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Old 10-05-2015, 14:20   #31
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Re: Diesel engine life expectancy

I had my fuel/tanks polished two years ago. The five tanks hold 1500 gallons, and I had about 750 gallons of fuel. The bill ran around $1800. Yes, the tanks were full of crap (gray, sludgy, bacteria). Even after polishing, I went through fuel filters at a pretty rate for another year. Most of the diesel I buy has biocides already added. Condensation aggravates the problem, so I try to keep my tanks full during the off-season.

I mentioned 220hp continuous to indicate the size of the engine. It's rated continuous at 2200rpm Peak 235 @2600, and I run at 1500, troll at 600. Yes, we do horrible things to engines, but that's the nature of the job. My engine life expectations are based the use other trollers get out of their engines and the hours on my last engine (6-71) had when I gave up on it. I put somewhere around 1500 hours/year on the engine.

And yes, the photo show the parallel filter arrangement I use.


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Old 10-05-2015, 14:20   #32
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Re: Diesel engine life expectancy

We have both dual Racors (throw a lever to switch) and a fuel polishing system, with 20 and 10 microns in series, about the same size filter as the big box whole-house water filters.

The longer it polishes, the finer particle it takes to make it through the filter, so by the time I have to swap filters, it's way finer than 10 microns. My first Racor change was at over 1000 hours, and turned out to not be the problem (loose fitting = air got in). Just on general principle of using both of them, I switched today, at about 400 hours. Sometime when we're not rocking and rolling so much, I'll pull the 400 hour filter out and, maybe, clean out the housing.

Our fuel polishing system is how I think I got to that point...

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Old 10-05-2015, 17:30   #33
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Re: Diesel engine life expectancy

In many regards it boils down to weight vs horse power. Many boats in the west coast fishing fleets have old Bedfords, 71 series GMCs/Gray Marines or Buddha diesels that have worn out their previous boats, I.e. These engines have outlasted the original boats they were installed in and many with tens of thousands of hours.

As diesels get lighter and more HP is squeezed out of them, their life expectancy diminishes.
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Old 10-05-2015, 17:40   #34
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Re: Diesel engine life expectancy

I have the twin 14hp yanmar on my APU (auxillary power unit) on my semi truck, 22,000 hrs and running strong, serviced every 600 hours, my guy says hes seen them over 30,000 hours.
Filling the tanks to minimize condensarion will save injectors.
Add some algeacide to counteract the effect of biodiesel labeled (B5 to B20). Allow a good warmup to prevent fuel from getting in your crankcase oil and causing dilution.
Avoid short runs, always run at high (100 to 150 rpm above low idle) idle to bring up oil pressure, a full throttle run after warmup will blow out carbon but cruising at 55 -70% will get the best fuel mileage and engine life.
Lots of good tips from other posters too.
Normal for the crankcase oil to look black even after a change, unlike gas engines that look cleaner.
I have converted old mercedes cars and power stroke ford pickups to run on WVO (old french fry oil) but thats another story.
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Old 10-05-2015, 18:32   #35
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Re: Diesel engine life expectancy

Originally Posted by valhalla360 View Post
Most marine engines die from abuse and neglect not hours.

I believe the normal assumption is around 100hrs motoring per year, so 2000hrs is 20yrs, likely the 2nd or 3rd owner and odds are the abuse and neglect has started.

If they are running well, count yourself lucky, keep up on the maintenance and you should get many more hours out of them.
Yup - if they are well maintained, average life expectancy = lot longer than mine.
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Old 10-05-2015, 22:42   #36
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Re: Diesel engine life expectancy

It's funny about diesels. When I talk to a friend with a big farm and tell him I change the oil in our Yanmar every season (100 or so hours) he thinks it's funny, since he also changes the oil in his tractors and harvesters once per season but might get 1,500 hours per season. As long as a diesel gets clean oil, clean fuel and clean air, they will last virtually forever. The hardest thing on a sailboat engine is sitting idle over the winter and collecting moisture in the crankcase. If you are a cruiser and run year round, keep the oil and fuel clean, if it is not burning oil or using excessive fuel the engine is not close to being near the end of it's useful life.
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Old 11-05-2015, 07:11   #37
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Re: Diesel engine life expectancy

It doesn't cost a lot to have an oil analysis done. I think Blackstone labs runs about $25. Well worth it to know what condition the engine is in. But it all boils down to how has it been maintained and abused. The analysis is very hepfull in that. I don't change the oil every 50 hrs. I would be changing it several times a year in that case. Mostly due to sailing in sw Fl. where there will be several days of no breeze to sail with. Then the iron jenny has to pull the load. Or sit in the sun and bake. So Just like with the rest of my vehicles, I change by miles. Usually with the Perkins about 500 or so..
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Old 11-05-2015, 07:44   #38
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Re: Diesel engine life expectancy

Originally Posted by Siberian Sea View Post
Look at the engine anti-freeze and if your using the green stuff you might want to think about flushing the system and converting to the red colored longer life coolant. NEVER mix the colors. Anti-freeze has chemical compounds that fight against electro corrosion inside your engine and this stops nasty things like cylinder sleeves from being eaten away as well as oil and trans coolers. The red colored coolant last much longer.
It is correct that one should NOT mix engine coolants that use different chemistry. One also should use coolant rated for diesel engines.

However, one cannot tell the coolant chemistry based on color. You have to read the label to verify chemistry and if the coolant is rated for diesels.

The diesel engine in my Ford pickup truck was made by International, and when new, used a gold colored coolant. My JD tractor has a Yanmar engine with a green colored coolant. That coolant is NOT the green colored Prestone gas coolant but a diesel rated coolant using the same chemistry as the Ford gold colored coolant.

When the coolant needed changing in the International and Yanmar, I bought quite a few jugs of JD green coolant to use in both engines. The chemistry was the same as the Ford coolant, cheaper, and I could get the coolant from from the same store.

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Old 11-05-2015, 08:14   #39
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Re: Diesel engine life expectancy

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Old 11-05-2015, 09:09   #40
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Re: Diesel engine life expectancy

A well taken care of diesel engine should see 15,000 hours or better. My Volvo MD21a sat for 15 years without running. The fuel was removed, polished and she runs great hitting hull speed at 1800 rpm. The base engine is a Peugeot taxi engine capable of 4500 rpm. The engine is 40 years old and has about 900 hours on it.
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Old 11-05-2015, 09:31   #41
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Re: Diesel engine life expectancy

Originally Posted by ozsailer View Post
Hello all,
We bought our Lagoon Catamaran in February last year. At the time both engines had just under 8000 hrs on each of them. When purchasing the boat we budgeted and negotiated on replacing both motors.
Now 18 months on and almost 700 hours added to each motor they are still going very very strong. They are not using any oil or water. We just had a service which identified some minor issues with bolts vibrating out of an engine mount and a suspect water pump but on the whole no big deal.
Now the question arises how much life can I expect out of these motors. (Both Yanmar 40 HP sail drives) Researching the web has not really identified expected life spans. In fact I have found many boats that are in excess of 50 years old with the original motor still working. I have also noted the perceptions of a lot of boaters I speak with that in general they consider 2000 hrs to be a lot of use on a boat. So what do we as a boating fraternity base our opinion on, fact or perceptions. I must admit I always was of the opinion that 2000 plus hours was a lot of hours on a marine motor but now I am thinking otherwise.
I would be most interested to hear members thoughts on engine life and also the hours people have on their motors. I take it as a given that good life also equates to good maintenance and service.
Looking forward to your responses

Greg and Sue
SV Sunshine
The factors that reduce a diesels life expectancy are:
1) short runs that dont allow the engine to get to operating temperature
2) dirty fuel
3) overheating
4) runaway where they overrev after ingesting gas or fuel vapor
5) dirty oil
6) lack of oil

If a diesel has not experienced any of the above then you should expect to maximise its useful life.

Diesels are notoriously hard to predict life expectancy. 1.5 million miles (not hours) for long haul trucks is not uncommon. 10,000+ hours for a recreational yacht auxilliary engine is rare.

Our Perkins 4-236 was owned and operated by a pedantic aircraft mechanic for 21 years before we bought the boat. He equipped it with a preluber which circulates the oil before starting. This is a cheap and effective way to increase the life of any engine and also useful for oil changes.

We are at 3800 hours and have clean oil. Unheard of in most diesels and a good indication of good ring sealing. Compressions are good, oil consumption is only a quart per 50 hours, which is a good indicator that oil control rings are in good condition.

I'd expect 10,000 to 15,000 hours from this engine. We change oil and filter every 50 hours. I also get each oil change sampled. This will tell you much about what is going on inside your engine. I was a motorsport mechanic for 2 decades so I know my way around engines better than most.

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Old 12-05-2015, 10:57   #42
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Re: Diesel engine life expectancy

Diesel engines like to be run every day for long periods each time and a constant RPM. That's why over-the-road truckers get hundreds of thousands of mile out of a properly served diesel engine. Active power boats, same story. Sail boats, especially lightly used one like mine, are the real problem with diesel longevity. Ten minute warm ups, ten minutes out of the slip with the process reversed when returning to the marina, all a low RPM, are the real killers of diesel engines. Low RPM operations should be augmented by at least 20 minutes of steady running at 2000 RPM or higher to prevent cylinder wall polishing. Diesel used to be cheap but no more. Too bad they don't invent an engine for small auxiliary sail boats that burns non-flammable gasoline, which they would also have to invent.
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Old 12-05-2015, 18:14   #43
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Re: Diesel engine life expectancy

As you know, our Yanmars are also just short of 8,000 hours old & still going strong. We have rebuilt both raw water pumps, had 1 starter motor serviced, replaced an alternator, replaced 1 engine mount, replaced belts - all to be expected given the age & useage.

We change oil & filters every 100 hours, check all fluid levels, belts etc regularly, adjust valves as per spec. The motors don't blow any smoke & still make full specified revs under load.

Living in a rural area, my diesel mechanic/workshop does mostly farm machinery including many Yanmar motors. His advice is that they should give us many many more hours yet. He said just maintain them properly & use them, then if/when anything major does go wrong he would re-build them.


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