16 Years, 500 hr and new motor

[Kapn]

I saw a 12yr old boat with less than 200 hours on it get a new set of cylinder liners due to corrosion. I think it was a Cummins 8.3 450C.
The explanation was that there are always Some of the exhaust valves open when it comes to a stop, the salt air is always present in the exhaust pipe from the transom up to the engine. The oil sheen on the cylinder walls only stays in place for so long after shutting it down and the walls pitted badly. The turbos on that engine were also in need of replacing.
Then there are the items that should be done every 2-3 years anyways because they have salt in them. On that boat, the raw water pumps, heat exchangers, aftercoolers, oil coolers, were all beyond a simple cleaning. In the end, it would have been cheaper to do two new engines than piecemeal catching up on everything.

 

[firehoser75]

To the OP, Welcome aboard the forum and good luck with your boat search.
If I were you, I would ask lots of questions of the current owner, examine all maintenance records, logbooks, etc. to try to understand how this boat has been used and maintained. If you don't like the answers or he is not forthcoming, then walk.

I agree wholeheartedly with those who have stated that it is far worse for an engine to 'just sit" than to use it regularly. Overloading the engine (over propped) is also very hard on an engine.

As far as using a diesel engine under low RPM's and light load, most of what has been stated here (the response from Cummins excepted) is "old wives tales". Tony Athens (from Seaboard Marine (sbmar.com)), who is an engine expert with over 35 years experience, states that he has never seen an engine fail due to being operated under load at low RPM's. He states a better indication is how much fuel has flowed through the engine (burned). The more fuel, the more wear (all things being equal). So for example, 1000 hours at 2400 RPM creates more wear than 1000 hours at 1200 RPM (in theory).

Another boater I know, who has operated his Cummins 6BTA (2001) at low RPM since new now has almost 10,000 hours on it and it still runs very well. He does all of the necessary maintenance religiously.
Check out Tony's website, there is lots of good info there. In a nutshell, check out the exhaust for "doomed to fail" installation, regularly maintain the raw water components, change the oil as recommended, and give the engine good, clean fuel, and don't run it with no load at idle for long periods of time. Oh, yeah, and use it!
Again, Good Luck.