Hours on Detroit Diesel

[shallowskiff]

I am looking to buy a Hatteras and most have Detroit Diesels. 1980-1990 year models 58-70 ft.
How many hours before they wear out?
Is sea water intrusion the main cause of the engines needing to be replaced?
How do you prevent that?

Any model of DD that is on a do not buy list?

Would you buy a boat with 4000-5000 hours on the engines?

If the owner says they were overhauled and has receipts what do you look for?

Do I factor in replacing the engines into my offer price?


I am a newbie to yachts.

I am looking to use the boat going over to the Bahamas and on the ICW.

Also how many hours do you get out of the generators?

 

[Blowncar]

Okay, this a huge question that would take hours of typing to scratch the surface on. Your best bet is to join the boatdiesel website they have tons of info on Detroits. Here is a very quick stab at a few points.

Hours not as important as how they have been maintained. Sitting for years, unloved and ignored much worse than high hours on an engine that have been maintained and used.

High hp rated engines (based on per cubic inch) is bad bad bad.

You can try to get the price down but a knowledgeable seller who has his/her boat priced fair to begin with isnt going to knock off 60k or more if the engines run well because you are concerned at some point they may need a rebuild.

Many parts are cheap compared to other brands but some parts are very hard to find, those are $$.

A good set of engines if properly cared for, not run hard/hot, correct oil/oil changes, clean fuel and not overloaded can outlive you.

 

[Photolomy]

You should have a diesel mechanic survey the engines before you buy. Condition more important than hours, but 4000 or 5000 hours is getting up there. Don't forget the generator. They are quite expensive to replace as well. When I was looking at boats, the generators usually looked worse than the engines. One boat I looked at, and paid to have surveyed, had not been run for 3 to 4 years and didn't even make it through the sea trial. I was pretty upset that the seller didn't provide that information until after I paid $3k to have it surveyed. I was fortunate with the boat I did buy. The engines were factory rebuilt and the generator replaced in 2011. The seller was able to provide all of the receipts. On top of that, the mechanic that took care of her had worked on the boat almost since she was new (it was a single owner boat), and he provided all of the history.

As far as the engines, they should be clean, maintained and free of corrosion. Same for the generator. Do not get talked out of a sea trial of sufficient length to run the engines through their paces, including WOT. The performance should be by the book with respect to RPMs and temps. Watch for excessive smoke. New engines do not smoke. Not even when you start them up, unless it is really cold outside. It is best if you have an open and honest seller. If you know a Hatteras owner (who uses their boat regularly) take them with you on the sea trial. Even though you probably need a certified survey for insurance, nothing can beat a Hatteras owner/user to tell you what is wrong with a Hatteras.

There are many other systems that can add up in repair costs. AC for example. Deck issues. Toilets. But you are correct in focusing on the engine (and generator). And you shouldn't have to plan on a rebuild. Even that boat that failed its sea trial didn't need a rebuild. But it needed a lot of maintenance. The generator though was pretty corroded. It was the original Onan and probably would need to be replaced sooner than later, and that is around $18k.

 

[Briankinley2004]

There is a charter boat next to me that has 47,000 hours on its engines. As I type this they are 100 miles offshore fishing and run the boat almost daily. Only work inside the engines that has been done is valve adjustment. They change oil every 100 hours. They almost always idle or 10 knot the boat though turning it up on way in for the last few miles. Then there are boats around that only have a couple thousand being rebuilt. They usually sit and are not even cranked regularly. As said above hire a competent Detroit mechanic to check out. Troubshooting Marine Diesels by Peter Compton is a good knowledge base for what to look for and as Stated above boatdiesel.com.

 

[SKYCHENEY]

All advice above is good. Just remember, you may be able to afford to buy the boat, but not afford to own it. If you can't pay for complete overhauls(at some point, maybe sooner or maybe later), then you are looking at too much boat. You don't want to end up in that situation and it can happen even on a low hour, well maintained engine.

 

[Pascal]

Too many factors. It s not just the hours but which models DD (specifically the power rating vs displacement) as well as maintenance and probably most importantly how they were run. MY are often run at hull speed so higher hours may have been at low power aettings.

I would almost never spend money on surveys without first sea trialing the boat to make it is even worth surveying.

Generators can easily do 10-12000 hours without major work. I personally ran a pair of 18k Northern Lights that had over 9000 hours

Overhaul invoices should show detailed work and parts but even that is no guarantee the work was done right especially if it is a recent rebuilt

Asking price should reflect engine condition but of course some sellers are optimistic about their boat’s value. If the condition of the engines is below what hey should be then yes your offer should reflect that

 

[Photolomy]

I would almost never spend money on surveys without first sea trialing the boat to make it is even worth surveying.

That is a great idea, when it is possible, depending on location and scheduling. You would have to have two sea trials though, because the diesel mechanic will want to see the engines in action. The surveyor also.

 

[Pascal]

Yes but the first sea trial can be short. Pretty much just to check that everything is at least running. No need to spend money on surveyors only find out the has a massive vibration, engines overheat or genny doesn’t start.

I ve never had a seller refuse that clause hin en presenting an offer. It s pretty common. Only time I would skip that would be if I had solid history information on the boat.

 

[shallowskiff]

I appreciate the help.I am grateful for you guys sharing.What do you think about 12V-71 engines?Do they far into the to much horsepower vs cubic inches?

 

[Pascal]

I don’t recall the power ratings but they were not pushed very high. 550/600hp I think for 852 cid. Someone corrects me... down side is that being V12 a rebuilt is a lot more $$$ than an 8V71 or 8V92

 

[shallowskiff]

Broker is saying 650 hp.

 

[racclarkson@gmail.com]

Broker is saying 650 hp.

Those motors could have a pretty long life. Mine, for example, are rated for 840HP. Or...they could be toast if poorly maintained. Survey says...