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Old 26-12-2019, 05:00   #31
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Re: Yanmar Engine Life Expectancy?

The OP has probably dealt with the glazing by now - it was 6 years ago when he asked the question

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Old 26-12-2019, 05:19   #32
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Re: Yanmar Engine Life Expectancy?

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The OP has probably dealt with the glazing by now - it was 6 years ago when he asked the question

Well, that takes care of that!
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Old 26-12-2019, 08:39   #33
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Re: Yanmar Engine Life Expectancy?

I agree the OP is long long, but for others that may be reading this post. The issue as I see it with OP's situation is a grossly over powered boat.

His boat, a Bluewater 420CC has a light displacement of roughly 11,000 kgs and a LWL of 10.67 m. By my calculations that boat needs 50-51 shaft HP to drive her to 7.9 kts, her theoretical hull speed. He has a 75hp engine, so how will he ever load that engine to the recommended 70-80% unless he's trying to climb the bow wave?

Do not confuse rpm with loading. The relationship of propeller shaft hp to loading is not linear so the typical maths using rpm is a false reading. If it was a linear relationship how many gensets running at 1500 or 1800 rpm would last past 1000 hrs?

If you are overpowered, as in this case, the long term solution is to overprop, giving up some top hp, install a exhaust gas pyrometer and run the engine in the manufacture's recommended temp range.
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Old 26-12-2019, 09:59   #34
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Re: Yanmar Engine Life Expectancy?

The whole if you want a Diesel to last, run the snot out of it is such a persuasive old wives tale it’s hard to make it go away.
Running the snot out of any motor will decrease it’s life, including a Diesel.
First it’s pretty well established fact that Commercial rated Diesels last longer than pleasure rated ones but why? The reason is that a Commercial rated motor is de-rated, same motor for pleasure is rated at 100 HP at a higher RPM, where for Commercial use, it’s rated at a lower RPM and power output, quit a bit lower maybe 75 HP.
Why? Because if you don’t run the snot out of it, it will last longer, and the manufacturer needs the reputation of a long lasting motor to sell in the Commercial world, so they set the Governor to where you can’t run the snot out of it, and this is likely where the myth of running one hard makes it last, because on a Commercial motor 75% max RPM is about 50% RPM on the same motor rated for pleasure use.

Secondly it’s also pretty well established that the longest lived Diesel motors are very often generators. Why do you think that is? It’s because they are most often run at 1500 or 1800 RPM. They are still the same motor that’s rated at 3600 RPM in a pleasure boat, but run at much lower RPM so the Hz rate of the generator is correct.

There are many 3600 RPM generators out there, and every single one of them has a reputation of not lasting long, why is that?

If you want your pleasure rated motor to last a very long time, change it’s oil often, load it properly and run it at usually about half of max RPM for cruise, not 80%
And blowing it out once or twice a day doesn’t hurt either.

Many well made Diesel engines will tolerate being run hard, better than most gas motors, but it doesn’t not make them last longer.
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Old 26-12-2019, 10:49   #35
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Re: Yanmar engine life expectancy?

Quote:
Originally Posted by kev_rm View Post
You heard it here first, folks - Hone your engine without taking out the pistons.

LOL
LOLOL, YOUD BETTER RE-read that post.
It says no such thing.
In fact mentions pulling the head and Pistons.

Once rings are not rotating in the piston ring lands, is when glazing will occur.
Low RPMs can cause ring lands to clog.
You'll not clean dirty ring lands with WOT operation, you may in fact break one or crack one.
Be sure you load the engine with high rpm operation.
not just WOT AT THE DOCK.
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Old 26-12-2019, 13:21   #36
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Re: Yanmar Engine Life Expectancy?

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Originally Posted by a64pilot View Post
The whole if you want a Diesel to last, run the snot out of it is such a persuasive old wives tale itís hard to make it go away.
Running the snot out of any motor will decrease itís life, including a Diesel.
First itís pretty well established fact that Commercial rated Diesels last longer than pleasure rated ones but why? The reason is that a Commercial rated motor is de-rated, same motor for pleasure is rated at 100 HP at a higher RPM, where for Commercial use, itís rated at a lower RPM and power output, quit a bit lower maybe 75 HP.
Why? Because if you donít run the snot out of it, it will last longer, and the manufacturer needs the reputation of a long lasting motor to sell in the Commercial world, so they set the Governor to where you canít run the snot out of it, and this is likely where the myth of running one hard makes it last, because on a Commercial motor 75% max RPM is about 50% RPM on the same motor rated for pleasure use.

Secondly itís also pretty well established that the longest lived Diesel motors are very often generators. Why do you think that is? Itís because they are most often run at 1500 or 1800 RPM. They are still the same motor thatís rated at 3600 RPM in a pleasure boat, but run at much lower RPM so the Hz rate of the generator is correct.

There are many 3600 RPM generators out there, and every single one of them has a reputation of not lasting long, why is that?

If you want your pleasure rated motor to last a very long time, change itís oil often, load it properly and run it at usually about half of max RPM for cruise, not 80%
And blowing it out once or twice a day doesnít hurt either.

Many well made Diesel engines will tolerate being run hard, better than most gas motors, but it doesnít not make them last longer.
Where to start here - much of this needs clarification and correction.

First, commercial and recreational engines are not the same - they comply to specific ISO standards for types of usage. As a matter of fact, there isn't even a "Commercial" or "Recreational" rating, though some engine manufacturers attach those monikers to their interpretation of the ISO ratings. There are ratings that are designed for certain use-cases such as continuous heavy duty, intermittent, etc. The blocks are the same, many of the moving parts are not - valves, cams, pistons, crank, etc.

Second, 1500/1800rpm generators are not 3600rpm engines run at half-speed. They are designed to run at a constant RPM under half-load but with enough headroom on the power curve to accommodate higher loads without bogging down. Again, the internal components of the engine is different than a propulsion version of the same engine.

The ISO standard has variables in load factors and usage that the engine is designed for. Continuous Load engines are designed to be run at 80%-100% of load around the clock. Run them at 65% and you'll have a much, much shorter lifespan. Conversely, there are engines designed to run at 40% load. Run them at the same 65% load and you'll also have a shortened service life. There are engine ratings that run 100% of load but only short duration (think short-distance pilot boat).

The engines in most recreational boats are designed to run between 40%-65% load (load is not the same as RPM - load is best approximated by % of fuel-burn compared to rated fuel burn, in weight - a friend's boat with new Cats has an onboard computer: 65% load is around 85% RPM), and should be propped to allow +/- 85% of rated RPM. But they also contain a standard of ratio of running full-load (most are 1 in 8 hours or so).

Bottom line: the engine in your boat should have been selected as being appropriate to move the boat at hull-speed for up to around 500 hrs/year. Run it a lot lower than that, and you're babying it. It is also designed to take short-duration poundings without harm. Frankly, Yanmar provides less information than other engine manufacturers such as Deere, Cat, and Cummins.

Also, the engine in your generator is designed to run at a constant RPM and provide the foreseeable power your power head is expected to deliver. Run it light or over-size the genny, and you will shorten the lifespan. Northern Lights was originally called ADE - Alaska Diesel and built generators for the oil patch where genny's ran for a year or two between rebuilds.

Finally, to achieve the engine ratings and anticipated usage, the internal components of the engines are indeed different. The valves, overlap, stroke, camshaft, crankshaft, etc. are designed for the ISO rating.

I hope this helps despite the woefully dated thread (I hate it when that happens)
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Old 26-12-2019, 13:43   #37
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Re: Yanmar Engine Life Expectancy?

Your largely correct on the big motors, but not so much on small Diesels like in most sailboats.
For example Nexgen with even their much larger generators simply buys off the shelf Kunota industrial motors, and bolts generators they buy from other manufacturers on them, these same motors without any modifications or additional parts will also be used in forklifts etc.
They aren’t alone in this most small manufacturers do this.

But even OTR trucks don’t run near or even close to max RPM unless they have a big hill to pull. The rest of the time they turn on average about 1400 RPM.

Any engine that’s run at 75% or more of its actual max capable power output or RPM and not a derated number lives a relatively short life.
It is why there are very few if any successful auto to airplane engine conversions.

For example take your car, even a Diesel if you think it matters and select a gear so that it’s running 80% of its redline, set the cruise control and see how long it lasts.
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Old 26-12-2019, 14:08   #38
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Re: Yanmar Engine Life Expectancy?

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Originally Posted by a64pilot View Post
Your largely correct on the big motors, but not so much on small Diesels like in most sailboats.
For example Nexgen with even their much larger generators simply buys off the shelf Kunota industrial motors, and bolts generators they buy from other manufacturers on them, these same motors without any modifications or additional parts will also be used in forklifts etc.
They arenít alone in this most small manufacturers do this.

But even OTR trucks donít run near or even close to max RPM unless they have a big hill to pull. The rest of the time they turn on average about 1400 RPM.

Any engine thatís run at 75% or more of its actual max capable power output or RPM and not a derated number lives a relatively short life.
It is why there are very few if any successful auto to airplane engine conversions.

For example take your car, even a Diesel if you think it matters and select a gear so that itís running 80% of its redline, set the cruise control and see how long it lasts.
OTR truck engines are deigned for a wide duty band and would be designed accordingly running WOT for 20-mina getting up a steep hill is expected . Same engine designed to run some sort of industrial conveyor where load is constant would be designed accordingly and not interchangeable with OTR.

I can't speak to NexGen generators. Northern Lights and Onan work with the engine manufacturers to source a correctly designed and sized engine for the allocation. If NexGen doesn't do that (and they almost certainly do), it's a good reason not to buy a genny from them.

ISO compliance for Yanmar was not easy for me to find so I can't speak to them. The smaller engines for sailboats (versus inboard sport fishers) appear to be designed for less than 40% load factor (guessing around 60% WOT RPMs) with 5% full-load tolerance, meaning you can run-up to full load for 30-mins ever 10-hours or so. These would indeed tolerate low RPM running much better than an older Perkins of Universal. Yanmar is also a popular brand for small sport fishers where a pair of 300 hp would be fitted. Running these light or trolling to excess would be a death sentence whereas the smaller sailboat engine designed for lighter duty would handle relatively well (within reason)

Bottom line - modern Diesels are designed within a duty band that is described in a recognized ISO standard. Run them significantly outside those design parameters - either above or below - will shorten life. With some exceptions, it's harder to do damage by over use than under use. Run your engine. Run it harder than you think. It's built for it.
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Old 26-12-2019, 16:04   #39
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Re: Yanmar Engine Life Expectancy?

It seems our major disagreement is in the designed for each specific duty.
That just isn’t done with smaller motors like in sailboats, yes for larger motors there are some parts differences, but they aren’t usually all that big, a motor meant for higher output will have a deeper pan, maybe an oil cooler and better cooling provisions, but they aren’t going to have major parts differences, those that are, are different motors, yes they share the same block but in the catalog they are different motors.

The little three cylinder Yanmar Diesel I had in my John Deere lawnmower is nearly identical except for marinization to the little 3 cyl marine motor, but Yanmar is smart enough so that the same part will have different part numbers, so your not going to John Deere and buying parts for your sailboat motor.

But I believe your correct in saying they were designed to be run around 60% of max RPM, these are not big Cats, or Cummins, Mann etc. these are little light duty, small in physical size, lightweight high RPM Diesels, high for direct injection anyway, the early VW IDI Diesel would turn above 5,000 RPM, but not for long of course.

For their weight and size, they are actually pretty high HP motors, and that comes at the cost of duty cycle, they can’t be run continuously as hard as big, heavy duty Diesels.
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Old 28-12-2019, 09:00   #40
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Re: Yanmar Engine Life Expectancy?

When you see how long diesel engines last in applications like tractors and big trucks, it's makes you realize that if treated anything but really badly, you should get a lot of hours and years out of one.
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