Cooling system — Engineering, Mashit 30

18 questions on cooling system, from the Engineering exam of Mashit 30. Fresh water and raw water, thermostat, heat exchanger and temperature. Every question is shown with its correct answer, as in the official question pool.

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Questions on Cooling system

1. In a closed cooling system, what is the function of the engine's fresh-water (treated water) pump? To use the water to carry the engine's heat to the raw water, through the heat exchanger.
2. What is the function of the raw-water pump in a closed cooling system? To supply water to cool the fresh-water system.
3. What characterises a combined (closed) cooling system? The engine is cooled by treated water, which is in turn cooled by raw (sea) water.
4. Which type of cooling system has cooling fins and a radiator? An air-cooled system.
5. The temperature gauge of a diesel engine reads 213°F. What should you do? The engine is boiling: stop it and find the cause.
6. The engine's coolant temperature gauge reads 180°C. What does this mean? The gauge is probably faulty.
7. What is the purpose of the pencil zincs (zinc rods) in the raw-water cooling system? To prevent galvanic corrosion of the parts of the raw-water system.
8. What is the purpose of the valve in the cap of the header (expansion) tank? To keep the water in the system at high pressure and raise its boiling point.
9. What does the temperature gauge on a diesel engine normally measure? The temperature of the water leaving the cylinder head.
10. What should you do when the engine overheats? Reduce the load and find the fault.
11. In a closed cooling system, what can cause a large and rapid loss of coolant? The engine overheating and boiling.
12. What is the purpose of the thermostat in the engine's cooling system? To let the engine run at a steady, constant temperature.
13. The thermostat in the cooling system has stuck open. What could the effects be? Over time it will cause damage, because the engine will run below its recommended temperature.
14. How often is it recommended to check the coolant level? Before each time the engine is run.
15. A heat exchanger (cooler) is typical of which type of cooling system? A closed cooling system.
16. Where is the thermostat usually fitted in the engine's cooling system? At the coolant outlet from the cylinder head.
17. What is the main job of the coolant pump in the fresh-water system? None of the above.
18. You have started the engine and find that no water is coming out of the exhaust. What could be the cause? The seacock (raw-water inlet valve) is closed.

More Engineering topics

• Engine principles — 17 questions
• Engine parts — 16 questions
• Fuel system — 27 questions
• Lubrication and oil — 21 questions
• Pumps — 11 questions
• Electrical system — 23 questions
• Propulsion and propeller — 15 questions
• Operating routine — 9 questions
• Fault-finding — 11 questions
• Safety and fire — 3 questions
• Calculations and units — 7 questions

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