Diesel engine hours

[Souvenir]

Just joined TrawlerForum yesterday... great site!

I'm starting to think about purchasing a Trawler, and know next to nothing about them at this point.* I currently have a 33-foot Cruisers Express.* I have in mind something in the range of 36 - 40 feet, single diesel.* Primary use would be week-long cruises on the TN River systems, and considering the loop at some point.

I don't know much about diesel engines yet.* As I'm looking at used boats, I'm looking at the engine hours.* In general,*at about how many hours would a typical diesel need to be re-built?* What is considered the reasonable lifetime of a diesel, in terms of hours?*

 

[AdamT]

I'm newish to trawlers too, but from what I gather diesel hours depend a lot on the specific model and of course on how it's been run and maintained. Generally they are much more durable than the gas engines we're used to. By way of example, a recent discussion about the old Lehman 120 suggested a typical rebuild interval of about 12,000 hours. Caterpillar suggests an interval of 30,000 hours for it's naturally aspirated 3208 model, but you have to discount somewhat for marine use. The best resource seems to be boatdiesel.com ($25 fee for full access).

 

[Souvenir]

OK. That's good information. I've looked at some boats advertised with engine hours as low as 1600 hours, up to maybe 4000 hours. Sounds like they are barely broke-in with those hours.

 

[Marin]

As Adam stated, diesels are much more robust than gas engines (except that lemon of a diesel GM made a number of years ago out of a gas V-8--- there are marinized versions of this engine around, avoid them like the plague).

There is a general feeling that modern, high-speed diesels don't have the service life of older or lower-speed diesels. I don't know if there is enough evidence yet to validate this.

Like any engine, a marine diesel that has sat idle for several years without being pickled, or has very low time on it for its age, may have problems that are waiting to happen. Diesels that have sat unused for long periods with dirty oil in them may have pitting of all the bearing and bushing surfaces that are immersed in the oil. Diesels that have been idled extensively, say for slow-speed trolling, may have problems including carbon buildup in the cylinders, fouled injectors, worn out clutch plates (in some kinds of transmisisons), etc.

There are generalizations about some diesels that are probably based on at least some truth, but should not automatically be assumed to be true with every example of the engine. The Cat 3208 Adam mentioned has a reputation of being somewhat trouble-prone. Cat six-cylinder engines from the late 80s and early 90s--- the 425 hp turbo model is one---- have less than steller reputations. But much of a particular engine's condition is based on how it has been operated and maintained. An engine that has had problems under very hard running and/or lax maintenance may be trouble-free for a more concientious owner.

Service life or time-between-overhauls (TBO) of marine diesels varies all over the map, but a VERY rough average could be 8,000 to 10,000 hours. The best thing to do, I think, is when you find a boat you are intersted in, talk to some reputable marine diesel shops in your area to get their estimate of the service life of that particular type of engine. The boatdiesel.com website is a good source of information. Also if a boat you become interested in is a fairly popular production boat like Grand Banks, CHB, Ocean Alexander, Willard, Marine Trader, etc., there will be at least one on-line owners group, most of which have no sign-up fee, where you can ask owners of similar boats about engines.

And when you find a boat you are seriously intersted in, NEVER buy it without having the boat and its engine(s) surveyed by a professional. Usually this involves hiring two surveyors, one for the boat itself and one for the engine(s). Surveyors tend to specialize in one or the other although there are some who do both. The engine surveyor we used when we were checking out the boat we eventually bought had a vast amount of experience with marine diesels including the type in our boat, and could not only judge the condition of the engines from the various tests he performed but also used sound, smell, and touch to reinforce his findings. A good surveyor is not cheap, but the money you spend on the survey can ensure your trawler experience is a good one, or it can save you from spending tens of thousands of dollars in unexpected*repairs.

You should have the surveyor take and submit an oil sample. Oil samples are more valuable as trend indicators over time, but a one-time sample can at least give a snapshot of what kinds of metals might be in the oil or if there is coolant in the oil, things that will give you and the surveyor an idea of the condition of the engine at the time.

Most marine diesels are vehicle or industrial engines that the manufacturer or a another company has marinized.* Which means adding the components necessary for the engine to be used in a boat.* This usually includes a raw-water cooled exhaust manifold, a raw water pump, heat exhangers for the lube oil, transmission fluid, and engine coolant, perhaps a larger alternator, etc.* The most common marine diesels are Cat, John Deere, Cummins, Lugger, Ford Lehman, Detroit, Perkins, Volvo,*and Yanmar.* There are others but these eight seem to be the most commonly encountered brands in trawler-type boats.

-- Edited by Marin at 13:52, 2008-02-13

 

[Marin]

The 10-10 rule probably makes sense in a commercial application. But a rough estimate commonly used for the average number of hours a recreational owner puts on a boat is 100 hours a year. Some do many more, some do much less. But at 100 hours a year, in ten years the engine(s) in the boat will have accumulated only 1,000 hours. Not enough time to warrant overhauling the typical marine diesel unless it was very high time to begin with and was starting to exhibit problems at the end of that last 1,000 hours.

 

[troy994719]

oldfishboat wrote:
Owners and brokers dont want you to operate the boat on sea trial at WOT for any amount of time. I dont agree with that .





I would make sure to open it up for a short period of time, If they just ease around at 1200 - 1500 RPM, you might not see any overheating issues.

 

[Marin]

Willy--- I agree with you regarding engine ancilliary equipment and the need to keep an eye on it. Leaks, rust, etc. has to be caught sooner rather than later, otherwise expensive damage to the engine core can occur as you point out.

And I wouldn't want to assume even a ten year life for things like the little oil and transmission fluid coolers, even the cupro-nickel ones.

On the other hand, it's not at all uncommon for the water-cooled exhaust manifold on an engine like the FL120 to last the life of the engine. There are FL120s out there with main engine heat exhchangers on them that are twenty or thirty years old, and inspections show no problems whatsoever. But this kind of thing will vary widely with the type of engine, how the engine is run, and so on. I expect the exhaust components on a higher speed, higher power, turbocharged engine will have shorter lives than the exhaust components of a low power, low speed, NA engine like the FL120.

 

[Jaxfishgyd]

I have the old standy 6-71 DD's natural motors.* Both where*100% rebuilt when I bought the boat in 2000.* You have to actually TRY in order to destroy these engines.
I change the oil every 100 hrs, change the radiator coolant every year and the raw water impellors also yearly. That's cheap insurance.
Adding turbos and the like will greatly reduce the time between being rebuilt.
I ave. 450 hrs a year and figure the motors will outlast me and I'm 57.
Now the amount of oil they drip is another story..... But oil pads are a lot cheaper than a rebuild..............

-- Edited by Jaxfishgyd at 19:15, 2008-02-13

 

[FF]

For a commercial operator the simple concept is an engine can only eat so much fuel before its worn out. So idf a boat has been used as a sport fish killer the block will be rated very high , turbo aftercooler and gulp 25 GPH..

The same basic engine in a "trawler" will run 2.5gph on its cruise and last at least 10X longer in terms of operating time.

I have NEVER seen a pleasure boat diesel worn out from use.
When I ran a yard I replaced dozens that were KILLED , by their owners thru mis use or lack of maint.

Diesels unhappily die when not in use , unlike a gas engine .

Put a car in a garage an 20 years later a battery and squirt down the carb and your underway.

IGNORE a diesel dockside for a year and the cylinders are rusted and pitted , lowering the compression and blowing white (low compression) smoke till a rebuild is done.
Do this year after year and its new engine time.

Diesels use very expensive parts , but are only different , not harder to work on.

A good diesel mechanic will frequently cost the price of a new gas engine , just for a major service. Torque the heads , adjust the valves and set the injectors .This can take 10 to 20 hours of moderatly skilled labor.Many diesels DO require special tools.

The lube oil and antifreez are different (more costly) and DAMAGE WILL occur if car stuff is used.

At 100hrs a year , most years , and 500hrs one time for the loop , why would you want diesel?* The second question is why chose an inshore boat with the shape of a trawler?

FF

-- Edited by FF at 04:37, 2008-02-14

 

[Souvenir]

Thanks for all the input - excellent information. I would definitely get a marine surveyor on board before I made a buy decision. I did that with my current boat, and it made me feel a lot better about the purchase.... and no problems to date.

I have a tendency to want to look at later-model boats; but given the longevity of diesel engines vs. gasoline, I should probably expand my search to include older boats. Most likely an older well-maintained boat would allow me to purchase larger and higher-quality within my budget.

Again, thanks for all the great information.

 

[Codger2]

Steve:* I've had 8 boats in a period of 13 years. Loved them all but it took that long for me to get it right. What does getting it right mean? Being totally honest with myself as to what <u>I'm really going to do with the boat.</u> At first I had images of cruising to Mexico, Central America, Catalina 5 times a year, etc. After about 11 years, my cruising looks like this. Lots of bay cruising with friends, Catalina once a year, offshore fishing (Tuna) twice a year, lots of days just puttering around on the boat and numerous times watching sporting events while in the slip. I didn't need a big boat or one with a lot of range as my longest leg is about 90 miles one way. A well maintained older boat (Diesel of course) is the way to go.
I've had new and used but used was a lot easier on the wallet, both buying and selling. GOOD LUCK TO YOU and* think about what you are <u>really </u>going to do with your boat.

Walt

 

[Souvenir]

Walt: Execellent advice.
We currently have a go-fast boat (Cruisers 33' Express).* We find that we almost NEVER drive it fast.* Seems that we use it as if it was a trawler; we're out there to enjoy the water, not interested in getting anywhere fast.

We take*a lot of weekend trips, but want to go farther.* Now that the kids are off to college, we have more time.

The general plan is to get a comfortable boat, do local 4-5 day trips mostly.* BUT, we seriously want to do the*Great Loop in a few years.***

I agree with what you're saying: don't buy too much boat for what we will actually be using it for.* Probably the answer is a compromise: slightly smaller than ideal for the Loop, but*adequate for short-range cruises.*

 

[Marin]

Steve---

There is a good piece of advice I've seen worded in a couple of ways. The way I learned it back in the 1960s was "buy the smallest boat you can afford." Which is to say that if you go for the smallest boat that will meet all your requirements, for x-amount of money you will get either a newer boat or a boat in better condition.

A surprisingly large number of people, I'm finding out, go for the largest boat their budget can accomodate. But unless they're buying new, they generally get a boat with a fair number of problems or potential problems. For example, a hundred and twenty grand can get you an older GB42 in fair to not-so-fair condition. The same amount of money can get you a really nice, older GB36. As long as the GB36 meets your requirements, it's the smarter way to go.

 

[Codger2]

Steve:

I <u>totally agree </u>with Marin's comments. As to the GB36, had I seen one before I bought my present boat I'd own one right now! An older gentleman in my marina has one and he does a lot of "predicted log" racing. I went with him on one outing and fell in love with the boat. (God, there are sooo many great boats out there it's <u>almost impossibl</u>e to get your mind around just one!)

Walt

 

[FF]

slightly smaller than ideal for the Loop

The Loop has been run in both directions by a jey ski, and many 16ft boats , less seaworthy than a 13ft Boston Whaler.

The World has BEEN CIRCUMNAVIGATED in 20 ft boats , and probably thousands of times in 30ish boats with a couple aboard.

Saefty dies not come from size , it comes from experience,
Comfort does not come from mere volume , it comes from an intelligent use of limited space , and a boat reliable enough that you can still sleep soundly , even if the bunk is not a walk around Queen.

30-35 ft or so is ideal,for 2, single screw will mean less weeks in the yard getting repairs, handyness (manners under power ) is required , as is good ground tackle and a windlass.

FF

 

[Dougcole]

Also, it is difficult to tell how accurate the hour meters really are. Mine, for example, were added aftermarket. I screwed up once when I was working on the low oil pressure alarms and left the key on on one of my motors for 5 days, so one shows a lot more hours than the other.

Useful for scheduled maintaince, but nothing else.

 

[Nomad Willy]

Well, it's obvious what Souvenir needs to know is ... how can I tell how good an engine is and how much longer will it last?. He's bound to be a bit confused as everybody talks about hours and he sees hour meters on most boats and then we tell him hours mean little or nothing. A case could be made for buying the boat with the most hours on it as one may infer that the engine was used most and therefore had less idle time to rust and corrode. One would need to know a boat didn't have 95% of it's hours in the 70s ... and sat after that. And then there is the old fuel tank issue. I'm in Alaska and decided a new engine and new fuel tanks were nessessary. Cost a lot but since I didn't buy the biggest boat in sight I was able to afford it. Correct me if I'm wrong but I think most trawler boats were built 30 or more years ago. A broker once told me the best boat deal that could be made is to buy a boat that had a series of owners that put money into the boat .. each with his preference .. engines, furnishings, glitter ( Awlgrip ect ), mechanical, electronics,hull ect ect untill the boat is a super boat but it's only worth as much as a 1982 Pudget Trawler ( or whatever ) is worth. Getting back to hours I think Souvenir should forget about it and put real effort into finding the best surveyor he can. Keep in mind that a surveyor can't tell if a 35 year old fuel tank is not going to start leaking next week. The engine however, can have fluid analysis, compression tests and other checks to determine how good it is and how long it will last.

Eric

 

[Marin]

Eric---

If you are including boats like Grand Banks in your definition of trawler boats, they still make them today although they now make only two models with the original configuration hull-- the GB46 and the GB52 and I'm not sure if they still offer the GB46. But up into the early 2000s, the GB36, 42, 46, and 52 were all in production and the upper three sizes were selling well. The GB32 was built up into the 1990s I believe. If not then, then the late 80s for sure.

I think you're correct in saying that many of the more popular makes of trawlers are from awhile back--- I'd say 20 to 30 years ago. But many of the brands-- Nordhavn, Krogen, etc.-- have continued right through to today and at least one of the old brands, CHB, has come back again.

 

[FF]

"Well, it's obvious what Souvenir needs to know is ... how can I tell how good an engine is and how much longer will it last?.


Well if he goes aboard and finds a complete service log , and a history of oil samples taken EVERY oil change for a decade or two.

If he finds a log of preservation , properly done , on layups the estimate will be EZ.

On my boat , I could hand it to him, as could any owner with commercial experience.

BUT, on most boats there is no such information.

So there are 2 choices.


Cheapest is to demand to inspect the vessel with out the engine being run in a couple of days.

Then its a matter of observing the start (the colder the OAT the better) and watching for white smoke, AND using a heat gun to take the engine block temperature.

Most diesels will smoke on start , from a quick puff , from a stream of white till the block is 160F. When the smoke STOPS on each model will give lots of info.

The electric injected newest engines are hardest , sometimes no smoke!!

Look in the bilge and see IF the owner was smart enough to use diesel lube oil.
Look for antifreez cans and see if diesel antifreez was used.

Second choice is to hire a mechanic and do a compression and blow down test , a surveyer won't have the slightest idea, a mechanic will.

Expect each engine* checked** to run over a GRAND for a good mechanic..




-- Edited by FF at 04:37, 2008-02-16

 

[Nomad Willy]

Hey Forum Fred,

Pardon my ignorance all to hail but what is diesel antifreeze. I didn't even know they made special AF for diesels. Why would one need it? Also whats OAT and how would one know by looking in the bilge that diesel lube oil was used?

Eric

 

[Jim Spence]

Eric,

Yes there is a special antifreeze for diesels. Engine manuf. each have their own recommendations. I think FF was talking about looking around for empty oil cans or oil used to top off the engine to see what kind the PO had used.

 

[Marin]

Eric---

There are antifreeze "mixtures" that are formulated specifically (or so the manufacturers claim) for diesel engines. The only one I am familiar with is sold under the Cat name (I don't know who actually makes it). According to our diesel shop, which uses and recommends it, Cat diesel antifreeze contains components that help prevent internal corrosion and other potential problems. Apparently, this is particularly helpful in a marine environment.

It used to be recommended that antifreeze be changed every couple of years no matter what. Our diesel shop---- and I presume many others--- no longer recommend this. Instead, they recommend having the antifreeze checked regularly to determine if it is still within specifications. If it is, don't change it. If it isn't, change it. This typically greatly extends the time between antifreeze changes, which considering its toxicity and difficulty to dispose of, is a Good Thing.

OAT is Outside Air Temperature.

 

[2bucks]

Here's more information than you want about OAT, IAT and HOAT. Context Marin, it's all about context.

Antifreeze is used in cooling systems to both lower the freeze point of water and
raise its boiling point. It is also used as a carrier for different types of additives
such as sodium silicate to protect aluminum from corrosion, anti-foaming agents
and other corrosion inhibitors. Although straight antifreeze actually freezes and
boils quicker than tap water, when mixed with water in the proper proportions (a
50% / 50% mix is ideal) in a cooling system, it greatly increases the cooling
system's ability to perform its designed function of removing heat from critical
engine parts and to enhance the service life of the various cooling system
components.
Inorganic Acid Technology (IAT) is the chemical composition for the traditional
antifreezes that are green in color. An IAT can be used with either ethylene glycol
(EG) or propylene glycol (PG). The normal IAT service life is two years or 30,000
miles (50,000 km).
Organic Acid Technology (OAT) was the first LLC / ELC introduced in North
America in 1994. OAT antifreeze had been widely used in Europe before its
introduction in North America. OAT can be either EG or PG but is mostly EG
based. Its first dye colors were orange and red. These dye colors are still used by
General Motors and Caterpillar. Green, pink and blue have been added to the list
of available OAT antifreezes. It is recommended that OAT not be mixed with any
other antifreeze technology. The normal OAT antifreeze service life is 5 years or
150,000 miles (250,000 km).
Hybrid Organic Acid Technology (HOAT) is a combination of IAT and OAT with
nitrites added. This makes HOAT suitable for use in both light duty and heavy
duty systems. Currently, two manufacturers are using HOAT for their vehicles.
Daimler/Chrysler's version is dyed orange and contains 10% recycled antifreeze.
Ford Motor Companys version is dyed yellow and does not contain any recycled
antifreeze. Both of these HOAT antifreezes use the marketing designator of GO-
5. They are compatible with each other but mixing them with IAT or OAT is not
recommended. The normal HOAT antifreeze service life is 5 years or 150,000
miles (250,000 km).
Nitrated Organic Acid Technology (NOAT) is an OAT with nitrates added. This
makes NOAT also suitable for use in both light duty and heavy duty systems.
NOAT and HOAT are very similar in performance characteristics. Currently, no
OEM vehicle manufacturer is using NOAT. The normal NOAT service life is 5
years or 150,000 miles (250,000 km).


Ken Buck

 

[Keith]

Lehmans don't need any special diesel antifreeze, just use a good quality automotive. I use the orange Dex-Cool myself.

Where you need the diesel antifreeze (or an additive that accomplishes the same thing) is for the wet liner diesels. The bubbles that can form impinge on the liner and can wear it out. Dry liner engines don't need anything special.

Or is it the other way around? I always get those two mixed up.

 

[2bucks]

The additives in "diesel" antifreeze are there to make the coolant flow over the metal and "adhere" to the metal. If there is not a close bond between the coolant and the metal when the metal expands slightly do to combustion, the concussion will allow the air molecule in the coolant to form a tiny air bubble on the metal. The forming and disolving of those bubbles over time will form pits in the metal, eventually eating thru. (if you're up on propeller cavitation theory it's a similar phenomenon)

Wet liners by design, are thinner than cast sleeve blocks. Therefore it takes much less pitting to cause a problem with them. Also being thicker, the cast sleeve block will form fewer bubbles.

Ken Buck

 

[Marin]

Ken--

Right but I think Eric was asking about FF's use of the term OAT in his post about observing the smoke that comes out of an exhaust on startup. I believe FF's point is that the colder the OAT (outside air temperature) the easier it will be to see and judge the smoke. I think FF has an aviation background or experience of some sort, and OAT is a commonly used term for outside air temperature in that field.

I could be wrong, but I believe that's how FF was using OAT.

 

[2bucks]

Ah hah! I see where that came from now. I started the session reading at Eric and Jims posts, they are talking only about AF and diesel antifreeze. Then you wrote two paragraphs on anti freeze and finished up with one sentence about Outside Air. My brain didn't follow the reply properly.

Ken

 

[FF]

"I think FF has an aviation background or experience of some sort, and OAT is a commonly used term for outside air temperature in that field."


Yup , Navy pilot and then a few decades with a major carrier. JFK based.

A DIESEL antifreez has SCA to help the cylinder walls last a bit longer.

SCA forms a slyme on the exterior of the cylinder and when the cyl rings like a bell (weather you here diesel knock or not) the cavitation is removed by the thickness of the slyme from the cylinder wall.

So the slyme gets the abuse of the cavitation, not the cylinder.

2 problems , the slyme coats everything , so periodically the Entire cooling system needs to be flushed and cleaned , or the general cooling will suffer.

The SCA has a limited life , so it needs to be replenished. Trucks that run high miles may need SCA , before a complete cooling system flush , so thete are antifreez test kits.

On a boat use the antifreez mfg change , or the engine mfg change sked , which ever is SHORTER.

We have a DD so the liners are in cast iron , so the SCA is not a problem , we use auto Prestone and ONLY!!! distilled water.

Its changed once a year when the boat is laid up for the season to be sure fresh antirust and water pump lube are in for next use.

The price of PM (preventive maint) is usually paid back 100 fold.

I expect as the high speed flyweight diesel car transplants /marinizatrions (Yanmar =Toyota land cruiser & BMW , or Mercedes Benz" become more common the PM may pay back 1000 to one.

 

[Codger2]

FF:* What did you fly in the Navy and did they use "shot gun starters" or were they cranked by hand?

 

[Nomad Willy]

Ken and Fred,

You guys are an incredible source of knoledge and I'm sure glad you're here. Don't go away as we will be needing you on a regular basis. My two diesel engine manufacturers, Yanmar and Mitsubishi, both recomend long life type AF but no mention of diesel application. Yanmar talked about aluminum and corrosion. I have no aluminum anywhere on my new Mitsubish, thankfully, and have Chevron AF long life and not the stuff for Catipillar. Would you recomend a change? The main reason I'm with Chevron is availibility in Alaska. I would hate to have my bubbles misbehaveing.

Eric