Contaminated diesel

Have a 45 trawler that has been sitting on the hard for 10 months in the Florida Keys. Awaiting repairs, almost done. Looking for advice on the state of affairs with the diesel that has been on board all that time. 4 fuel tanks, inter connected about 1/2 full, about 250 gallons. Concerned about algae or other contaminants growing and eventually causing fuel problems. I have asked the boatyard to test the fuel and treat for algae if necessary. Any experiences or suggestions for me out there? Many thanks.

Advice that is too late: Fill your tanks up if you are expecting to be on the hard for a long time and give the diesel a treatment in advance.


When you have algae there are enough additives that could solve the problem if any. In the worst case you can pump all the diesel out, clean the tanks, filters and lines and pump the not contaminated diesel back. Algae only are multiplying in the aerea between diesel and water, which is at the bottom of the tanks. The rest of the diesel should be clean.

Why not call a fuel polishing company to clean it in place?

Why do you think it is contaminated??
Ten months in FL is no big deal.
Dont add fuel iust use it as is and change filters if necessary. Unless something else got in the tanks the fuel should be fine.

Unless you have a bunch of water in you tank, you should have no issues, if you had none before.

Greetings,
Mr. ML. Algae does NOT grow in fuel tanks. Algae needs sunlight to grow so unless your tanks allow light in and are actually in sunlight, you have another "bug". As sort of mentioned, the "bugs" live in any water that may be in the bottom of your tank(s) and feed off the diesel at the water/fuel interface.

Personally, unless you've had a water contamination issue in the past, I would simply add biocide and buy a few extra filters and keep a close eye on them (filters) for the first little while. IF the yard finds water during their tests, THEN consider polishing. 10 months is too short a time for any actual fuel degradation IMO. Diesel is not at all like gasoline that degrades in a comparatively short period of time. $.02...

Edit: Aw snap! 7 minutes too slow...

I would not be worried about a 10 month stay unless there was a known reason to think that the diesel is contaminated, like water in the fuel. Just buy some extra fuel filters and know how to bleed the engine.

While it wasn't in Florida, I had fuel sit in my tanks 20 months while going through a major refit project. Used as much of it as I could before refilling the tanks. No problems.

As others have mentioned, have spare filters and keep an eye on the separator bowl for water and gunk.

Ted

I had 100 gallons on board when I purchased, the engine only had 46 hours on it and it was a 14 year old vessel so I pumped it dry and started fresh. The first tank pushed some jello into the filter bowl and it has been clean ever since. 250 gallons is a big difference in quantity though, and expense... I would look into fuel polishing were it me.

If you have a dual filter setup, just use the fuel, have extra filters handy, and keep an eye on them. A vacuum gauge would be a better use of money spent than fuel policy polishing IMO.

Hobo sits in Florida during hurricane season 4-6 months a year (last 4 years anyway). I leave the tanks 1/4 to 1/2 full and have never had any problems. We top off before the next cruise. The racors have never had any water in them.

Woodland Hills said:

Why not call a fuel polishing company to clean it in place?

Click to expand...

Sure polish it and inspect and clean the tanks. I suspect it will be easier to polish on the hard too. At least easier for the guy who has to drag all the equipment and bladders to your boat.

Old Fuel

I don't really see 10 months being a problem. When was the fuel originally put in? If it was in the tank less than a year total I wouldn't worry about it. Top it off with fresh fuel, put some conditioner in it, have some filters handy if you need them and use it up. I would consider topping off after each trip. Hopefully your primary filters separate water - check the bowl several times a day and drain the water as necessary. We purchased our boat a number of years ago in San Diego and took it back to San Francisco. It had been sitting for well over two years and had close to 1100 gallons on board. Replaced 3 Racor 900 filter elements on each engine the first 3 days out then went the next 3 days without a problem. Alternated the tanks and topped off when we could. I was using 2 micron filters so I wouldn't have to change the secondary's at sea and in fact never had a problem with the secondary's. On
the other had 250 gallons is not a lot to either polish or dispose of. We did a lot of coastal cruising all the way down to southern Mexico and up into the Sea of Cortes. We have 4 tanks aboard and even doing long range cruising it's hard to use up 1100 gallons. We made the smallest tank into a day tank and would transfer fuel through a set of Racor 900's each day or two unto that aft tank.

We used to have specialty type drilling rigs that we would only use occasionally for special jobs. Sometimes they would sit out behind the shop for a couple of years until the type of work would come up that those machines would be handy for. We would throw a battery in them, fire them up and roll them into the shop and change the oil, grease them, and go to work. Never any fuel problems. I've worked with heavy equipment my whole life, after a while I learned not to worry about problems I might have, I usually had some I did have, to keep me awake at night. I'll bet you will be fine unless there was water in there before you put it up. If so, there's a bunch of good advice above.

My current boat sat 6 years before I came along. No mothballing of any kind. I used algae-x at a 3x dose. Idled the mains, ran 2 generators, no problems. Added some new fuel and did a 20 mile test run before a 600 mile home run. No problems. Changed fuel filters before the home trip.
I've found what I think is a better product, Archoil 6200. Read about it here if interested: Archoil | The Latest Developments In Nano lubrication
Made a huge difference in my Ford diesel pickup, a kind of common rail. Thought I needed injectors, but made them run like new. It gives me 6-10% better mileage. Boat also gets better mileage. I hold 2000 gallons and have zero fuel problems.

That is interesting, but it would have to provide a LOT of benefits to be worth the $45 it takes to treat my full fuel load.

Just a note to update. Testing confirmed heavy contamination both water and algae. Going the polishing route plus treatment. Thanks for all the advice.

See post #6 re algae. Might want to confirm with the yard - may be some other bugs, but not algae.

Out of curiosity, how much would it cost to have someone come to your boat and polish 250 gals?

10 months is nothing especially if you were going through your fuel regularly before it was hauled out. if it were 3+ years then i would have the tanks checked.

If you have any concern Power service makes a good additive and also has a aleage additive. Used it in all of my diesels before and after this low sulfer fuel came around. Extreme cold weather 0 F in NJ when dosed correct never had a fuel issue. Only issue is dirty fuel clogging up our dispenser filters in less then a month. This started when a new management company took over at the fuel station.

Diesel is more stable in the long run then gasoline has ever been. Should have no issues just believe in your filter system and have spares.