Thinking about Diesel's

D

dantheman

Member
May 17, 2009
102
Rochester NY
Boat Info
1989 390 Express
Engines
454's
I'm looking at boat with 8v92's in it and was wondering what are the specific things to look for in a diesel, any help would be great, (i never new a diesel could be a 2 stroke) I do have a diesel in my truck, so I'm not completly new to them. thanks..
 
With 2 stroke Detroits, don't even consider buying them without a full mechanical survey. Detroits are known to need a top end overhaul fairly early.......some as early as 1500 hours, others run longer. The gotcha on rebuilding them is that these engines are no longer produced and rebuilding has gotten expensive if you need to do it. A few years ago you could have the rebuild done for about $1500/cylinder; now, its closer to $5-$6000/cylinder.

Other then the obvious older technology, Detroits tend to leak and smoke but they are powerful and very sound engines.
 
I think you will enjoy diesels but a few things I would keep in mind.

1) Like Frank said, I would have a survey done on any Diesel. You may miss something obvious, and you can learn a great deal about the particular engine if you can spend time with the surveyor.

2)Increase your cash reserves. I am not joking. I don't care what diesel brand you end up with, repairs are not cheap. 2 Examples-2005 580DB with 800HP Mans limped in to my marina after being sent there by a Sea Ray dealer who couldn't service Mans. Salon was taken apart so transmission could get moved away from the engine and some engine seals, etc. were replaced. Guy was stranded for 2 weeks before he was stuck with a huge bill for the repair and another for the marina stay. Another Sea Ray left the harbor and returned quickly being followed by a cloud of black smoke. He ordered a replacement Mitsubishi Turbo for his Detroit and it cost him $6,500 for the turbo not including labor and overnight shipping. In both cases you could have practically bought a Mercury factor rebuilt engine for the same cost!

3) Service: Before you buy a particular brand, check with available service in your area. Being in NY you may have tons of places, but where I boat whenever you see the Michigan Cat truck in the parking lot it brings tears to your eyes. They begin to charge when they leave their house in the morning and turn off the meter when they return to their driveway. My Detroit/MTU dealer is about 100 yards from my boat.

Hope this helps.
 
Frank / Cruisinguy,
Thanks very much for the replies, I really appreciate that.. guess ya can get into a bad situation if something goes wrong, 5-6 grand a cylinder? I could almost get a new 454 installed for that much, geez.. Still, I'd like a 50 footer someday, but probably a little newer, say 2000, but not before doing a lot more homework, thanks again.
 
At 5-6 grand * 8 cylinders = $40k to $48k.... that's a hell of a 454! I'm in a similar situation though - starting some research now on my next boat. The diesel vs. gas question is the first one I'm trying to solve as the size I'm looking at can be had with both.
 
Don't get me wrong, I would choose a diesel every time in a larger boat application and you can go years without an issue. I only have about 800 hours on my engines but other than some warranty work early on, this was the first year I have had to touch them. Had to replace an injector and a valve. Haven't received the bill yet!

Travis, if the boat you want is offered with both, I would take them out for a test. I have been on a 38' Cruisers with gas and thought it was really nice and than the same boat with Yanmar Diesels and the Yanmars were absolutely awesome on that boat. Fast and very fuel efficient. It was an extremely expensive option when new, but on the used market the price difference wasn't too bad.

I re-read by post earlier and the 58DB actually had 1050 Mans.
 
I am of the same mind. In fact, I'm looking for a trailerable inboard center console now that I can repower to a diesel. I just don't see another gas boat of any kind in my future.

For most people moving up to the sized boat where diesels become available, the mechanical risk is something they have never had to deal with before. But risk is manageable. You do it by realizing that the buyer is responsible for his own due diligence on a prospective purchase. Don't believe anything a seller, broker or salesman tells you until you confirm it in some way. Ask for and review the service records on a boat. (the absence of a service record is a clue to the previous owner's attentino to mechanical details) Do enough research to know what and when scheduled maintenance on the engines was required. Spend the money for both a hull survey and mechanical survey of the engines done by a factory authorized technician.

Do those things and there is probably less mechanical risk with diesels than with gas engines.
 
"mechanical survey of the engines done by a factory authorized technician."

I made this mistake and it cost me. The Hull Surveyor did my Diesel survey and although he was very knowledgable, he didnt know the details of my specific engine. I had the a cummins certified tech, actually got the owner of my local cummins dealer, provide a captains breifing after i bought the boat. He picked up about $ 8000.00 in minor issues that i could have negotiated with the seller.
 
I've just gotta know, what kind of minor issues cost 8k? 8 large doesn't seem too minor to me. :huh:
 
I know a little about diesels, but my good buddy Eric is a diesel mechanic, and a good one. When another buddy told Eric he was looking at a boat with the Detroit V8 2 stroke diesels, Eric came unglued about how crappy that engine is.

I bought a boat I really liked last fall knowing that it had notoriously bad engines in it, but they ran good and had good compression. Now one year later I have put 1400 into the engines. I plan to repower this Winter.
 
Go to boatdiesel.com if you are considering diesels. A boatload of info and knowledge over there [sorry, couldn't resist].
Diesels are much less forgiving or missed maintenance than gas engines. If you survey them by a qualified tech and they check out OK, you will like them IF you are a maintenance Nazi. Otherwise, get big blocks or a smaller boat.
 
Newbie said:
I've just gotta know, what kind of minor issues cost 8k? 8 large doesn't seem too minor to me. :huh:
Click to expand...

He picked up the raw water pump seal with rust indicating a seal failure, defective thermostats on one motor, fuel cooler expanded ( he removed hoses and inspected), transmission oil leak on the hydraulic pump. He knew what to look into on these motors. Also some of it was maintenance, valve adjustment, after cooler servicing/cleaning, all which should have been done on my motors, had about 380 hours. Yeah general oil changes and filters were done, but none of the recommended services. These are all minor issues but they do add up. Knowing this before i closed i probably would have negotiated some of this work.

My point is that the manufacturer's reps know what to look for on their engines. THey have service history and understand possible areas of failures to look at.
 
Before you go drinking Pascoe's Kool-Aid, you need to add to his list the question about the quality of your investment with diesels vs. gas engines. Diesels don't depreciate like gas powered boats do. A 10 year old Sea Ray with diesels retains a lot of its original value and frequently sells for near the same money as when they were new. You are lucky to find a buyer for a 10 year old gas boat.

Also, understand that we are talking about a very few or narrow group of potential models that fall into the size category where there is even a choice between fuel types. Generally, nothing over 44 ft can be bought with gas motors and nothing under 35 ft has a realistic diesel option.
 
I was on a local dive boat yesterday. A 1981 36 footer with a single DD 2 cycle 300HP NA motor. We had 12 POB and TONS of dive gear. He ran the boat at ~1800 RPMs and we made ~10knots. The motor has just over 7800 hours and ran well. When he started her up in the morning....No smoke....when we headed out the inlet No smoke. A tad loud, but that's probably more a boat design then anything else. He runs the boat all year round and doesn't winterize anything. When it get's down to 10 deg F, he said he drops in a 100W light bulb into the ER.
 
fwebster said:
Before you go drinking Pascoe's Kool-Aid, you need to add to his list the question about the quality of your investment with diesels vs. gas engines. Diesels don't depreciate like gas powered boats do. A 10 year old Sea Ray with diesels retains a lot of its original value and frequently sells for near the same money as when they were new. You are lucky to find a buyer for a 10 year old gas boat.

Also, understand that we are talking about a very few or narrow group of potential models that fall into the size category where there is even a choice between fuel types. Generally, nothing over 44 ft can be bought with gas motors and nothing under 35 ft has a realistic diesel option.
Click to expand...

I believe he has this one backward - twice. The lower the HP/CID ratio, the longer the life, not the opposite as he writes.

"Conversely, divide the CID by the horse power, and the greater the result UNDER the factor of one (1), the longer engine life you can expect. If you have an engine with an 0.70 CID/HP ratio, then you can expect 3000 hours engine life. Otherwise, you are a victim of the myth."
 
Hampton said:
I believe he has this one backward - twice. The lower the HP/CID ratio, the longer the life, not the opposite as he writes.

"Conversely, divide the CID by the horse power, and the greater the result UNDER the factor of one (1), the longer engine life you can expect. If you have an engine with an 0.70 CID/HP ratio, then you can expect 3000 hours engine life. Otherwise, you are a victim of the myth."
Click to expand...

Hampton is correct on this, the lower the HP to cubic inch ratio, the longer the engine life. My engines are 636 cubic inches but only make 355 horsepower. That means it is not working hard to produce that HP so the lifetime less strain translates into into longer life.
 
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Here I am, merrily reading along about this guy's question and BOOM, you poke me in the eye with a sharp stick. Ban gas motors...ha...
 
docofthebay said:
Hampton is correct on this, the lower the HP to cubic inch ratio, the longer the engine life. My engines are 636 cubic inches but only make 355 horsepower. That means it is not working hard to produce that HP so the lifetime less strain translates into into longer life.
Click to expand...

Same with my 3126's...350HP on those engines is barely using their potential.
 
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