Rebuilt engine = good thing?

[zAr]

If a listing says a diesel engine has been rebuilt and the prop shaft replaced, is this a good or bad thing? Is a rebuilt engine the same thing as a repowered engine?

Also, if an engine has been repowered/rebuilt, does that mean the engine hours are essentially reset and it's likely good for another decade or so?

And what could cause both the prop shaft and the engine to need to be redone?

[sailingdog]

A repowered boat can have either a new engine or a re-built one... the new engine is usually better... but it depends on who did the re-build.

[noelex77]

People advertising boats can sometimes be a little creative. If the engine has been rebuilt they should have receipts to show the work has been done. The cost will give you an idea of the extent of the rebuild.
A complete rebuild done correctly does essentially reset the clock, but the cost is close to the cost of a new engine and the labour to replace it, so it is rarely done. Even a "complete rebuild" will often leave periperal components such as the alternator untouched.
If the engine needed a rebuild prematurely make sure the cause of the engine problem has been addressed.

[WouldaShoulda]

Originally Posted by zAr

And what could cause both the prop shaft and the engine to need to be redone?

Running the boat aground or striking an object.

Gee, you mean the owner left that out??

[nk235]

When I bought my boat 2 years ago it was listed as having a rebuilt Yanmar 3GMD engine in 2005 and listed everything that was replaced/rebuilt which was every single thing except for one or two parts which were still to spec. I was also very skepticle because I know how people tend to get "creative."

However the previous owner of the boat was an engineer and mechanic and did the entire rebuild himself. I had diesel mechanics look at it and test it out and they were all very impressed at how well it ran and looked. Also the owner also installed everything from a dickson diesel heater to a top of the line windlass, new oven, radar with its own mast on the stern, awlgriped decks, refrigeration, and all his work was so precise and meticulous that it was easy to see why the engine ran so perfectly.

Still to this day two years later the engine runs like a top and I use the boat ALOT so if anything were to go because of the rebuild I think it would have went already.

So just adding my experience that I think it depends on who did it and what type of job they did. I think I got lucky that I had the best of both. I would suggest you have a proper mechanic test it out and find out who did a rebuild and why.

[Gramp34]

I looked at a boat a couple years ago advertised as having a rebuilt engine. What it turned out to be was an old engine that had been seized, but was unstuck by this owner without any new parts. For good measure he sprayed the engine with a can of bright orange paint, covering rust, dirt and leaking oil. He claimed, with a straight face, the engine was "rebuilt."

So unless the owner can show you complete receipts from a professional shop, it's not rebuilt.

If the engine has been professionally rebuilt, yes, it does mostly reset the clock. It's still an old engine so the boat's less valuable than one with a newer engine installed.

Keep in mind that the rebuild doesn't automatically add value to the boat. Probably he had a worn out engine that would make the boat unsellable, and the rebuild is just one of his maintenance costs.

The prop shaft normally isn't replaced unless it was damaged. It might have been scored at the stuffing box and wouldn't seal very well, or it was bent, or corroded, or something.

Good luck!

Tim

[Boasun]

A properly cared for Diesel engine will last for thousands of hours. That means using top quality lube oil, clean fuel and properly sized transmission and propellers.
Change the lube oil about every 250 hours or if you don't run the engine that much a season, then change the lube oil at the end of the season and do an internal wash. Don't let old oil sit in the engine over the winter. The solids in it will settle out and you will start having gunk in the engine, that will contaminate the new LO and that you don't want. Because the gunk will start wearing you engine away.
Watch your coolant also. Change it out as per manufacture's instructions because solids will start building up in there also.
So the bottom line is take care of that engine.

[zAr]

Plenty of good advice here, as usual. Thank you everyone for your input, you guys are great.

It didn't look like a rebuilt engine when I saw it, so yeah - I'm now asking where the work was done, why, and will want to see receipts.