cylinder liner crack, scavenge, diesel engine, news, ocean, repair, piston,
crankshaft, vibration, stress, schedule, welding, machining, fitting, repairs,
fabrication, steel, tools, marine, engineer, engineering, equipment, machinery,
merchant shipping, sea, ocean, diesel engine, piston, liner
Gate Valve Problem
Stop Leak Completely
Heat stress can crack a liner
Checking the scavenging space
Cylinder head put back without piston
Cylinder Liner Crack
"We just have a scavenge fire in our main engine and now the cylinder liner is cracked!"
Bad news! We are in the middle of the ocean and we have a cylinder liner crack. The engine cannot be run long in this condition. The leaking water is finding its way into the lubricating oil. There is air lock in the cooling water and the temperatures cannot be maintained. The liner has to be changed. It is going to be a major repair job.
A check with the Captain says that the ship will be very much behind schedule if we were to change to a spare cylinder liner, something that the Company cannot afford.
The most logical step to take then is to isolate the faulty cylinder. It can be done.
Once that was decided, all the engine room personnel started their preparation. In addition to the tools normally used for dismantling piston and cylinder head, some special components like blanks have to be prepared to isolate compressed air, scavenging air, cylinder cooling water, piston cooling water, fuel valve cooling water, fuel oil, and cylinder lubrication oil from the rest of the engine.
The usual practice is to open up the cylinder head, remove the piston, and close back the cylinder head. All the passages that are connected to other parts of the engine will have to be blanked, so that the whole cylinder is completely isolated from the engine systems.
Since there is no piston in one of the cylinders of the engine, the crankshaft will be temporarily off-balanced. The engine has to be run at a much slower speed to avoid excessive vibration and unnecessary stress that can cause further damage.
The whole job probably took us about 3 to 4 hours. It's a temporary fix, but we are able to continue our journey to the next port of call. Meanwhile, the head office makes arrangements to provide the necessary shore repair specialist to help change the defective cylinder liner.
If the ship was not following such a tight schedule, probably, the ship's engine room staffs will have to change the cylinder liner themselves.