Fault-finding — Engineering, Mashit 30

11 questions on fault-finding, from the Engineering exam of Mashit 30. An engine that will not start, stops, misfires or overheats. Every question is shown with its correct answer, as in the official question pool.

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Questions on Fault-finding

1. What will make a diesel engine run irregularly? Air getting into the fuel.
2. When you try to start a diesel engine, it turns over well but does not start. What could be the cause? No fuel is reaching the injectors.
3. You started a diesel engine and after a few minutes it stopped by itself. What could be the cause? Lack of fuel or a fault in the fuel system.
4. Why is it undesirable to run the engine at low speed for long periods? Soot may build up on the piston, the valves and the injector tip.
5. By which signs can you tell that the engine is overloaded? Coolant temperature too high and black smoke from the exhaust.
6. While the engine is running it starts to "stutter". What could be the cause? The fuel tank has probably run dry and the lift pump is drawing in air as well.
7. While underway, the tank runs out of fuel and the engine stops. What is the next step? Refill the tank and bleed the air from the fuel system.
8. When you start the diesel engine, it turns over but does not start. What could be the cause? There is air in the fuel system.
9. What should you do if the speed of a diesel engine rises out of control? Stop the engine immediately by choking off its air supply.
10. The engine runs normally in neutral but stops when you engage ahead gear. What do you think has happened? A rope or plastic sheeting has fouled the propeller.
11. What is one of the conditions needed to start a diesel engine? The crankshaft must be turned fast by some means.

More Engineering topics

• Engine principles — 17 questions
• Engine parts — 16 questions
• Fuel system — 27 questions
• Lubrication and oil — 21 questions
• Cooling system — 18 questions
• Pumps — 11 questions
• Electrical system — 23 questions
• Propulsion and propeller — 15 questions
• Operating routine — 9 questions
• Safety and fire — 3 questions
• Calculations and units — 7 questions

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