The frequency of piston drawing-out check varies according to the daily maintenance, especially the lubricating oil control and load (overload and excessively low load). Therefore, the supervisor is required to decide the proper frequency. However, the initial overhaul and check should be performed at the time mentioned in maintenance manual which is around 8000- 10000 running hours. From then on, decide the subsequent check schedule according to the overhaul checking results, an increase of blow-by and an increase in lubricating oil consumption. When the lubricating oil consumption has become twice the initial value, overhaul and clean the piston, and replace the piston rings.
- Make sure the all stand by auxiliary engines are ready.
- Read the manual and have a tool box meeting with everyone involved in the job. Discuss the complete procedure.
- Prepare important tools and spares required for overhauling liner as given in the manual
- Prepare risk assessment and make sure all personal safety equipment are used
- Go through the previous records/manual for clearance and adjustments
- Put the display card “MEN AT WORK”, “DON’T START” at lub oil pump and auxiliary engine breaker.
- Close air bottle valve to auxiliary engine and engine start and stop valve
- See that the turning bar is not in the flywheel and should be in place
- Open the indicator cocks.
- Close lube oil, fuel oil, fresh water inlet/outlet valve, drain the cooling water line and remove connections
- When drawing out the piston, cover the crankshaft with a sheet or the like to prevent water and foreign matters from entering the crankcase.
- Screw the lifting eyebolt into the piston, and lift it by 20 to 30 mm.
- Loosen the connecting rod bolts with the specified disassembling tool, and then remove the bolts and metal cap.
- Set the piston at a position of about 30° after the T.D.C.
- Eliminate the carbon from the upper part of cylinder liner.
- Remove the disassembling tools and protection ring.
- Set the piston at a position of about 80 to 90° before the T.D.C.
- Prepare the tools as per the manual.
- Place the protection ring drawing out tool 1 on the piston.
- Place the tool so that its outer taper faces toward the piston and do not allow it to make contact with the cylinder liner.
- Attach the liner retaining implement 2 and spacer3, and lock them with the cylinder head tightening nut.
- Turn the flywheel, and remove the protection ring.
- Remove the upper metal, and draw out the piston.