In early July, I came to my boat after being away for three week and found the engine seized. It was locked up solidly, in that it would not budge even a little bit after soaking the cylinders with Marvel Mystery oil for several days. It turned out to be a blown head gasket which let salt water into a cylinder.
I hauled the engine out with the boom and rebuilt it for a cost of only parts and machine shop work. The engine is back in and is working great. I have posted photos online if anyone is interested.
Yanmar 2QM15 Rebuild - a set on Flickr (www.flickr.com/photos/dreuge/sets/72157631067396554/ )
Unless you live near a Yanmar distributer, knowing which part numbers to order can be time consuming and costly. I include my list below in order that it may help someone down the road.
My total cost was about $825.
Machine shop work
Cylinder head work $300
Honing piston rod bushings to fit piston pins $40
YANMAR 2QM15 PARTS
Price quote from Mastry Engine Center
head gasket (124060-01331) [$28.79]
valve cover gasket, o-ring type bonnet (124060-11311) [$8.47]
oil pan sump gasket (124060-01743) [$16.26]
exhaust manifold output gasket (124701-11911) [$9.15]
exhaust manifold Adj. gasket (124770-13131) [$1.87]
exhaust flange gasket (124770-13171) [$27.43]
engine zinc cover gasket (124450-11681) [$1.53]
thermostat gasket (104211-49160) [$1.36]
exhaust manifold forward flange gasket (124770-13181) [$9.00]
piston rod bearings (124060-23300) [2@$13.38]
piston w/ rings (724060-22722) [2@$86.37]
piston pin bush (124060-23910) [2@$5.08]
cylinder liner (724070-01900) [1@$111.77]
zinc (27210-200300) [2@$3.60]
zinc packing (23414-250000) [2@$0.85]
thermostat (124770-49200) [1@ 27.10]
Lubriplate #105 assemble lube
(coating piston, rings, piston pins, bearings) ~$7
Copper Cote gasket spray
(for head gasket and copper exhaust gaskets) ~$5
Permatex form-a-gasket #2
(gasket dressing for other gaskets and hoses) ~$4