useful power is approximately what percent of total heat - ✔✔36% What is the primary difference between the gasoline-fueled and Jen four stroke cycle and the diesel four- stroke cycle - ✔✔The intake stroke only brings air into the cylinder Temperature controlled engine room exhaust blowers in a diesel powered boat are primarily used to - ✔✔Lower engine room temperatures With some diesel engines it is necessary to use what when cold starting - ✔✔Heat When setting up a piping system for exhaust gases the number of sharp bins should be kept to a minimum to - ✔✔Prevent excessive exhaust back-pressure Who does not have requirements that apply to exhaust components and hose types - ✔✔U.s. coast guard What is the most likely exhaust related cause for excessive engine operating temperature - ✔✔Exhaust elbows that are old and clogged an engine equipped with an exhaust mixing elbow is installed below the waterline what device must be installed in the raw water discharge hose ahead of the mixing elbow - ✔✔Siphon break Upon inspection of the wet exhaust system the technician notices that the exhaust hose is burned near the elbow tech a says that replacing the hose will correct the problem. Tech b says that the problem is most likely with the cooling system which tech is correct? - ✔✔Tech b

If you do not refill the raw water system with a winterizing solution for long-term storage after draining the sea water the system is prone to - ✔✔Oxidization Replacement of a failed sea water pump impeller should normally include - ✔✔Checking all downstream components for impeller pieces During a sea trial for a complaint of high-speed overheating the technician finds that the cooling hoses are swollen and very firm when squeezed and the exhaust hose very hot to the touch this most likely indicates - ✔✔Exhaust manifold or risers are blocked Technician a says that you must observe USCG regulations when choosing and installing c Cox. Tech b says there is no standard for Seahawks or their installation. What tech is correct - ✔✔Neither tech is correct during engine operation a technician notices that the water level is low in the sea water strainer this might indicate which of the following - ✔✔sea water strainer has an air leak and sea water inlet problems The most common cause of low coolant temperature in a closed cooling system is - ✔✔A faulty thermostat Auxiliary heating devices such as cabin heaters and water heaters may require - ✔✔Using a restrictor fitting and installing the device lower than the expansion tank The transfer of heat through the fluid in the cooling system is known as - ✔✔Convection Exhaust gas is leaking into the coolant system may be caused by a defective - ✔✔Cylinder head gasket Coolant conditioner filters should be replaced - ✔✔Follow the manufacturer's recommendation Exhaust gas is leaking into the coolant system may be caused by a - ✔✔Cylinder head gasket

To assure adequate fuel supply the technician must measure fuel inlet restriction using - ✔✔Vacuum gauge Compared to gasoline diesel fuel is more susceptible to - ✔✔Microbial contamination and Diesel sludge contamination The most frequent cause of diesel engine problems is due to - ✔✔Fuel contamination According to abyc standards diesel fuel system distribution and return lines must - ✔✔Be u s coast guard type A High pressure fuel lines that have been removed - ✔✔Should be capped to keep dirt out A customer complains the engine idle is rough. Tech a says air in the fuel system may be the cause. Tech b says the fuel shut off solenoid is not operating. Who is right - ✔✔Tech a All times injection pumps are time to - ✔✔As per engine service manual What would happen if a high pressure fuel line was replaced with a line longer than the original line - ✔✔The timing would change because of the extension of the fuel line Which of these should be done first to find the cause of a misfire on a diesel engine - ✔✔Find the misfiring cylinder At what temperature to diesel engines ignite atomized diesel fuel - ✔✔750 degrees Fahrenheit or 400 degrees c and above What are the four stroke cycles For diesel - ✔✔1 intake 2 compression

3 power (injection) 4 exhaust stroke Roots-type blowers spin at approximately how many times the engine RPMs - ✔✔3 x What are the most common turbocharger failures - ✔✔Poor lubrication or oil seal failure At what pressure does gasoline engines versus diesel engines compress - ✔✔Gas 180 PSI vs diesel 380psi What is a manometer used for - ✔✔Back pressure check on exhaust What is needed for engine installations that are below a boat's waterline - ✔✔Water lift muffler systems What causes rubber exhaust hoses to overheat severely - ✔✔Water pump failure while engine is running What is a pyrometer - ✔✔A thermometer Exhaust manifold risers that have hotspots or manifest itself as over pressurized and swollen engine hoses could be caused by - ✔✔Rust blocking the flow of cooling water Exhaust manifold risers need to be replaced how often for saltwater - ✔✔3 to 5 years And heat exchangers what direction do coolant vs. Water flow - ✔✔Opposite of each other If there is milky color on a dipstick this could indicate - ✔✔Water mixing with oil created buy a leak in one of the exchanger tubes For adjustment titaness of belts for every 12 inch of belts pan there is about how much flex - ✔✔Half an inch of belt flex

the owner is complaining of low top end speed. On a sea trial under a full load you measure exhaust gas temperature and boost pressure. You explain to the owner you feel the engine is overloaded based on - ✔✔The boost is lower than specification and the temperature is above specification The operator of a diesel boat has a complaint of low power and no smoke the technician should first check the - ✔✔Fuel pressure Add high-speed the raw water pressure shows heavy fluctuation as indicated on a pressure gauge. A possible cause would be - ✔✔Debris in the sea water pick up A ruptured oil cooler core may result in - ✔✔Water in the oil system or oil in the water system Which factors must be considered when installing adjusting transmission shift - ✔✔Centering and fold travel, idle speed and full throttle Diesel engines are what percent more efficient in fuel economy compared to gasoline - ✔✔10 to 15% The typical voltage drop on voltage sensing battery combiners is - ✔✔0. What is the ideal amounts of drops per minute for a stuffing box - ✔✔1 to 3 protective guards are required on exhaust systems whenever persons or gear might come in contact with the exhaust system where the temperature exceeds - ✔✔200 degrees Fahrenheit The middle on the inside diameter of a diesel fuel filter system shall be - ✔✔1 and 1/ What tool can be used to identify misfiring diesel engine cylinder - ✔✔Infrared heat gun

ABYC states that a failure occurs with the shaft seal while operating at low speeds no more than how many gallons per minute can enter - ✔✔2 gallons What are the most common organisms that can live in diesel tanks - ✔✔Bacteria, mold fungus In respect to a water lift systems, is necessary to have a what? In the event the engine will not crank to prevent water back into the cylinders - ✔✔Drain A turbocharger oil seal failure can cause - ✔✔Engine to run away The owner complains that the throttle handle will not hold position. What adjustment Mike correct this problem? - ✔✔Throttle friction adjustment at the control head Gel cell batteries shall not be charged at more than how many volts - ✔✔14.1 volts Electrolyte loss and batteries is most often caused by - ✔✔System overcharging A fully charged battery at rest will show a minimum of how many volts - ✔✔12.6 volts Battery switches are required for any battery when - ✔✔Over 800cca When using a hydrometer any cell less than how many points is considered a bad cell - ✔✔0.50 points When using a conductance tester what percentage of the battery CCA do you use - ✔✔50% How many vac is acceptable leakage for a alternator rectifier - ✔✔0.4 v AC Typical alternator RPM is usually somewhere between how many times the engines RPM - ✔✔1.5 to 2 times