How Main Engine piston overheating may be judged and which corrective actions must be undertaken?
Piston overheating may quickly result in severe engine failure.
Overheating may be judged by:
- Increasing of piston cooling oil outlet temperature.
- Increasing the temperature of the cooling water at the outlet of the cylinder.
- Growing knocks in the cylinder at the end of each stroke. This may mean that the piston overheated and the teaser started.
Immidiate Actions:
- Immediately reduce the engine load and shut off the injection pump of this cylinder (lift the pusher over the fuel cam).
- Increase the supply of cylinder oil to the subject cylinder.
- If possible, stop the engine and wait for the cylinder and piston to cool while keep it turning with turning gear.
- Inspect the working surfaces of the piston, rings and cylinder liner.
- If necessary and possible, remove the piston.
- If the piston and cylinder liner are slightly damaged, correct the stuck points by grinding them with a carborundum stone.
- If the piston and cylinder liner are severely damaged, replace them with new ones. Before installing the piston, check the cylinder lubrication according to the manufacturer's instructions and clearances.
- If the repair or replacement of the piston and cylinder liner should be delayed and the sailing should be continued, then the piston complete with the connecting rod must be removed, as well as the stuffing box, must be sealed
Preventive actions
- Piston cooling medium (oil or water for some old engines) temperature and flow must be regularly monitored. Sensors regularly checked and calibrated to ensure proper functioning.
- During crankcase inspection pay attention to piston cooling oil drains. If debris and metal particles found accumulated in drain spaces/strainers the source of contamination must be immediately investigated. There are known issues with low-quality B&W cylinder heads. The low-quality material of those heads deteriorated and flushed out by cooling oil.
- At the time of cylinder unit overhaul, the piston must be disassembled and cooling passages inspected and cleaned.
