One thing, in my experience at least a marine diesel, or at least a 12 cylinder EMD will run for several hours on low engine oil levels. Once it gets shut down however there’s no restarting it till after the overhaul.
The engine techs said that damage indicated the sump oil levels were below the crankshaft.
Low levels or low pressure? Or you mean low enough levels to affect the pump suction / pressure or temperatures?
A low oil level is a signal to go check it on the stick to confirm that, not immediately shut down the engine. Many ways to go from there like add oil, check is it low due to normal consumption or is the loss big and unexpected, is there an external leak? Did someone forget to lock the drain valve closed? Did someone fit a spinner filter and connect it with hoses that are hidden below the deck plates and never get inspected and got hard and deteriorated and blew out and pumped “a bit” of oil out of the sump? There may be additional clues as you head down the ladder, like sickening smell or low oil pressure alarms or possibly shut down. Such is life.
On an EMD the oil level is always below the crankshaft. The p-pipes deliver oil to the piston crown “shaker” area for cooling and to lubricate the wrist pin bearing, thence to the cylinder and down to the sump.
Story developing, the pictures of the main bearings and the possibly discolored crankshaft journals with bearing material metal transfer, I would wager will never be open to public viewing. I would like to see the parts list they think will be required for the repair of the vessel.
If the crankshaft DOES get into the oil, it foams it up and makes a big mess of frothy oil that does not lubricate very well nor pump well. You do NOT want this.
If you have an oil temperature gauge, you can see oil temperature rise if there is not enough oil present but enough so that the engine is not pumping air.
The pistons, rings, liners, and rods, comes as preassembled “powerpacks.” They are relatively quick and simple to change. No need to remove the sump or engine mounts.
I have only seen a catastrophic EMD failure once. Several rods came right out through the side of the block. That they had a lube oil pressure failure but kept running the engine was obvious. It did a lot of damage to the crank, but did not break it. I don’t know how or if it was fixed. I doubt it. I may have heard that the boat was eventually scrapped.
I ran EMD for a lot of years. Even an idiot like me can’t destroy one. . . .I often wonder what some folks do with these engines. . . .the Power Packs are a great idea. Of course changing the “fork” packs are easier than the “blades”. Just keep feeding them fuel and lube oil and they will keep running. . . .
Most of the tugs that I sailed on had EMD’s. Some of the older ones had re-purposed Rail Engines. With those you had to make sure that they changed the oil pan out. If they left the original pan, you could lose oil pressure in mild seas.
When sailing on large ATB’s, I would raise the oil level whenever bad weather was expected as you pitch a lot more with an ATB in either a head or following sea. It took some experimenting to find the correct level because as was pointed out, if you overfill too much all it does it leak out of the read main.
A failure that I witnessed on a medium speed diesel was caused by failing to correctly torque the bottom end of one unit. To gain access to the crankcase door on one side of the engine a local control panel had to be removed. At survey under the previous owners the engineer had fashioned a spanner, which was later found, and removed the big end bearing for inspection working from one side of the unit only.
The result, a new crankshaft, an expensive rebuild and legal action.
In my 39 years in the business, probably 15% was spent chasing down and repairing junk in the garden spots of South America and West Africa. Most of my time was with EMDs. I’ve experienced many piston, liner, carrier, head failures but only one rod bearing failure.
Around '89, the company was rotating out the tugs from various divisions for overhauls. I reported aboard in Corpus to a recently dry docked and overhauled tug. 400 hrs on the overhaul. On the trip over to Tampa with a loaded barge, 900 RPM with floating .84 rack, the PME started lugging. I took the PME control and slowly lowered the throttle. As I was about to shut it down, the rod came through the hand hole cover. The scoring on the crankshaft had me highly concerned.
On arrival in Tampa, we were met by ABS, the company that overhauled, the engine parts supplier, VP of engineering and a machinist for the crankshaft repair.
It was quickly observed that the failure was caused by a mismatched bearing. They were all happy to find the simple cause. I was amazed the machinist declared the journal could be polished out and still use standard inserts. The VP of engineering declared “You highly talented professionals figured this out in short order. Has it occurred to you that if you have one mismatched bearing, you have at least one more?” The look on their faces was priceless.
I sailed on this tug for 12 years. The first 4 were challenging with the piss-poor rebuilt engine components.