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Aging Diesel Fuel

shank

.
Apr 20, 2016
83
Catalina 27 Lake Champlain
Hello, I bought a Catalina 27 last year which has a Universal 5411 diesel inboard. The previous owner was nice enough to fill the tank for me. As you probably know, this engine is like the Prius of diesels and barely uses any fuel and at the end of this second summer of sailing, I'll probably still have 3/4 of a tank left. I'm in Vermont and we haul out our boats every year and last winter I treated it with diesel fuel treatment. I'm not having any problems at all with the fuel or engine but when does diesel become too old to use any longer? Can I just keep treating it every winter or should have the old fuel pumped out and refilled at some point?

Thanks
 
Jan 7, 2011
2,836
Oday 322 East Chicago, IN
I am a bit farther south, but still have to haul out every October…

I let my fuel tank run down in the sailing season, and top it off again in the fall at haulout. I put some fuel treatment in when fill the tank (not too full…don’t want it to overflow on a warm day).

No problems with my “Prius” thus far!

Are you on Lake Champlain? My brother in law is In Essex Junction.

Greg
 
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shank

.
Apr 20, 2016
83
Catalina 27 Lake Champlain
Hello,

Yes, on Champlain. It has been a great lake for sailing.

Sounds like you haven't had any problems with old diesel so that's good news.

Thanks for the response.
 
Jan 11, 2014
7,748
Sabre 362 113 Fair Haven, NY
Unlike gasoline, diesel does not degrade much over time. It is susceptible to water intrusion from condensation and other sources. It is a good idea to top off the tank in the fall before haul out and use BioBar JF as an additive. BioBar JF is a biocide that prevents the bacteria in the fuel from growing and forming the sludge that clogs filters.

There are other additives that can be used to treat the fuel, I use Startron along with BioBar with each fill up. Check Pratical Sailor, they have done some research on diesel additives. The author of those articles is a chemical engineer with experience in the petroleum industry.
 

DougM

.
Jul 24, 2005
2,169
Beneteau 323 Manistee, MI
I too am up North in Michigan and haul out annually for winter storage. I have been averaging 5 gallons of diesel use each year. I store with a full tank and add stabilizer. Twice I have had to leave the boat over two winters without launching between. I have to believe that the ratio of stabilizer to fuel is higher than recommended.
I have not had fuel problems, and even after two winters, the engine has started with no problem and runs well. I have only drained the tank one time and when I did, the fuel was still transparent and pink.
 
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shank

.
Apr 20, 2016
83
Catalina 27 Lake Champlain
Thanks everyone. I guess I'm just more used to gasoline and how it deteriorates and gums up an engine. Sounds like that's not the case with diesel. At this rate, my kids will inherit a boat with a full tank of fuel.
 
Jan 11, 2014
7,748
Sabre 362 113 Fair Haven, NY
Since you are new to diesels, a couple of quick tips.

Diesels like to be run, not idled. Idling builds up carbon deposits in the exhaust elbow among other places.

Run diesels at about 80% of wide open throttle. Find the max RPMs and then take 80% of that as the optimal cruising RPM. Once in a while run it at WOT.

Water in the fuel is a big issue.

Follow the recommended oil change interval or change every fall.
 
Feb 21, 2013
3,638
Hunter 46 Point Richmond, CA
Excellent advise above. I will add that I stored a skiboat with a full tank of gasoline containing a stabilizer and oil-fogged engine and a Hunter 386 sailboat with less than a tank of diesel for 3 years while overseas. Both started up after my return (after replacing their batteries) without an issue.
 
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Mar 26, 2011
2,918
Corsair F-24 MK I Deale, MD
Normally I would say run the motor more. But lake sailing that won't happen. The conventional wisdom is to store the tank full, but not so much if it is going to be years.

I would use Biobor JF and add a silica jell vent drier. This will keep moisture out AND reduce breathing (oxygen). That is waht we do in industry for water sensitive chemicals. I have also had excelent results in multiple lab (which is outdoors in this case) and field tests. I would then keep the tank relatively low to reduce the age of the fuel in the future.

And run the motor more! Not just idle or a little more to clear the jetty. Full cruising throttle for some hours. The motor will thank you.
 
Jan 1, 2006
5,995
Slickcraft 26 Greenport, NY
The Mack Boring guy, Larry (I can't remember his last name), suggested to our class to do a "Motor Weekend" now and then. His point was that our typical run past the jetty to get the sails up doesn't even warm up the engine and diesels like to run hot. They need to warm up to boil off the condensed water in the oil, to reduce friction on the engine components, and put some amps in the battery. It was also his opinion that running the motor on the mooring doesn't do it.
Don't forget about fuel polishing services.
 
May 24, 2004
6,769
CC 30 South Florida
Fuel becomes too old when it won't fire the engine. Don't think the diesel fuel you pumped in this morning is new, it has probably been sitting for months in storage or transportation tanks. By the time this fuel reaches your boat it has its share of microorganisms growing in it. The rate of growth of microorganism I don't think varies significantly between old and new fuel. We treat our fuel at every filling. Over time many micro organisms will die and their remains settle at the bottom of the tank creating a gelatinous gunk. This is the stuff that will clog filters and even cut fuel flow. Would recommend you replace your primary and secondary fuel filters on a yearly basis and always carry spares. If after a brisk sail you feel you are loosing engine power that would be an indication that the sediments at the bottom of the tank have been stirred and are starting to clog your filters. When filter clogging starts to be too frequent it is likely time to polish the fuel and clean the tank. Water is another consideration, when storing fuel in a partially filled tank repeated cycles of condensation will increase the amount of water in the fuel. Just make sure you drain your fuel separator periodically. Some people keep a full tank and others like to keep very little between seasons. I'm not sure if one method is better than the other. To answer your question, the age of the fuel is not what causes problems but how practically clean can it be kept.
 
Jan 1, 2006
5,995
Slickcraft 26 Greenport, NY
In Feb which grew into March we brought a powerboat down from the Chesapeake to Florida. The boat had sat for "Some time" but we know it was at least 2 years (From the listing). It had the Volvo pod system with twin engines and sensors for absolutely everything - things I didn't know you could sense - and they could all send the boat into the safe mode. We had nothing but trouble. Calm day flat water we could cruise. Rougher weather out in the Ocean the engine system would go into the safe mode probably due to filter clogging. We replaced filters again and again. And finally the secondaries. Still had problems.
I can't help but think if the seller, or the broker, had bothered to have the fuel polished, even at the buyers expense we would have had a much faster trip. Everyone knew the boat was going to FL but no one did anything (Including the captain I was working for). It didn't matter to me 'cause it was an expense paid trip. But it should have been a 6 day trip that took 15 days because for much of it we couldn't go planing speed. If you think fuel polishing is expensive, ponder the costs of dockage or storage, mechanical work, meals and bar bills in destination away from home. Being on vacation is fun. Being stuck somewhere with the meter running isn't.
 
May 24, 2004
6,769
CC 30 South Florida
Rougher weather out in the Ocean the engine system would go into the safe mode probably due to filter clogging. We replaced filters again and again. And finally the secondaries. Still had problems.
Had a similar situation once in a friends sailboat. He had two Racor spare filters, used them both and both got clogged. Decided to leave the Racor without a filter element and placed my hopes on the secondary for which he had one spare. The engine ran flawlessly until we got to our destination. Quickly replaced the secondary filter and to my surprise it was not as dirty as I had anticipated. I checked the microns on the Racor filters and they were 10m. suggested to my friend he buy 30m from then on.
 

Blitz

.
Jul 10, 2007
609
Seidelmann 34 Atlantic Highlands, NJ
I've always used the Rancor R24S filters, which are 2 micron and replace them every other year. unless I do some serious cruising I probably use less than 10 gallons of Diesel a year.

I have used the BioBor JF for the winter, seems to be pretty good. Also use the BioBor MD as I add any fuel during the season. This has kept everything clean.

also, as other have said I run my engine at 80%, and seems to keep it clean.
 
Mar 26, 2011
2,918
Corsair F-24 MK I Deale, MD
I've run both standard and modified (marine) accelerated aging tests with gasoline and diesel, and diesel is at least 20 times more stable regarding oxidation and polymerization. A few years is nothing special, if you can keep it clean and dry.