The vessel had a four stroke main propulsion engine made by Akasaka Diesels, Ltd. of Japan. After discharging at a port, the vessel was about to set sail towards China for loading. The pre-departure checklist was completed and the Pilot boarded the vessel. The Engines were tried out and were on “Stand-by." The vessel started maneuvering and departed the coastal waters.
There was an alarm: “Main engine lube oil sump tank low level." I immediately asked the Oiler to sound the tank for the quantity. Before departure, the sounded quantity was approximately 10 tons and the oiler, after sounding the tank, reported that there was approximately a reduction of 5 tons. I reported the issue to the Second and Chief Engineer immediately and asked the Oiler to sound all tanks near the sump tank. I also called up the bridge and enquired about the visibility of any oil sheen on the sea. The bridge reported back that everything was normal and there were no traces of oil on the sea.
In the meantime, the oiler reported back that all other tank soundings were normal. We assumed that the change in sounding was due to the change in trim and draught of the vessel after discharging the cargo. In order to safely navigate out of the coastal waters, the Chief Engineer ordered topping-up the sump with approximately 3 tons of fresh lube oil. The Oiler sounded the quantity and reported that the final quantity was 8 tons.
As the Pilot disembarked, the vessel was ordered full away by gradually increasing the speed. To our surprise, again the “Main Engine Lube oil sump tank low level" alarm sounded. Now all the Engineers came down to the control room wondering what could be going wrong. The Oiler sounding the tank again reported that there was a reduction of approximately three tons and all other tank soundings were normal. We decided to stop the engine after informing the bridge.
We decided to open up the crankcase for inspecting the oil level through the grating. The Second Engineer ordered me to stop the lubricating oil pump and shut off the starting air. As I proceeded to stop the pumps, the Second Engineer went to open the crankcase.
After stopping the pumps, I went down to the bottom platform and suddenly saw huge quantities of lubricating oil flooding the engine room. The Second Engineer came rushing towards the stair case to climb up to a safer zone. After witnessing the reduction of oil flow, we both descended down to the bottom platform. As I looked into the crankcase, I found it to be flooded with lubricating oil. Now we realized that the oil did not “escape" anywhere, but was instead filling up inside the crankcase.