Interesting engine partly seized story

[crown22]

I visit my boat once a week since I bought it two years ago and I always turn it over by hand to move the oil around.
Today the engine wouldn't turn as easily as normal and needed considerable force to turn it over with a socket and bar on the crankshaft pulley nut.
Fearing the worst I operated the starter motor and it fired the engine after about twenty seconds.I had turned off the cooling water seacock.
Seacock then open and the engine performs perfectly pumping water idling and coming up to temperature as usual with the oil pressure
warning light off and no smoke or unusual noises.Oil level shows as correct on the dipstick and no loss of coolant.If I had tried to use the starter first without turning it over by hand I think that it was tight enough to damage the starter or ring gear.Lombardini 702M Any explanations gratefully received

 

[lw395]

I would guess that water evaporating from the exhaust system condenses on the cylinder walls of whichever cylinder has its exhaust valve open.
Eventually a ring rusts to the bore.
When I know the engine will be unused for months, I disconnect and dry the exhaust.
Otherwise I crank the engine decompressed at least once a fortnight, this is enough to hopefully throw some oil onto the lower bore and move it around with the piston. I want to see the oil light go out.
If you've only been turning over by hand, then I doubt the oil gets to the bores?
As you caught it fairly soon, I doubt any real damage was done.

 

[crown22]

Thanks LW that sounds like a great explanation.My boat is more floating caravan than boat so I suppose there is some truth in the idea of engines suffering through lack of use? I can't decompress my engine.My engine has a cast iron block
so rust seems possible.Its only done 444 hours from new and only 30 hours last year.I suppose the answer is to start it
every fortnight or so.Thanks again

 

[Spirit (of Glenans)]

Start it every fortnight and run it for 20-30 minutes, in gear and at about1800-2000 rpm. Diesel engines prefer to be run under load, idling is a recipe for glazing the bores.
Car engines wear out from high mileage, boat engines expire from underuse.

 

[Charlie Boy]

As Spirit of Glenans says, run it long enough to get it warm when you fire it up otherwise condensate will form and cause corrosion

 

[lw395]

Or 'winterise' the engine properly with the exhaust dry.
It's not much work.