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Q6.  A completely new unit comprising piston, rings, liners, cylinder head and valves was fitted to a six-cylinder single-acting four-stroke diesel generator. Before installing the clearance and sizes were checked and considered satisfactory. During a trial run the running characteristics were abnormal so the generator was stopped. On examination, it was seen that the new piston had badly scored and drubbed the liner and had indication of seizure in the upper part of the liner. Give your reasoned comments for this failure.

Q3. State how each of the following practices affect piston ring life: (a) Nitriding of rings, (b) Chromium plating of ring grooves, (c) Contouring of rubbing faces, (d) Carbon or copper coating of rubbing faces.

Q4. Draw sectional diagram of the piston of 2-Stroke Diesel engine, marking each part. (8)

i) What is material of each part. (4)

ii) How many piston rings are in use, their type and material. (4)

Q5. a) Outline the problems associated with effective lubrication of the liner and piston assembly of a large slow speed engine. (6)

b) What are the causes of cloverleafing and micro seizure. (5)

c) Explain the composition of a cylinder oil suitable for an engine operating on residual fuel. (5)

Q5. With regards to modern 4-stroke diesel engine explain the following. a) The function of protection ring installed on the upper part of liner. b) The moderation in fuel injection drive system compared to conventional 4-stroke engine. c) Staggering of layout for multi hole nozzles. d) Effect of swirl and squish during the combustion process and how swirl and squish is generated.

Q9. If a main engine piston seizes in its liner at sea and it is not possible to replace the unit, explain, in detail, what provisions are made in the engine, to enable the ship to reach port?

Q1. A. As second engineer describe the procedure involved in the complete inspection of a cylinder liner and piston assembly, indicating areas of significant interest.

B. Explain with reasons, possible faults which might be found;

C. Suggest how such faults might be avoided.