With obvious factors considered such as the rpm the engine was primarily run at, load, yada yada...what do you all generally consider the tired point for the various common marine diesels. I feel around 10K you're basically on the verge of a rebuild...wrong? I feel like you could definitely get more years out of one but how many. I'm in the used boat market and considering my options price wise but if a rebuild is looming than it's all for not in some ways...I wish I could afford to buy "the right boat" I'm not afraid to do the work on the boat but I just get so many mixed reviews in terms of engine life that I figured I'd throw it out on here and try and gain a little more perspective.
The best way to determine a tired engine as an owner is the following:
1- Does it use oil, there is an acceptable allowable amount of oil consumption to fuel consumption for every diesel engine manufacturer out there, so based off of your model and make, the engine manufacturer can provide this for you to compare against.
2- Does the engine have a lot of oil leaks due to high crankcase pressure, high crankcase pressure is usually a good indication of the following.
a. worn cylinders and piston rings or ring lands
b. worn valve guides and seals
c. turbo charger seal leakage
3- Does the engine start hard, does it crank over longer before firing and when it does, does it stumble and misfire for a few moments while blowing a lot of smoke all over the harbor until it builds a little heat to increase compression? When under way does it knock and stumble a little until fully up to temperature?
4- Does it start only with Ether in cold weather, does it need ether in warm weather? Low compression worn out engine will cause this.
5- Does it not make all of the rated engine speed that it did when new? Does it smoke blue smoke when loaded at higher engine speeds constantly?
6- Is it plugging or fouling oil and oil filters, does oil pressure fluctuate when hot and when cold? High soot content is an indication of carbon and combustion gas leaking by the piston rings and the oil is encapsulating the soot and gases causing early oil breakdown and heavy soot retention. Oil sample is a great tool for understanding engine life. I recommend if you are concerned to start with oil analysis, do it over the period of 3 oil changes to get a trend and a baseline. Take a sample of the oil you use when new to start and than you have a base engine sample and the additive package to compare against the oil breakdown and metallic wear that the oil and filter are trapping along with soot, coolant or fuel.
Just my 2 cents as Bill D would say FWIW.
These are basic symptoms of an engine that is really showing age.
Peter