Main Engine Overheat on Passage with Restricted Port Options
Your coastal vessel is on passage with a 6-cylinder four-stroke main engine rated 1,200 kW at 900 rpm, driving a fixed-pitch propeller through a reduction gear. Two hours out, the exhaust gas temperature on No. 4 cylinder rises from 380 C to 470 C while the others hold near 385 C. Lube oil pressure is steady at 4.2 bar, cooling water outlet is normal, and turbocharger boost is unchanged. Fuel is the same batch used since departure. The nearest suitable anchorage is 3 hours away; the next port with repair facilities is 9 hours away. Wind is force 5 on the beam and the forecast shows it freshening. The chief engineer is ashore and you are the senior engineer on watch.
1. Interpret the temperature anomaly and decide what immediate actions you would take before choosing a destination.
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A single-cylinder exhaust temperature rise of about 90 C with stable boost, lube pressure and cooling water points away from a global air or cooling fault and toward a cylinder-specific problem: a faulty or dribbling fuel injector, a partially seized or worn exhaust valve, or a fuel delivery issue on that unit. The unchanged turbocharger boost argues against an air-side restriction affecting all cylinders.
Immediate actions:
- Reduce load progressively to lower thermal stress on No. 4 while keeping steerage way.
- Compare the cylinder's exhaust temperature with its previous trend and check for smoke colour, knocking, and fuel rack position if accessible.
- Verify the temperature reading is genuine by cross-checking a second indication or an infrared reading on the branch pipe.
- Record all readings with times in the engine log and inform the master of the situation and the options.
Do not continue at full power to the distant port with an unexplained hot cylinder; the risk of valve or piston damage rises quickly.
2. Compare proceeding to the 3-hour anchorage against the 9-hour repair port, and state the criteria you would use.
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The decision turns on whether the fault can be safely contained at reduced load and whether repair capability exists at each option.
Anchorage option:
- Advantages: short exposure, sheltered water for investigation, ability to open up the cylinder or change an injector at anchor.
- Disadvantages: no shore repair support, weather forecast freshening may make anchor work uncomfortable, and a failed valve cannot be fixed there.
Repair port option:
- Advantages: spare parts, machining, and technical support.
- Disadvantages: 9 hours at sea, possibly at reduced power, with a deteriorating weather picture and a known hot cylinder.
Criteria to apply:
- Can the engine be run at a load where No. 4 stays within, say, 30 C of the others?
- Is there a spare injector and the tools and crew to change it?
- What is the weather trend and the vessel's ability to maintain safe speed and course?
- What does the master require for schedule and safety?
A reasonable judgement is to run at reduced load toward the anchorage, attempt an injector change there, and only proceed to the repair port if the fault persists or cannot be isolated.
3. State what records and notifications you would make, and how you would hand over to the chief engineer.
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Record in the engine log and a defect note: time the anomaly was first seen, all cylinder exhaust temperatures, boost, lube oil pressure, cooling water temperatures, load changes made, and any investigation results. Note fuel batch and injector running hours if known.
Notify the master in writing or by a clear log entry, including the options considered and the decision made. If the company has a reporting procedure for machinery defects, raise it so the shore technical department is aware before arrival.
Handover to the chief engineer should state plainly: the symptom and its trend, what was done, the current operating limit, what spares are on board, the destination decision and its rationale, and what remains to be investigated. Avoid conclusions not supported by the readings; present the evidence and the open questions so the chief can make an informed call.