How clean should a diesel tank be?

[MicHughV]

I think you hit the nail on the head. While most folks take notice of the fill line, the vent line, typically on the side of the hull, escapes notice and it's there that moisture, rain, wave splash, condensation, etc, can find it's way into the tank.
While filters like Racor will trap water in the fuel supply to the engine, it does not address any water inside the tank.

[boatpoker]

When I designed my new tanks two years ago I went with a bottom feed. Any gunk or water immediately goes to the filter and never sits in the bottom of the tank.

[Ded reckoner]

My recommendation is to install your own fuel polishing system. As mentioned, this will help keep a clean tank clean. But, there is great value in running your polishing system when you go out with any kind of pitching or rolling or pounding of your boat, because that is when particles/dirt will come off the bottom or sides and can be filtered out. You won't be able to clean the bottom or sides well sitting at a dock unless you are using a very specialized professional system.

If you encounter rough seas with the tank as pictured, you should be prepared to replace fuel filters, both primary and secondary, en route.

Otherwise, diesel is an ecosystem. We add BioBor, which is a biocide, every other month (or else whenever we refill fuel) to kill whatever is growing in there and then, a day later, do fuel polishing for the calculated length of time (based on the gpm pump rate) for twice the tank volume.

[Uncle Bob]

Originally Posted by boatpoker

When I designed my new tanks two years ago I went with a bottom feed. Any gunk or water immediately goes to the filter and never sits in the bottom of the tank.

As are mine however I took the opportunity to add a sedimenter to each fuel line prior to the primary filter, so far they have caught some asphaltenes and a small amount of water, filters are as clean as.

[mbianka]

When I pulled my diesel and converted to electric propulsion in 2008 I had to empty diesel tank. I found a lot of grime left on the bottom and sides of the tank.
https://biankablog.blogspot.com/2011...-of-grime.html

I was able to easily clean the tank using a small hand held steam cleaner and some paper towels.

https://biankablog.blogspot.com/2011...ing-ahead.html

[Dockhead]

Originally Posted by SailingHarmonie

A diesel tank should be spotless. NO water, NO gunk, NO suspended solids, NO foreign matter. That tank is filthy and your engine would likely stall in rough seas as that crap got mixed to the point it reached the intake line and clogged filters, or worse, injectors.

Seriously, your diesel tank should be cleaner than your potable water tank.

Have that tank professionally polished before you run the motor.

This.


That tank is in very poor condition. You're lucky if you haven't had fuel problems.


Get it professionally cleaned if you are not confident that you can do it yourself. That's diesel bug waiting to happen.


As the previous poster wrote -- the fuel tank should be immaculate, spotless.

[Dockhead]

And by the way, OP should check his tank filler o-rings. That is the most likely source of that contamination.


I've said it before, but I'm going to be a broken record today -- flush deck-level fuel tank fillers are from the devil. If you have one of these, be fanatical about o-ring condition, cap tightness, etc.

[boatpoker]

Originally Posted by Uncle Bob

As are mine however I took the opportunity to add a sedimenter to each fuel line prior to the primary filter, so far they have caught some asphaltenes and a small amount of water, filters are as clean as.

Got a photo of that ?

[Greatest Lakes]

Many of you are making me feel better about my tank.

That said, there should be nothing in your fuel at all other than the red dye, if you are lucky. If you don't mind a bit of work, you can post on Craigslist or Facebook that you have free diesel for anyone with a pump and polisher who wants to drain your tank.

Rubbing alcohol (90%+) can be used to rinse and wash the inside of the tank. It picks up any water, and kills anything alive. You can then get out any remaining solids, and once it looks safe, refill with clean diesel. Change all the fuel filters. You may consider dumping the diesel from the return line from the engine for a gallon or so to be sure the critters are out. As someone else mentioned, check your filler cap and be sure it seals correctly.

Sounds like a lot of work until you compare it to the cost of rebuilding the fuel system of your diesel, and having to do the tank anyway.

[SailingHarmonie]

Originally Posted by boatpoker

When I designed my new tanks two years ago I went with a bottom feed. Any gunk or water immediately goes to the filter and never sits in the bottom of the tank.

That of course has its advantages, but would not pass on a USCG inspected vessel, or on any new boat build.

I wouldn’t do it myself because of the risk of an uncontrolled spill. But it is your boat, and your risk assessment is different than mine. My tank is also set up so I can easily reach down to the deepest point with a hand pump to see what lives there.

[efanost]

Thanks everyone for the wisdom. I shall get that tank squeaky clean as soon as I can! (I'm in the Baltic sea btw, since someone was wondering)

[Dockhead]

Originally Posted by Greatest Lakes

. . Sounds like a lot of work until you compare it to the cost of rebuilding the fuel system of your diesel, and having to do the tank anyway.

This.

[Tom G]

North Coast Joe,
Your mention of a desiccant dryer on the vent line caught my attention. Please provide details. Thanks very much.
Tom G
SV Baloo
HR352

[singlespeed]

Be sure to disconnect the inlet side hose from the fuel filter assembly and force clean diesel through the inlet line. I used a large syringe, purchased at an animal
/farm supply store. Many boats have screens on the tank side of the inlet. A couple of minutes of bouncing in chop and the screen, even two inches above the floor of the tank, will pick up the now suspended "gunk". Vacuum guages are a good indicator, but you need to monitor them every time you fire up the motor and add the reason to your checklist. Far too few commercial fueling operations have a routine tank cleaning schedule, relying on filters in or just prior to the pump to solve any issues. Low volume operations are the worst, especially after they have just been refilled. So called Baja filters may slow the filling process, but will definitely keep tank cleaning to.a minimum.

[cascade]

Originally Posted by NorthCoastJoe

My tanks are cleaner than most people's cooking vessels. With inspection ports that I can climb through and really get inside. I would keep cleaning those until spotless.

Be very careful about putting your head in an empty fuel tank.
I know of two professional yacht crew who have died from asphyxiation after getting into a fuel tank.