Engine Life

Tony B · Feb 13, 2012

I am still actively trying to sell my sailboat and get a trawler. Hopefully, soon it will sell.

Buying a 2nd hand boat doesn't always afford the luxury of what type of engine you get with it. having said that, here is my question:

Many motor yachts have twin gas engines in the 250 to 350HP range.

Many mid-1980's boats have around 1200 to 1500 hours on them. Assuming they were exposed to an average amount of maintenance, are these engines still considered young or are the ready to die? Everything has an expected life span, so what is it for gas engines?

Thanks in advance.

psneeld · Feb 13, 2012

Tony B wrote:
I am still actively trying to sell my sailboat and get a trawler. Hopefully, soon it will sell.

Buying a 2nd hand boat doesn't always afford the luxury of what type of engine you get with it. having said that, here is my question:

Many motor yachts have twin gas engines in the 250 to 350HP range.

Many mid-1980's boats have around 1200 to 1500 hours on them. Assuming they were exposed to an average amount of maintenance, are these engines still considered young or are the ready to die? Everything has an expected life span, so what is it for gas engines?

Thanks in advance.

Approaching 4000 hours/10 years*or so (maybe way more)*on the assistance towing boat 454 cu in engine*I run....beat the crap out of it all year....including runnning it at least 10 hours a season with the high temp alarm buzzing and towing or pulling a boat off a sandbar. Engine oil changes every 200 hours or after a day of running it well overtemp.* Once ran it at full throttle for 2 hrs at 1000 rpm less than rated rpm cause I was pulling a barge against a 5 knot current, at night*in the middle of a Nor'easter.* The alternative was being dragged backwards over the breaking bar (for a lot of the time I WAS being drug backwards!)

No telling how long they may last these days...but babying engines seems to kill them sooner...

-- Edited by psneeld on Monday 13th of February 2012 02:58:32 PM

bnoft · Feb 13, 2012

I don't pretend to be an engine expert but I would feel comfortable with a "reasonably" maintained diesel with 1500 hours but not a gasoline engine with similar hours. The Cummins in Amazing Grace have clocked about 2200 hours and I expect them to carry on.

Larry M · Feb 13, 2012

We had a 1966*Chis-craft*with Chevy engine that needed to be rebuilt* at*~3500 hours.* The mechanic who did the rebuild, who knew how we ran*the boat,*said that it was time.

Gas engines are cheap.* You can get a 5.7L (350 cid) remanufactured long block assembly off the self for under $3,500 or complete for ~$8,000 with a full system closed cooling system (with manifolds).

BruceK · Feb 13, 2012

Hi TonyB,

Hopefully your trawler will have one or more diesels. 1200-1500 hours* is nothing, provided they have been looked after. Often peripheral bolted on parts fail or rust away before the engine itself. 10,000 hours is not unusual on diesel hire cruisers in frequent use (a bit like gas engines in taxis doing high miles because of less cold start wear), same would apply to fishing trawlers. Turbocharged engines,less common on trawlers, may not last as long, turbos wear out, and can cause engine problems if they let go.

My 30 year old Ford Lehman 120s have done 1900 hrs, run well, use very little oil.Some engines have better longevity than others, slow revving diesels are usually long lasting and surprisingly economical, despite large cubic capacity.

BruceK

Marin · Feb 13, 2012

Tony B wrote:
Many mid-1980's boats have around 1200 to 1500 hours on them. Assuming they were exposed to an average amount of maintenance, are these engines still considered young or are the ready to die? Everything has an expected life span, so what is it for gas engines?

That's a bit like the "how long is*a piece of string" question.* The only gas engines I've had experience with are vehicle, aircraft, and outboards.* In my opinion, the life of an engine--- any engine, gas or diesel--- is largely if not totally dependent upon how it is operated and maintained.

I know a lot of people believe in running an engine hard.* "It's good for 'em" is the reasoning given.* I don't subscribe to this at all.* I've mentioned this before in other discussions but the best engine person I've ever known was Bob Munro, one of the founders of Kenmore Air Harbor and the person who ran it from 1946 to 2000.* He was a terrific pilot but he was an even more terrific engine mechanic.

I asked him one day what I as a pilot could to do maximize the life of the 450 hp radial engines in the Beavers that I've been flying since 1980.* He said, "A piston only goes up and down so many times.* So the easier you make life for the engine, the longer that piston will go up and down."

By this he did not mean to baby an engine or run it at power settings that were too low.* And he was not trying to say that a piston has a specific number of cycles before it will fail.* Only that if you treat an engine properly, it will treat you properly.* He was a big proponent of operating an engine in the lower part of it's proper operating range.* And he definitely did not agree with the notion that running an engine hard is "good for it."* Be it the gas engines in his seaplanes or the Cat diesels in his old steel-hulled deFever.

He went on to tell me some specifics about how to make life easier (and longer) on the Beaver's engine, but the same philosophy applies, in my opinon, to any engine.* We run and maintain the FL120s in our boat as though it was 1960, not 2012, for example.* And I think it pays off in terms of engine longevity.* I've had sufficient very*long-term experience with specific vehicles and planes to convince me of this to my satisfaction.

So I don't think it's so much how many hours are on the gas engines in the boats you are interested in, but how the engine was treated during those hours.* That same number of hours could mean an engine is nearing the end of it's useful life, or it may mean that it has many hours of operation left in it.* It will all depend on how the previous operator(s) treated it.* So try t find out how the engines were operated and maintained by the previous owners.* Gas engines may be cheaper to replace than diesels, but I don't view that as a rationale to treat them as throw-away engines.

BTW, as Kenmore Air added turbines to its fleet---"stinky things" as Bob called them--- he had his basic "make life easy on it" philsophy extended to them, too, a practice that continues to this day.* And it has paid off big time for them in terms of the service life they get out of them, in some cases almost half again the life and definitely a fraction of the problems*other seaplane operators with the same planes and turbines are experiencing.

(I took the attached photo during one of my wife and my trips to SE Alaska in the late 1990s.* The plane was built in the 1950s, the engine during WWII.)

-- Edited by Marin on Monday 13th of February 2012 10:46:11 PM

markpierce · Feb 13, 2012

Was told my engine will outlast me.

Giggitoni · Feb 13, 2012

If you think of a gasoline engine in terms of what we would expect in a car or light truck, the following may apply:

1,500 hours at an average speed of 45 miles per hour (city + highway) equates to about 67,500 odometer miles. Mid-life?

Marin · Feb 13, 2012

Giggitoni wrote:
1,500 hours at an average speed of 45 miles per hour (city + highway) equates to about 67,500 odometer miles. Mid-life?

I currently have 246,000+ miles on the original engine in my BMW 635csi and it's still going strong.* Gas engines*can last a long time if you run them right

FF · Feb 14, 2012

The service life on any engine really depends on its operational use.

When you hear of diesels with 10,000 hours between rebuilds , you can be sure they were not infrequently used yacht engines.

Light them off , load to 80% and your industrial diesel will do great long term service.

BUT in a boat the problem with diesels is they are almost never serviced for the usual out of service time.

Detroit requires service for "over 30 days" of non use, most mfg have similar requirements.

So a diesel that has 4000 hours in a 20 or 30 year old boat would be prefered to the same boat with 500 hours.

Gas engines will get 2000 hours of fairly hared use on a plaining IO , if maintainred.

They will go far longer when lightly loaded when used on a big plaining boat operated at displacement speeds.

But again Maint. is king , look for logs and oil sample reports .

A high life engine from a knowlegible owner is by far a better deal than a low time unit with marginal maint , gas or diesel..

-- Edited by FF on Tuesday 14th of February 2012 06:20:02 AM

rwidman · Feb 14, 2012

Tony B wrote:
I am still actively trying to sell my sailboat and get a trawler. Hopefully, soon it will sell.

Buying a 2nd hand boat doesn't always afford the luxury of what type of engine you get with it. having said that, here is my question:

Many motor yachts have twin gas engines in the 250 to 350HP range.

Many mid-1980's boats have around 1200 to 1500 hours on them. Assuming they were exposed to an average amount of maintenance, are these engines still considered young or are the ready to die? Everything has an expected life span, so what is it for gas engines?

Thanks in advance.

As expected, the responses are all over the place so here's mine:

Once you start looking at boats, especially trawlers or motoryachts, diesel power is more attractive and practical.* The larger the boat, the more practical.

Diesel engines have several advantages over gasoline engines in this type of use.* They typically produce more torque and power at lower RPMs, they typically run for two, three, four times as many hours before needing major service, and diesel fuel is safer than gasoline, something that counts if you are living, cooking, and sleeping on top of a couple hundred gallons of it.

To directly answer your question, it depends, but I would say typically, gasoline engines with 1200 to 1500 hours on*them are heading for major work pretty soon.* Diesels, on the other hand, are just getting broken in.*

psneeld · Feb 14, 2012

I think it boils down to this....

I've been running boats since the 60's.* All kinds...all shapes and sizes and powerplants.* I had at least a dozen of major and dozens of*minor*issues with big Caterpillar's down to small outboards while underway.

NEVER did the main engine fail.* If gas it was alternators, electronic ignition systems, water in gas...etc..etc.* If diesels it was clogged flters, water damaged cylinders due to bad aftercoolers made by someone other than CAT (3196s)...failed hose clamps on brand new yachts, etc..etc.

The closest thing to a "failed" engine was a turbo that let loose with 10 hours on the engine.* Luckily I caught it right away and no parts entered the engine and a new turbo/inspection had the engine up in a few days.

So the bottom line is do regular maintenance...doing oil changes and filter changes as often as people say they do is really just a waste of time in my book...200 hours on eng oil and LOOK at your fuel...if it's dirty...yeah the filters may need frequent changing till you fix that problem.* If you overheat or suspect something amiss*(or oil anaylysis) suggests a change...sure it's cheap enough....then cut the filter apart and look at what you have (how many do that?)

When I say don't baby an engine...I mean use it...don't NOT use your generator but 4 times a year.... because you are letting*it rot away by not using it...it's not dying from running it.* Use your boat if you can afford the fuel...don't sit at the dock thinking you'll get another season of engine use 20 years from now.

But getting scared at pure hrs is rediculous...I've had friends shy away from gas engines with 1000 hours*in a relatively new boat and get all ecited in a good way on 200 hr engines in a 30 years old boat...that's insane in my eyes.

As most experienced operators on here have said...it's all about maintenance and how they have been run.* Serious engine failures in my book are from manufacturing defects or REALLY high time engines or from operator error.* So when buying used...you are just rolling the dice unless you have been there for all those hrs those engines have run.* Books/logs can be doctored and too many sellers aren't quite as honest when selling as they should be.

-- Edited by psneeld on Tuesday 14th of February 2012 06:54:40 AM

-- Edited by psneeld on Tuesday 14th of February 2012 06:57:17 AM

-- Edited by psneeld on Tuesday 14th of February 2012 06:58:02 AM

-- Edited by psneeld on Tuesday 14th of February 2012 06:58:42 AM

koliver · Feb 15, 2012

Tony:

I agree with Marin, FF and Scott.
That said, IMHO, the easiest way to ruin a diesel engine is to run it at the dock for an hour once a week, during the off season, as so many do. Simply put, Diesel engines do not like cold starts, nor do they like cold starts after previous cold starts. If you are looking at a boat built in the early 80s or even the late 70s, look for one that has at least 3000 hours. Any less and you know the engine has been left sitting most of the time and chances are the various owners were starting it but not getting it warmed up properly on a regular basis. One rule of thumb that seems credible is that an average boater will only put 100 to 150 hrs per yr on the engines. In a trawler, that no. should be increased a little over planing boats, as we only get 8 knots from our boats, so it takes longer to get somewhere. that 150 hrs, for 30 yrs, is 4500 total for a normally used boat. Mine has over 6000, and I know all the previous owners and their usage patterns. That is not excessive useage. My present engines have 3000 and I still call them "new". My transmissions have 6000, my damper plates haven't been replaced, as they don't need to be. Some say a damper plate only lasts 1500 hrs. I can tell you that with care, they last a lot longer. Likewise the engines. My mechanic suggested light usage, so long as the engines got properly warmed up, will see those engines outlast me.
I sold my "old" engines at 4500 hrs, to a commercial fisher, for a good price, as they were still considered young enough.

I haven't mentioned gas engines, because I wouldn't consider a boat that weighs so little that it would be gas powered. That wouldn't be my idea of a good cruising boat.

Marin · Feb 15, 2012

koliver wrote:
...I wouldn't consider a boat that weighs so little that it would be gas powered. That wouldn't be my idea of a good cruising boat.

*A lot of Tollycraft boats, some of them pretty big and heavy, were gas powered.* While some have been converted to diesel, many of them still have their original gas engines.* I have no idea how their engine longevity stacks up, but gas engines were the norm for many years in larger cruisers like these*rather than the exception that they are today.

Larry M · Feb 16, 2012

We have 7,327 hours on our Ford Lehman SP135.* We should get 12-15,000 hours before major service is required.

FF · Feb 16, 2012

"gas engines were the norm for many years in larger cruisers like these rather than the exception that they are today".

Perhaps in the "good old days" owners were more knowledgable about the use and operation , advantages and disadvantages of gas vs diesel?

Instead of parroting blither about service life (meaningless even with 30-40 years of projected ownership) or old wives tales of exploding boats at every marina.

Some folks understand that a gas engine costs less to replace than 6 injectors in some diesels , and the cost of proper maint and PM is far higher in diesels.

THe "fuel cost saving" on a 200 hour a year yacht engine is meaningless

rwidman · Feb 16, 2012

koliver wrote:
IMHO, the easiest way to ruin a diesel engine is to run it at the dock for an hour once a week, during the off season, as so many do. Simply put, Diesel engines do not like cold starts, nor do they like cold starts after previous cold starts. ...........

That's what I thought but we had a very good diesel mechanic who worked on boats at my marina and elsewhere (so good that he was offered a tour in Afganistan and has been gone for a couple years) and when I asked him about this very question, his response was that you wouldn't want the same exhaust valves open and the same cylinders exposed to air and humidity all winter.

This leaves me thinking you are both right, but it also leaves me at a loss of what to do when the boat won't be operated for a couple months or more.* Pretty much I have been starting it and running it for a couple tenths of an hour every month or six weeks.* The problem is, even if I put it in gear and raise the speed to where I fear pulling the cleats out of the dock or boat, the operating temperature never gets to normal.

*

rwidman · Feb 16, 2012

FF wrote:
............*and the cost of proper maint and PM is far higher in diesels.

I see that statement posted time after time on boating forums, but my personal experience is that the diesel takes two to three times as much oil and coolant and that's the primary difference.* The filters might cost a dollar or two more, but then, there are no spark plugs, cables, distributor caps, etc. to replace.

I understand that replacement of major parts or major service is going to be more expensive, just like the cost of the engine in the first place.

This is my first diesel boat, but I don't think I would go back to gasoline power on a trawler.

*

RCook · Feb 16, 2012

From our experience (Volvo KAD44P-EDC with 4636 hours so far) I'd tend to agree with rwidman.* Ongoing regular maintenance has not been a major cost issue.* Oil/filter changes are more expensive, but that's about it.

Our stern drive, OTOH.......

sunchaser · Feb 16, 2012

A gas engine in a boat is seldom run at the equivalent of 45 mph, more like 80 to 100 mph if you are in a Searay. 8 gph on a gas 350 CID is about 90 MPH in a pickup.

A friend with 454 Crusaders in a 48 Tolly got to 3000 hours and*18 years with perfect maintenence and mostly 6 gph or 1500 RPM.

To me, 700 to 1000* (10 to 15 years) hour on a used and unknown gasser is too big a risk. Been there, done that.

ARoss · Feb 16, 2012

My '73 Lehman has 4600 hours on it if you believe the hour meter. I had the injector pump rebuilt 5 yr ago when I bought the boat, and just posting this is probably a jinx, but the engine performs flawlessly. Annual oil changes usually 100-150 hours) and 50 hr change on the injector pump. No smoke, doesn't run hot. My fingers are crossed.

JD · Feb 16, 2012

ARoss wrote:
My '73 Lehman has 4600 hours on it if you believe the hour meter. I had the injector pump rebuilt 5 yr ago when I bought the boat, and just posting this is probably a jinx, but the engine performs flawlessly. Annual oil changes usually 100-150 hours) and 50 hr change on the injector pump. No smoke, doesn't run hot. My fingers are crossed.

I have a friend that lives in FL and has a GB 36.* He is a retired service manager from a large BMW dealership.* He told me a couple of years back that when he was looking at boats and heard that these engines would run for over 10k hours he just laughed and was sure it was hog wash.

He is now in the 4,500 range on his Lehman and says that 10-15k hours are well with in range if he would have the boat that long.* He would not have believed it without owning one him self.*

psneeld · Feb 16, 2012

Willy wrote:
Issues with inboard power for me have always been associated with the marinized part of the product.

The base engines when treated OK can go for a long long time.

Raw water pumps, water cooled manifolds, oil coolers, risers, heat exchanger issues can and will destroy a solid power plant fast.

But thats been my experience. You know from the school of hard knocks.

Old gas or diesel power plants can be cheap to rebuild and end up very reliable.

The marinized part not so much.

*yep

Marin · Feb 16, 2012

JD wrote:

He is now in the 4,500 range on his Lehman and says that 10-15k hours are well with in range if he would have the boat that long.* He would not have believed it without owning one him self.*

While the question that started this thread is about the life of gas engines, not diesels, I will add this little factoid to the diesel life discussion.* I dont't like the FL 120 for a number of reasons but longevity is not one of them.* A number of years ago I was having a phone conversation with Bob Smith of Ameican Diesel about the stock raw water pumps on our two FL120 and the best thing to replace them with.* In the course of the converstation we got around to the longevity of the FL120.* He told me that in recreational service, assuming regular use, proper operation, and proper service and maintenance, the engine should be good for 12,000 to 14,000 hours before needing a core overhaul.

He also told me that this engine was used in some of the Washington State Ferries way back when.* Not for propulsion, of course, but running pumps or generators, I don't remember which he said.* And these engines went some 25,000 hours before needing a core overhaul.* Of course, they were in near-contnuous service at a constant, conservative rpm.* And they received very frequent monitoring, servicing, and prompt mainenance when it was required.

More recently, I have a friend in Hawaii who owns, among other things, a small fleet of longline tuna boats.* These are mostly about 70 feet long and they go out for a month or so at a time, come home, unload, restock, and go right back out again.* They have one engine, a Volvo turbocharged intercooled dlesel which alslo provides hydraulic power for the longline gear, and a Northern Lights generator that powers the boats' refrigeration systems.* The propulsion engine is run the entire time the boat is at sea.* Maximum rpm used is 1,500 he said.* He has had these boats in operation for many years, and he said that he gets really pissed off if an engine goes less than 30,000 hours between overhauls.

-- Edited by Marin on Thursday 16th of February 2012 02:09:25 PM

Singleprop · Mar 3, 2012

here is an excellent article about duty ratings :

http://sbmar.com/main/articles/continuous_duty_-_a_different_perspective/

RickB · Mar 4, 2012

It is hard to believe Tony has problems understanding the concept of maximum continuous power. It has been the reality of aircraft engines and large marine engines for generations.

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