How many hours before SMOH

[Wataworld]

I am curious about engine hours before SMOH

Brand Model HP Hours

And I would like alot of participation I think this would help figure cost and setup since hours to a motor is like a bank account the higher the account is the sooner you will need to spend on a SMOH
The same info would be valuable after a SMOH

Brand Model HP Hours

Thankyou all for the participation I will total the finding and report back
Gregg

 

[O C Diver]

Wow, huge amount of variables. Great deal will depend on how you use it and how you maintain it. Would guess most can go 10,000 to 20,000 hours when properly set up (correct prop pitch, correct gear reduction), properly maintained ( fluid changes, filter changes, valve adjustments, etc.), and properly sized for intended use (cruised at approximately 30 to 70% of rated output).

IMO, most of us who install a new engine won't run it enough to reach SMOH (not a whole lot of people in their 20s on this forum ). If you bought the boat used and there is 5,000+ hours on the engine, it's really hard to generalize life expectancy (of the engine ) without knowing how the previous owner REALLY took care of it.

Overhaul costs would be interesting to know, but will vary widely based on local labor rates.

Ted

 

[Nomad Willy]

Some people think it's a matter of hours. Like your bank account theory. But I know it's very rare for an engine to wear or deteriorate in that manner. Almost all die a slow death of abuse. Little things all add up I think. Like running hard out to the fishing grounds at heavy load and high speed and suddenly dumping the throttle to an idle to prepare for fishing. You're late so you run up to cruising speed with only several minutes of warm up. Put off oil changes. Frequently run for hours charging house batts. A broken coolant hose and the engine overheats but dosn't seize. For a period of time fuel finds it's way into the lube oil and you don't figure out what's happening until the lube oil is badly diluted. Over 20 or so years many of these things happen to pleasure boats.

These are the reasons engines become old engines having little to do with hours run or how many years the engine has been in service.

 

[mycows]

On my Cat 3116, they say 35,000 gallons.

 

[DavidM]

You are looking for some kind of correlation between engine model and hours to SMOH. I don't think there is one.

What you will find is that there is a good correlation between hp/per liter and hours SMOH. The high hp/liter motors, like the Yanmar BY series or the Steyr line, will succumb to all of the issues described by the previous posters early on in their life.

The venerable Lehman 120, Perkins 135, some Cummins and some JDs will keep chugging along almost forever due to their low hp per liter stress levels.

David

 

[Wataworld]

You are looking for some kind of correlation between engine model and hours to SMOH. I don't think there is one.

What you will find is that there is a good correlation between hp/per liter and hours SMOH. The high hp/liter motors, like the Yanmar BY series or the Steyr line, will succumb to all of the issues described by the previous posters early on in their life.

The venerable Lehman 120, Perkins 135, some Cummins and some JDs will keep chugging along almost forever due to their low hp per liter stress levels.

David

Yes this is exactly what I am looking for including the comments from before I understand it can be longer for some and shorter for other but both data will give an average it may also help us discover if a brand might be supperior or a specivic horsepower combo for an engine please keep posting but with answers even if you don't agree with my method or find it flawed i am just trying to get a corelation so say what you think but please post the data!
Gregg

 

[Phil Fill]

What is SMOH?

 

[hollywood8118]

What is SMOH?

since major over haul,
airplane term... not really the same in boats.

The original poster doesn't really grasp how boat engines are used
(and abused ), and how every boat engine.. and depending how it is set up will have different rebuild intervals and or life span.

Kind of like asking what does it cost to buy a house... too many variables.
HOLLYWOOD

 

[Vashon_Trawler]

What is SMOH?

I wasn't sure myself and had to look it up... "Since Major Overhaul".

 

[Nomad Willy]

There is the start stop cycles theory mentioned by someone recently here on TF. I believe good warm up and cool down procedures softens the impact of starts and stops considerably or even tremendously.

 

[O C Diver]

Yes this is exactly what I am looking for including the comments from before I understand it can be longer for some and shorter for other but both data will give an average it may also help us discover if a brand might be supperior or a specivic horsepower combo for an engine please keep posting but with answers even if you don't agree with my method or find it flawed i am just trying to get a corelation so say what you think but please post the data!
Gregg

Something else to consider:
Engine designs change more quickly now. By the time you have significant data on SMOH for an engine, the manufacturer has changed the engine increased the HP or changed where componets are built. In short, past performance isn't a guarantee of future results.

Finally, there is now a much wider selection of engines and HPs to better match the boats most of us have. As a result, and combined with the cost of fuel, one would have to think long and hard about repowering versus rebuilding to acheave better fuel economy. Nothing wrong with most of the classic trawler engines, but there are many I wouldn't rebuild with diesel at $4 a gallon.

Ted

 

[Baker]

And "marine age" also plays a part as well. Sometimes the age of the motor will cause it's demise...not the hours of use. There are certain accessories that age over time regardless of of usage/hours and can cause the early failure of engines...or at least increase wear. Aftercoolers, fuel coolers, heat exchangers all are subject to deterioration over time. And when they fail, they can cause significant issues.

To put it a different way....if you ran a diesel 5 hours a day on average you would get more hours out of an engine than if you only put 150 hours a year on it. And not because the old adage that "it is better for the to run than to sit.". It is because the hours acquired are over a short period of time where "marine age" is not such a factor....ie all the parts that fail due to age(not hours/use) are still relatively new so they provide good service.

 

[Wataworld]

since major over haul,
airplane term... not really the same in boats.

The original poster doesn't really grasp how boat engines are used
(and abused ), and how every boat engine.. and depending how it is set up will have different rebuild intervals and or life span.

Kind of like asking what does it cost to buy a house... too many variables.
HOLLYWOOD

Hi Hollywood
I do not think you can asertain my knowlege by my question! Answer the question and let the interpetation of the data speak for it self! As I shop for a trawler it is difficult to get these variables I dought seriously if any seller would tell the truth, oil analisys is great if the oil is used, compression can be played with, but all I am trying to find out if let say a lehman;s cost of ownership, versus a Cat, or a DD or a volvo which works better. It is fairly obvious under normal condition ie no blown radiator hose changed filters timely, air filters always on etc like Manyboats pointed out to understand a cat taxed with a higher HP (bigger turbo) would work how many less hours and Baker please limit your answers only to boat motors diesels in fact
Thanks Gregg

 

[Larry M]

Ford Lehman SP135, 7,929 hours. I should, if I last that long, go to 12-15K total hours, maybe more.

 

[AusCan]

Volvo MD17D
36 hp
2300 hours
29 years old
raw water cooled
No major mechanical work done yet as far as I am aware

No obvious issues, but I am more concerned with the 29 years old, than the 2300 hrs run.

 

[IntervaleII]

Regular oil analysis is a good thing to do to monitor issues and how everything is wearing. It also helps when selling.

Sent from my iPad using Trawler

 

[ranger58sb]

Perhaps a useful starting question might have been "How many people here who have owned a diesel engine have had a Major Overhaul done to that same engine?"

I have not.

-Chris

 

[Northern Spy]

It is fairly obvious under normal condition ie no blown radiator hose...

... please limit your answers only to boat motors diesels in fact

It is also fairly obvious that marine diesel engines do not have radiator hoses. Just saying.

Although I applaud your enthusiasm for acquiring mechanical nirvana; you are on a silly quest. But have at it. If you really want to try and choose your boat by empirical data, perhaps boatdiesel.com may be of interest. You may get lots of conversation, but it will still be merely opinion.

I assume you are buying recreational boat. There are no absolutes when it comes to past maintenance, operation or documentation of either. It is really more like buying a used car, albeit with a higher price tag.

 

[sunchaser]

I am curious about engine hours before SMOH
Gregg

How long is a piece of string you ask?

The answer lies in knowing these variables:

.. HP rating of engine
.. New or used engine
.. Prop setup and max WOT in gear RPM achieved
.. Normal cruise RPM planned
.. Knowledge and previous marine experience of owner
.. Capability of person doing maintenance
.. Adherence to book required maintenance
.. Hours per year put on engine
.. Year round use or lay up during winter months
.. Engine brand
.. Pictures of exhaust elbow area, especially where cooling water enters

Knowing the above information would provide a very good clue as to an answer regarding length of string.

 

[Codger2]

Hi Hollywood
I do not think you can asertain my knowlege by my question! Answer the question and let the interpetation of the data speak for it self!...... and Baker please limit your answers only to boat motors diesels in fact
Thanks Gregg

I'm sure with the tact and diplomacy you've displayed so far...that you will have a successful purchase. I'm not accustomed, however, to seeing a person ask a question and then telling a well intentioned member how to answer it!

 

[LaBomba]

I don't think there is an easy answer to this question either but if I were buying a boat I might ask how many hours do you think an engine can have on it before discounting it for purchase. This makes a very general assumption that an engine with 1000 hours like mine is better than one with 5000 hours which is likely but not necessarily true due to factors given by previous posters. My 1000 hour engine is 32 years old. The 5000 hour engine may be only 5 years old and have meticulous care and maintenance. You have to look at the specifics of each case but if I were buying a boat I would still want something with under 2500 hours just because that makes me comfortable.

 

[hollywood8118]

Hi Hollywood
I do not think you can asertain my knowlege by my question! Answer the question and let the interpetation of the data speak for it self! As I shop for a trawler it is difficult to get these variables I dought seriously if any seller would tell the truth, oil analisys is great if the oil is used, compression can be played with, but all I am trying to find out if let say a lehman;s cost of ownership, versus a Cat, or a DD or a volvo which works better. It is fairly obvious under normal condition ie no blown radiator hose changed filters timely, air filters always on etc like Manyboats pointed out to understand a cat taxed with a higher HP (bigger turbo) would work how many less hours and Baker please limit your answers only to boat motors diesels in fact
Thanks Gregg

Gregg,
you still don't get it do you...
if you asked about a specific motor.. or three for that matter you will get a answer. But to ask how many hours a diesel motor will go and what are the associated costs it is entirely too vague.

There are a LOT of different diesel marine engines .. and even more configurations of the same motor... I sometimes run a small passenger ferry that has " pumped" 8v92ta motors. They get about 2000 hours between " major" in frame rebuilds. There are a lot of minor things that break , water pumps, fuel pumps, cams, turbos, that go at different times during that 2000 hrs. Those motors in a yacht would last longer. The way these are run at max power all day, all summer.. 2000 hrs max.

Since you do not appear to be very familiar with marine diesels it would be a good idea to refer to the services of a well known marine mechanic if you get interested in a boat with a motor you know little about.
HOLLYWOOD

 

[Wataworld]

It has been suggested that my questions are too broad so I will be more specific I am talking about diesel motors that are often found in Trawlers like the members of this forum have, non commercial use. I will name the popular brands!
Volvo
Cat 3208 275 hp naturally aspirated
Cat 3208 375 hp turbo
DD 555
lehman sabre 135 HP
If I miss one or somebody has one that I did not mention please do not take it to heart and your input will be greatly appreciated!
I have not asked about cost of ownership because their are a lot of variables like taking it to the marina to change the oil or needing a mechanic to change a belt where others can do this them selfs
The purpose is like finding out if a lehman with 2500 hours is like a cat with 5000 hours this could be their half life, as I said I will be averaging out the data!
Thanks again
Gregg

 

[Baker]

.......and Baker please limit your answers only to boat motors diesels in fact
Thanks Gregg

Uhhhhhh...I was. What made you think otherwise????

 

[Baker]

Volvo
Cat 3208 275 hp naturally aspirated
Cat 3208 375 hp turbo
DD 555
lehman sabre 135 HP

Gregg

The Naturally aspirated Cat 3208 is 210hp..... Of the engines you listed, my first pick based on longevity alone would be the Lehman....followed by the NA Cat...followed by the TA Cat....followed by the Volvo...followed by the DD.

Others in no certain order:
Yanmar
Perkins
John Deere
Lugger
Cummins

 

[BruceK]

I cannot see how this helps, there are too many variables. Engines often die due to peripherals, rather than wearing out.
My 32yo Lehman 120s have just over 2000 hours. I expect they will outlive me. But, I recently learned (example of variables) one was pulled off its mounts when the shaft picked up a mooring float rope, in the hands of a PO. I just renewed the rear gearbox oil seal on that engine. Cause or coincidence?
I rate the Perkins 6354 as having similar properties to a 6.2L Lehman, and similar longevity. In either case a turbo version is a whole new ballgame.

 

[Baker]

In the end, and I think someone has already mentioned it, an engine that has the lowest horsepower per liter is likely gonna live the longest....all other things being equal.

You have a Lehman 120/135. And you have my Cummins at 330hp. They are almost exactly the same displacement(6.2 vs 5.9 respectively). I would expect almost 2.5 times the hours out of the Lehman than the Cummins.

Somebody mentioned rating an engine based on how many gallons have been run through it. Same thing since fuel/heat/energy pretty much equals horsepower.

 

[Andy G]

.........And just to confuse you Wataworld, I have managed to kill two Lehman 120's in 15 years, a feat many thought impossible, just imagine what I would have done to a less reliable engine.

It reminds me when my old mutt Basil, an Old English Sheep dog, ran straight into a fully grown tree, having not noticed it. I said to a lady standing next to me, as by way of an explanation, well he's adorable but not the sharpest knife in the block. She looked straight at me and said, sheep dogs are quite intelligent, it's the owners who tend to be the problem.

Moral of the story, it's not the engine type you need to worry about but the PO's.

 

[Sailor of Fortune]

It has been suggested that my questions are too broad so I will be more specific I am talking about diesel motors that are often found in Trawlers like the members of this forum have, non commercial use. I will name the popular brands!
Volvo
Cat 3208 275 hp naturally aspirated
Cat 3208 375 hp turbo
DD 555
lehman sabre 135 HP
If I miss one or somebody has one that I did not mention please do not take it to heart and your input will be greatly appreciated!
I have not asked about cost of ownership because their are a lot of variables like taking it to the marina to change the oil or needing a mechanic to change a belt where others can do this them selfs
The purpose is like finding out if a lehman with 2500 hours is like a cat with 5000 hours this could be their half life, as I said I will be averaging out the data!
Thanks again
Gregg

I think you probably mean the Cummins 555 and DD 6-71

 

[Bay Pelican]

To step back and try and take a different approach when buying a used boat:

Oil analysis of the engine for what wear is on the engine. If the oil is fresh avoid the boat as you can't tell what, if anything, is being hidden.

Oil analysis of the transmission.

Age of the the marine add ons Both water pumps, the heat exchange, alternator, the exhaust elbow.

Last time the drive plate, if any, was changed.

Turbo condition, if any.

Last time the engine had a valve job.

Whether the engine is a higher performance to weight engine especially the higher rpm engines. (Yanmars versus Lehmans, Volvos and Luggers)

When were the hoses replaced?

With this information a good marine engine surveyor can give a reasonable opinion on the condition of the engine and the add ons.

Hours of use and age are not alone the important factors.

Marty