Why So Many Boats with Rebuilt / New Engines ?

[Chief Engineer]

The little known factoid is that having a new engine or rebuilt engine does not usually add to the value of a vessel.

[Captain Bill]

Originally Posted by headhertz

I think if I were designing a boat I would spec an air-cooled or closed-loop cooling system and solve half of my problems right there.

That probably only means that there is something significant that I don't understand and leads the actual designers to a different conclusion.

Thanks for the input.

I'm not exactly sure what you mean by closed loop. Most diesels these days are what I would call closed loop. That is the engine itself is cooled by a water antifreeze mixture just like a car, but instead of the coolant being cooled in a radiator it's cooled in a nice expensive bronze water to water heat exchanger. Instead of a fan to pull the air through a radiator it has a raw water pump to pump seawater through the heat exchanger. My sea water pump is about 4 inches square by 2 inches thick and the heat exchanger is about 10 inches long and 4 inches in diameter. A fan to pull air through an air cooled radiator would have to be much bigger. Even bigger than on a car because you don't have the advantage of 60 mph air flowing over the radiator for almost free at cruise speed. You would have to have a fan capable of pulling the air over the radiator at that speed to stop the engine from overheating or a very very big radiator. You would also have to have two opening in your boat big enough to move all that air through. If a boat used a truck type engine it would need openings as big as a Peterbilt grill. The last and most fun part is the effect of salt spray on the radiator. I grew up in a beach town in Florida with only 6000 people yet we supported three radiator shops that were always very busy. The salt spray from the ocean meant that most radiator corroded away in 2 to 3 years. I can only imagine what the direct spray kicked up by a boat would do to the fins of an air cooled radiator, but I'm guess it would last less than a year. Though they now make plastic radiator tanks, I think the fins are still metal.

I think this problem has been pretty well though through and the fresh water cooled diesel is the most efficient solution. The raw water cooled diesel is best in keeping with the KISS principal.

[headhertz]

Originally Posted by martinjrichter

From my experience ( 10 years over the road) most truck repairs are for stuff other than the basic engine, A/C units, alternators, water pumps and the like. Older engines often had injector and pressure pump problems, but with the new computerized units that is a thing of the past.

Your experience rhymes with mine. Half of my time as an auto mechanic was at Volvo dealerships and I never overhauled a Volvo engine that hadn't hydro-locked from having the intake of a running engine submerged in water. Water pumps, alternators, window motors, etc. Those are what kept me in business.

[Cheechako]

Originally Posted by martinjrichter

I owned a trucking company and had a Cummins 600 diesel 1850 ft Lbs torque. This same engine is used in quite a few power boats.

That engine would run 650,000 miles before a rebuild was needed. So I estimate that is 12,000 hours plus any idle time. Most long haul trucks idle 12 hrs a day while on the road, another 13100 hrs before the overhaul. Total 25,100 hr operating time.

From my experience ( 10 years over the road) most truck repairs are for stuff other than the basic engine, A/C units, alternators, water pumps and the like. Older engines often had injector and pressure pump problems, but with the new computerized units that is a thing of the past.

BTW Cummins specifies the oil changes at 20,000 miles or 3640 hrs intervals (13 gal oil and two filters). I just did it once a month when I went home.

This is right on. Unlike many boaters, I have never felt that idling a diesel engine to charge your batteries etc is an issue. You do need to get it up to operating temp though. Nor have I felt that it has to be run near max rpm. The reason Truck and Taxi diesels run so long is they never stop! When buying a boat, one with unusually low hours for the age may be the worst engine you can get.

[DeepFrz]

The little known factoid is that having a new engine or rebuilt engine does not usually add to the value of a vessel.

The word "rebuilt" means nothing to me. Many people will use that word and they have actually done very little work on the engine.

When I mentioned "maintenance" in an earlier post I meant it to encompass the fuel system, cooling system and exhaust system as well as the basic engine. Most problems with diesel engines are fuel related.

[David_Old_Jersey]

Engine location.

Out of sight, out of mind.........

[boatman61]

When you think how many boats have hit the market from the charter companies over the years are you surprised...
For five years they get abused and just enough maintainance to keep them going... usually in the 3000+ miles bracket... everythings just about shot and needing new parts...

[goboatingnow]

Modern small diesels in boats are derived from car engines, few such diesels will last over 130-150K miles without lots of rework, Theres a world of difference between high reving turbo diesels and large heavy industrial and truck engines.

Secondly diesel engine usage in boats is the exact opposite of what diesels want. Diesels like to be loaded up and run hot. Yet most boats requlary run them slow thinking that it prolongs the life. On the road, regulary rev change is good for diesels, prevents glazing etc.

Then there is the marine cooling system, a system that regulary overcools low speed operation, resulting in poor running and bore glasing. Often it also fails to cool high load high RPM usgae engines as well.

On top of that, the demands for high power, especially in planing motor boats, mean that many marinizers really push out the spec of the basic block with high compression, inter and after cooler ( and multi valve heads). The resulting engine now bears no resemblance to the original auto block and all sorts of trouble results, mostly because marinizers can in no way test like the auto companies do. ( who are the testers , you guessed it, you the boaters). A classic example is the Yanmar 24 valve 6 clyinder , derived from the ultra reliable nissan patrol, but fitted with 24 valve head, inters and afters, uprated turbos boost. Endless issues with this engine. ( there was a class action suit I beleive).

On top of that you regulary have owner servicing, rather then mechanic servcing.

And last of all as many have pointed out , marine diesels die from lack of use, if your buying a used engine, do not ,as many do buy a low hours engine on a old boat, unless the engine is new.

Dave

[mbianka]

IMO diesel engines and "sailboats" are a bad mix. My 1986 Westerbeke died after twenty years with only 1800 hours on it. A head gasket leak sprayed water on a cylinder head and cracked it. That was all she wrote. Sold the engine went to electric propulsion and have not had to squeeze my 6 foot two inch frame under the cockpit in four years to do maintenance and saved hundreds of dollars in maintenace costs too. I'm glad I made the switch but, then I do have a sailboat not a powerboat with sails.

[Chief Engineer]

What car engines are they?

Originally Posted by goboatingnow

Modern small diesels in boats are derived from car engines, few such diesels will last over 130-150K miles without lots of rework, Theres a world of difference between high reving turbo diesels and large heavy industrial and truck engines.

Secondly diesel engine usage in boats is the exact opposite of what diesels want. Diesels like to be loaded up and run hot. Yet most boats requlary run them slow thinking that it prolongs the life. On the road, regulary rev change is good for diesels, prevents glazing etc.

Then there is the marine cooling system, a system that regulary overcools low speed operation, resulting in poor running and bore glasing. Often it also fails to cool high load high RPM usgae engines as well.

On top of that, the demands for high power, especially in planing motor boats, mean that many marinizers really push out the spec of the basic block with high compression, inter and after cooler ( and multi valve heads). The resulting engine now bears no resemblance to the original auto block and all sorts of trouble results, mostly because marinizers can in no way test like the auto companies do. ( who are the testers , you guessed it, you the boaters). A classic example is the Yanmar 24 valve 6 clyinder , derived from the ultra reliable nissan patrol, but fitted with 24 valve head, inters and afters, uprated turbos boost. Endless issues with this engine. ( there was a class action suit I beleive).

On top of that you regulary have owner servicing, rather then mechanic servcing.

And last of all as many have pointed out , marine diesels die from lack of use, if your buying a used engine, do not ,as many do buy a low hours engine on a old boat, unless the engine is new.

Dave

I would like to know because I could probably get OEM engine parts cheaper.

[Rakuflames]

Originally Posted by Chief Engineer

What car engines are they?



I would like to know because I could probably get OEM engine parts cheaper.

I know two people who have actually had sailboats with Corvette engines in them, so the statement made sense to me. However, automotive parts in a seagoing boat might not be your best plan. Someone, with the best of intentions, encouraged me to get an automotive battery charger.

Then I had the new engine in, and the mechanic informs me that my bettery charger

COULD CORRODE MY BEAUTIFUL NEW ENGINE!!!

[goboatingnow]

I would like to know because I could probably get OEM engine parts cheaper.

Its not always possible, as many of teh big marinizers make subtle changes to key components. Volvo uses lots of Perkins blocks, but often changes head details etc. Equally because of different power speciifcations, things like heat treatment processess are different.

Sure you can source filters etc. But for main engine parts , unless you have access to OEM equipment lists ( which are never made available except i think Beta) you cant be sure what is the exact equivalent.

Dave

[ahnutts!]

I think it may be possible that some mechanics convince boat owners that their old motor should be replaced simply because its old. This happened to me, the mechanic came up with a dozen reasons why I should buy a new motor. "It could quit at any moment" and "Its really underpowered" being the best he could come up with.

I didn't buy it and I've put a lot of hours on that old motor since. I also found a new mechanic.

[Chief Engineer]

My question is what car engines are used?

There really isn't such a thing as a "Corvette" engine.....It is a General Motors Block

Unless you were posting in jest

Originally Posted by goboatingnow

Its not always possible, as many of teh big marinizers make subtle changes to key components. Volvo uses lots of Perkins blocks, but often changes head details etc. Equally because of different power speciifcations, things like heat treatment processess are different.

Sure you can source filters etc. But for main engine parts , unless you have access to OEM equipment lists ( which are never made available except i think Beta) you cant be sure what is the exact equivalent.

Dave

[sailorboy1]

Lots of times a "rebuild or overhauled" engine in a boat ad just means the injectors were serviced.

From an earlier thread it seemed people didn't really ever really rebuilt their engines. If it got to that point they replaced it.

Diesel engines that have a short life are mostly a result of the owner!