When a Main Engine Piston Crown Gets Holed: Signs, Actions & Consequences

When a Main Engine Piston Crown Gets Holed: Signs, Actions & Consequences

By Abdullah M. Ferdaus Khan, CEng, CMarEng, FIMarEST

Vice-President, IMarEST Bangladesh

In the unforgiving world of marine engineering, few engine failures are as alarming—and potentially catastrophic—as a holed piston crown. The consequences, if not immediately recognized and managed, can escalate into a crankcase explosion, fire, or even complete engine breakdown.

This article outlines the primary indications, immediate actions, and further response protocols that engineering teams must undertake when a main engine piston crown gets holed during operation.

Primary Indications of a Holed Piston Crown

Early detection is key to preventing escalation. The following are common signs that may indicate a piston crown failure:

            • Activation of Piston Cooling Oil Non-Flow Alarm

            • Abnormal rise in Piston Cooling Oil Outlet Temperature, triggering high-temperature alarms.

            • Increase in Exhaust Gas Temperature for the affected unit compared to others

            • Engine Auto Slow Down initiated by piston cooling oil non-flow condition

            • High Oil Mist Alarm or noticeable increase in mist level detected by Oil Mist Detector

            • Auto Slow Down also triggered by high oil mist alarm to prevent crankcase explosion

            • Crankcase Pressure Rise, leading to lube oil leakage through crankcase relief doors and flywheel side seals

            • Sudden increase in Under Piston Scavenge Drain Tank Level based on the leakage severity

Immediate Actions by the Engine Room Team

Time is of the essence. When these symptoms are identified, the following steps must be taken immediately:

            1. Reduce engine RPM to Dead Slow Ahead to minimize damage

            2. Inform the Bridge and stop the engine if the vessel is not in a restricted navigation area

            3. Disconnect the unit’s fuel rack (set to zero) to prevent blowback or potential explosion through the piston cooling return line

            4. Monitor the Oil Mist Detector closely

            5. Keep personnel away from the crankcase doors and bottom platform to mitigate explosion risk

If Vessel Is in a Restricted Area

When operating in confined or restricted waters, the response must be balanced with navigational safety. In addition to the immediate engine room actions:

            • Bridge to notify nearby vessels, coordinate with local authorities, and request tug assistance if needed

            • Prepare both anchors on stand-by for immediate let-go

            • Continue cautiously at Dead Slow Ahead, only to reach a safe anchoring position

            • Advise the Master that no further engine movement is permitted after stopping due to oil accumulation risk, which could cause hydraulic compression and severe damage

            • Be aware of lube oil entering the exhaust manifold, possibly leading to fires or turbocharger failure

            • Closely monitor engine sounds and parameters for unusual behavior

            • Drop anchor and stop engine at the earliest safe opportunity

If Vessel Is in Open Sea

In deep-sea conditions, safety measures should be executed with minimal risk to maneuverability:

            • Immediately inform the Bridge and stop the engine

            • No further engine movement (start/stop) is allowed to avoid mechanical damage

            • Engage the turning gear and keep turning the engine slowly

            • Stop the lube oil pump, allowing both crankcase and scavenge spaces to cool

            • Do not open crankcase or scavenge doors until fully cooled and oil mist levels normalize.

Follow-up Actions and Precautions

Once the situation is stabilized, a systematic approach is required for inspection and recovery:

            • Inform Vessel Superintendent/Technical Manager without delay

            • Notify Class Society or Flag State as required

            • Begin thorough inspection, investigation, and repair

            • Conduct a Root Cause Analysis to identify the source of failure

            • Implement preventive measures to ensure such incidents do not recur

Final Thoughts

A holed piston crown is a high-risk engine casualty that demands immediate, informed, and coordinated response. Any delay or misjudgment may lead to a catastrophic engine room explosion, endangering lives, the vessel, and cargo.

Situational awareness, prompt communication with the bridge, and strict adherence to safety protocols are vital. The engine room team must remain calm, act swiftly, and always prioritize human and vessel safety above all else.

“Delay in actions may end up in catastrophe.”