Running dry for hours. .. what damage could have been done?

[SecondBase]

So this was running at the dock, at idle, and in neutral? If so it doesn't sound like conditions to overheat.

Heat of the moment and all but was the overheat alarm also ringing when he came back onboard? If the temp alarm didn't sound that forms another indicator towards "no-to-little" cylinder damage.

[danielamartindm]

Originally Posted by Kenomac

Oysters are routinely outfitted with water separators in the exhaust system, so you shouldn't see water and exhaust spitting from above the waterline. Only exhaust fumes from above and the exhaust cooling water comes out below the waterline.

Very alarming to most who're unfamiliar with this feature. Relax, your engine is fine. You just need a new starter motor, then buy a spare to include in your spares inventory. The black smoke inside your boat was from the burnt plasic on the starter motor.

Check with Oyster after sales department to verify your boat was equipped with separators for the engine and generator if unable to check yourself. If it was... maybe it's time to find a new mechanic.

Water AND exhaust visible above the waterline is a simple, instantaneous indication of a mixed cooling system working properly. Why build separators into the system that don't allow for a simple visual check of both exhaust gases AND cooling sea water? I'm just asking, was this a wise design?

[a64pilot]

Originally Posted by danielamartindm

Water AND exhaust visible above the waterline is a simple, instantaneous indication of a mixed cooling system working properly. Why build separators into the system that don't allow for a simple visual check of both exhaust gases AND cooling sea water? I'm just asking, was this a wise design?

If you separate the water, it reduces the noise considerably. A lot of your exhaust noise is water splash, of course separators do add costs and complexity. One day I will add a separator to my generator to help quieten it.
I assume this was the reason.

My personal belief is if it didn't overheat the coolant, the engine is unhurt, and I doubt at idle under no load that it overheated.
However the whole exhaust system may need replacing

[a64pilot]

Originally Posted by SailingFan

So how did the motor start itself?

Not a boat, but I was standing beside of an aircraft that the engine started turning over all by itself for no reason.
Being a turbine and no fuel was present it didn't start, but this will burn out the starter.
The reason was the 24V power to the aircraft clock ran in the same cannon plug, and right beside the starter relay wire, they shorted of course.
As I was the manufacturer, I had that wiring harness changed from then on.

For many reasons it's best that the bilge pumps be wired direct to the battery bank, but when you leave the boat for awhile maybe disconnecting the battery bank is best to prevent other unintended operation and fires?

[Privilege]

A simple indicator which might put your mind at ease will be to remove the cover on the raw water impeller. If the impeller is intact, then the likelihood is that it was pumping water and no harm has been done to the engine. If it's in pieces, then the engine almost certainly overheated and you can start to look for damage.

[Kenomac]

Originally Posted by danielamartindm

Water AND exhaust visible above the waterline is a simple, instantaneous indication of a mixed cooling system working properly. Why build separators into the system that don't allow for a simple visual check of both exhaust gases AND cooling sea water? I'm just asking, was this a wise design?

I works excellent, and doesn't sound like your boat's taking a leak everytime you run the engine or genset. Runs very quiet. There are other safeguards and alarms built into the system. Do you stand at the stern of your boat all the time watching to see if it's squirting water?

[boatpoker]

Originally Posted by Kenomac

I works excellent, and doesn't sound like your boat's taking a leak everytime you run the engine or genset. Runs very quiet. There are other safeguards and alarms built into the system. Do you stand at the stern of your boat all the time watching to see if it's squirting water?

Can't see the exhaust under the stern of our fantail so I put a 1/4" line from just before the muffler that exits on the topsides so I can see it from the pilot house.

Never seen a diesel that could get up to operating temperature let alone overheat at idle with no load. If you have a plastic muffler that might be an issue. You will certainly need a new impeller but I'd also be concerned about the bearings and shaft in the raw water pump

[Steve Bean]

How about a laboratory analysis of the engine oil?

[Kenomac]

How about a simple phone call to verify the existence of an exhaust separator?

[boatpoker]

Originally Posted by Steve Bean

How about a laboratory analysis of the engine oil?

Not worth a bean in this instance.
Oil Analysis .... Worth it ?

[boeing1]

did I miss something, I thought I read that he said the raw water sea cock was closed ?
can not believe it could of run for 5 hours with no raw water cooling.
valve had to be open.
yes very lucky boat did not catch fire

[Kenomac]

No, the knucklehead mechanic who obviously left the battery connected said he closed the seacock.

[transmitterdan]

If it ran for hours most likely it had cooling water. But check the impeller to be sure is good advice.

This problem (starters running continuously) is responsible for a few boat fires. Recently read a report of a boat fire caused by starter engaging when engine was running. Owner did not hear anything and was unaware until starter erupted in flames. Salt water is a tough environment for switches and connections. And salt makes a good conductor to bypass the start switch causing starter to run away.

[Kenomac]

I wonder if the OP is coming back? Don't you just luv it when someone asks a question, then does a vanishing act? Poof! They're gone.

[SecondBase]

Originally Posted by boatpoker

Not worth a bean in this instance.

Oil Analysis .... Worth it ?

Can you help me understand your reasoning? Wouldn't finding metal fragments of chromed cast iron wouldn't give insight into condition of the piston rings? Are you saying no baseline makes the oil analysis useless?