diesel engine use

[fairtide]

I have a feeling that there will be lots of responses and references to past discussions of this nature, but what the heck, as I am still undecided and need some fresh ideas about what really is good for our diesels, regardless of manufacturer. I'm asking about loading of the engine and what we seem to think that means.
Many of us will state that diesel engines fare best when they are run between 80 and 90 of their full loads, as established by the manufacturer. Usually, this is expressed as a range of engine RPMs, and we assume that the transmission is in forward and that a suitable prop is spinning. If all goes as it should, the engine will have a load that is acceptable. We know that our engines can run all day at these loads, and that is good for them. Running at trolling speeds (engine RPMs near idle without trolling valves) all day seems to be bad for the engines, as they are not loaded to that accepted level.

Okay, take a nice big diesel engine and put it in a truck (tractor). The engine load is high while accelerating and going up grades. Once moving on a flat road, that 12 liter power plant uses less fuel per hour than many of our boats while properly loaded and pushing us through the water at about 15 kts. The truck engine has a good percentage of its running hours with loads that are not as high as what we boaters seem to think is best for our engines. Boats don't go downhill for long, so our engines do not get a rest until we reduce fuel and speed. I don't think that diesels in trucks run for long periods of time at RPMs that are 10% lower than their red lines.

So, I would like to know how your engines have fared, maintenance-wise. Have those of us who clock hours at low speeds had more engine problems than those who run mostly at what is called cruising speed? I expect to read lots of comments about engine temperature, carbon buildup, and turbo sludge.

I do put the 28TE on plane for about a fourth of the time that I am just doodling around on the river. I don't run faster than 3000 RPM. The bulk of the engine time is run at about 1500 RPM. With a tad over 200 hours on the clock, I am in for some problem?

[DougSea]

Others who know more than me will chime in but I have three comments...

Trucks - ever listen to one shift? Their transmissions are very different beasts than boats and I believe they in fact ARE running in their crusing zone more than you might think.

Construction equipment - I use a diesel powered skid-steer at our yacht club for spring and fall mooring and dock launching. When you sit down in there and get set to go to work the first thing you do is advance the throttle to full...and there it stays all day long (regulated - not really flat out)

Generators - we also have a diesel generator at the club (it's on an island - pretty cool place, http://www.spriteisland.com) and we make sure when it's running that we put enough load on it that it's working hard. Probably not at a full 80 percent load wise although the RPM's are obviously constant. People always look at me funny when I tell them to stop turning off lights when they leave a room! She's been going strong for 1000's of hours with only minor maintenance.

Anyway, just a few data points for you. Looking forward to the discussion!

[RicM]

If you really want endless bloviating on this topic a subscription to boatdiesel.com will cure what ails you. My quick synopsis of the issues is...
Overload-Bad
Overpropping, often done by OC's trying to get the last bit of forward motion out of a teaspoon of diesel fuel results in rapid engine destruction, especially in lightweight, high RPM, high output diesels of which the Yanmar 6lp 300 & 315 are prime examples. These engines are often described by troglodyte DD enthusiasts on boatdiesel.com as "hand grenades". Ignore them, they will all be dead soon and then they will (perhaps) shut up.

Under loading - not so bad
Trolling for hours at a time, like 8 hours a day, all day, will lead to carbon build up. Run it fast and the carbon she go away. You gotta get to where you troll, then you gotta get home. Get there at 3000rpm and she be fine. Add some Lucas diesel treatment if you are anal compulsive, cheaper than a Valium.

Under use - most likely bad thing you will do
The day your pretty little 6LP gets bolted into your TE it, like you, is a day closer to it's demise. Run it hard, run it often, don't worry so much and you will both live a longer and happier life. Diesels are the engine of choice to do long distance, heavy work, in the worst conditions day after day for a reason. They are tough, strong and love to run. If you really want to worry, buy a boat with a pair of gas fueled Crusaders. You' save about $30k and find out what misery is all about.

[fairtide]

I did a bit of looking around on line for diesel duty cycle information and found a site that many of us may want to take a look at. Afterward, we may have more posts to the question in this thread.

http://sbmar.com/Articles/Continuous-Duty.php

[RicM]

Tony Athens is the owner/operator of the boatdiesel.com website that I recommend above, and knows more about sick and broken diesel engines than just about anyone in the world. I have read thousands of Tony's words, including a slightly different version of the article linked here, and I believe that every one of them is true. That said, if you want to become one of Tony's disciples (and they are legion on boatdiesel.com) you will spend many of your waking hours obsessing about fuel filtration ( 3 times is not enough!), marketing claims (lies all lies!), salt water corrosion (it's everywhere!), to the point that you will have a hard time enjoying your boat and like many others feel compelled to spend long hours in your basement, online, on boatdiesel.com and The Hull Truth involved in flame wars about whether 2 cycle or 4 cycle diesels are the real saviours of men's souls and modern civilization.

Don't get me wrong, I was on the ICW in May, bringing a 1947 Trumpy with a pair of DD 671's from Charlestown to Norfolk when we had some issues in one engine. I posted on boatdiesel.com and within an hour had half a dozen good, informed helpful answers. It's a great site. Understand however, that Tony spends his days in the dark bilges of the sick and dying, which may give a certain bleak slant to his attitude. The thousands or millions of smooth running boats and happy owners out there on the waterways do not feed Tony and put his kids through college, it's the disasters, rotted cooling systems, blown heads and burnt pistons that do. He is honestly and truthfully trying to help you avoid these situations, but remember the avoidance of ALL risk means little fun.

Everyone has their own level of comfort and detail when it comes to engine maintainence. I know I was a bit freaked out by my first real expensive diesel engine (my MB 240D in 1982 didn't really count). I got over it. Do your best to take good care of your gear, but things break. You will spend money fixing stuff on a boat. That's life.

[RobS]

What Ric said.
And having a Yanmar under the hood, you will seldom log-off of BD smiling.

[jleonard]

I have been a boatdiisel member for over 10 years and a Tony Athens fan. He helped me immensly when I did my Mainship repower in 1999 (wow that long ago alreay?).
Multistage filtration saved me on my current Albin with the 120 Lehman. No ther way to go IMO.
Regarding corrosion, I always did my raw water maintenance...impeller every 2 seasons, clean the coolers every 3 or 4 (all will be removed this fall and cleaned,painted, etc)
Never had a heat problem and I don't fret about overheating.
And this is all with single diesels.
Be smart about it and the engine will last.
Right now (knock on teak) I have 3800+ on the Lehman and it is running good.

[RicM]

I can't disagree. I have learned a ton from boatdiesel.com, and it all boils down to one thing. You pay a certain amount of money to pump water from the front of your boat to the the back of your boat. You can do it faster or slower, but the net result is aproximately the same. Someone with OCD should do a study. I will bet that the cents per gallons pumped will be about equal no matter what rig you use to do it. A gallon of diesel fuel contains X amount of energy. Your rig determines how much of that energy gets transferred into transportation and how much is wasted as heat. Diesel fuel contains more energy than just about any other liquid fuel source, Diesel = 129,500 BTU/gal, more than jet fuel. Jet fuel is lighter.

[Veebyes2]

We all get our share of problems with our boar diesels. They work hard. Think of a boat engine as spending its entire life going up hill pulling a very heavy trailer. The faster we want to go the steeper the hill, the more the water resisitance.

By contrast my 6.6L Duramax (Isusu engine, really) truck pulling our approx 14,000lb 5th wheel seldom has to do any real work. It purrs along at about 17-1800RPM in 6th gear doing about 62MPH. It seldom gets over 2500RPM. Thats where it shifts gears if the load is not great. It gets used every day.

The poor boat engine on the other hand at best sits all week doing nothing then gets run hard on the weekend. Worse, it sits for months with no use at all.

[glk34]

Ric, I really like the twin crusader gas engine comment. I would not be able to boat if I had to run those and maintain them.

Iron Jack