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Q1. A. Describe with the aid of a sketch, the arrangement of exhaust and air inlet passages in a medium speed four stroke engine cylinder head. B. With reference to [a] indicate where cracking might be expected stating the likely cause.  C. Explain the different factors that tend to cause distortion of 4stroke cylinder head. D. Explain how the effects described in [c] are minimized.

Q4. State how EACH of the following defects becomes apparent, describe its effect on engine operation or safety and indicate the corrective action required to restore normal engine condition;

A. Leaking air inlet and exhaust valves;            B. Leaking air start valve;

C. Cracked cylinder liner;                              D. Broken piston rings

Q7. A. State, with reasons, THREE properties required of crankcase oil which is to be used for a trunk piston main engine.

B. Explain how a representative sample of crankcase oil would be obtained from a trunk piston engine. C. Briefly describe the action to be taken if the crankcase oil charge cannot immediately be replaced and analysis shows – (i) Water is present; (ii) Alkalinity has fallen; (iii) Viscosity has changed appreciably; (iv) Carbon content has increased.

Q4. A. With reference to crankshaft and piston crowns outline the main stresses to which these parts are subjected. B. In each case explain how the stresses are generated and how they vary in magnitude and direction during one cycle. C. With respect to whole engine describe how stresses may be accommodated by good design and influenced by poor maintenance.

Q5. A. Describe using sketches a top end bearing arrangement designed to minimize or prevent the risk of oil film overload. B. Explain why successful lubrication of top end bearings is difficult to achieve in practice.

Q6. With Respect to main engine turbocharger;

A. Explain why cleanliness throughout the turbochargers system is critical to engine performance?

B. Describe in-service cleaning procedure for gas and air sides of a turbocharger indicating safety precautions to be observed?

Q7. In the case of main propulsion engine explain the indications and possible effects which might be expected from- A. Insufficient bearing clearances; B. Excessive bearing clearances; C. Crankshaft misalignment

Q8. (a) Values of some main engine exhaust temperatures displayed in the engine control room differ from those displayed on the engine for the same cylinders. (I) Explain how it may be determined which readings are inaccurate.  (ii) State possible reasons for these inaccurate readings. (ìii)Explain how the location of the faults may be detected. (b) State the periodic checks, which should be undertaken to ensure that remote engine instrumentation is reading accurately.

Q9. (a) Describe how it is determined whether a crankshaft was twisted during a major “smash up” in a main engine. (b) Explain where twisting is most likely to occur. (c) Specify with reasons the degree of twisting that might be accommodated without correction (d) Explain briefly what adjustments and precautions should be instituted when putting an engine with a twisted crankshaft back into service.