Class 2 (2nd Engineer) MEKM 📅 Oct 2025

Exam Question

(a) State, with reasons, the properties required for a cylinder lubricant for a main engine operating on HFO. (8)

(b) Describe, with the aid of a sketches, an electronically controlled cylinder lubrication system, stating how the timing and quantity of cylinder lubricant is regulated and set (8)

Reference Answer

(a) When a marine diesel engine operates on Heavy Fuel Oil (HFO), the cylinder lubricant must have specific properties to counteract the challenges posed by high sulfur content, combustion residues, and high temperatures. The key properties include:
1. High Base Number (BN) – 40 to 100 BN
Reason: HFO contains high sulfur (2.5-3.5%), which forms sulfuric acid (H₂SO₄) during combustion.
The lubricant must neutralize these acids to prevent corrosive wear of liners and rings.

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