To Polish and Clean Diesel Tank or Not?

[Capt.Don]

Hi,
I've read all the discussions on cleaning, polishing, additives, etc. I'm looking for input on whether I should spend the money having my tank cleaned and fuel polished.

I just inspected our 25 gallon diesel tank and found a small amount of black / brown sludge in the bottom of the tank. I pumped out 2 gallons of fuel before taking the pictures. The extracted fuel seems a bit cloudy. The first picture shows the sediment at the bottom of the tank, with the red squiggly lines probably from my hand-pump or paper towel (red diesel fuel). I'd say this layer is very thin, less then 1/32". The second picture is the side baffle, where there's some black goo on the sides, to the left of the lettering, above the fuel level.

I've never had any fuel problems, nor have I seen any crap or water in the primary Racor filter. In fact, I was surprised by how clean this looks.

We are planning a trip to Mexico and back, later this year. Should I clean the tank and polish the fuel?

Any reliable mobile fuel-polishing services in Long Beach CA?

Thank you,
Don

[DeepFrz]

YES. Believe me you do not want that stuff floating around in your tank if you hit rough seas...and you will hit rough seas. I have seen that stuff plug a fuel line. The only time I was sea sick.

[Snowpetrel]

Pump it out and clean it by hand if its a small tank.

[SV Lift]

That doesn't look that bad, but I would absolutely clean it.

You need to physically scrub the tank (which looks easy- small tank with good access!). Fuel polishing without scrubbing can only do so much. Maybe just run it low, pump the last few gallons into a jug and go to town with a brush.

[Capt.Don]

That's kinda been my plan but I was hoping it was OK. There's about 4 gallons in the tank after pumping out some to inspect. Everyone's convincing me that I should take the time to clean the tank. I understand scrubbing and cleaning the inside. It is a small tank and I have two 6" inspection ports so this should be pretty easy.

The next question is what about the fuel? The gallon or so that I pumped out looked pretty cloudy (dark red). I'll check it tomorrow to see if the goo settles to the bottom. If so, I can probably siphon the top portion from the jerry cans back in the tank. Or should I have the fuel filtered (anyone with a portable fuel polishing system in Long Beach CA)?

I want to change the fuel filters soon, though I don't want all this stirred up crap in my new set of filters. Should I wait a few engine hours before changing filters or doesn't this matter?

Just a side question - will I need to bleed the fuel line after emptying the tank?

Thanks everyone - you are persuading me to clean the tank!
Don

[Snowpetrel]

We filtered a big tank full, at 250 ltrs through strong paper towels in a funnel. Seemed to work fine, but may not be worth the hassle for the small amout of fuel you have?

[Capt.Don]

Originally Posted by Snowpetrel

We filtered a big tank full, at 250 ltrs through strong paper towels in a funnel. Seemed to work fine, but may not be worth the hassle for the small amout of fuel you have?

I can do that..... thanks for the idea.

[crazyoldboatguy]

Scrub the tank. Polish or discard the fuel. The culprit is the moisture that gets into the tank either from contaminated fuel but also from the entry of humid air into the tank as you use the fuel or from expansion and contraction of the air in the tank during the course of the day. Keep your tank as full as possible at all times. Using fungicidal additives can keep the flora to a minimum (after a thorough cleaning and polishing) and consider a true fuel polishing unit to remove the water and clean the fuel (gulfcoastfilters.com) sell drop in units. That's the type you need for true polishing. You can cobble the parts together yourself as well. I am not connected to the company in any way - I think they know what they are doing.

Don't just put some additive in now. You already have a problem that will plug your fuel system after it gets bumpy during your sail. Once those filters are plugged up while under way - things will get hairy fast.

[DeepFrz]

I suggest you run the fuel through your filter after you clean the tank and replace the filter element when you finish. Buy a small electric diesel fuel pump and just recirculate the fuel through your filter until it looks clean. Change the filter element and you should be good to go. You don't have enough fuel to make it worthwhile hiring a professional to do the job. The purchase of the pump could even be the start of a fuel polishing system.

You will most likely need to bleed the system when you are done.

[Capt.Don]

Originally Posted by DeepFrz

I suggest you run the fuel through your filter after you clean the tank and replace the filter element when you finish. Buy a small electric diesel fuel pump and just recirculate the fuel through your filter until it looks clean. Change the filter element and you should be good to go. You don't have enough fuel to make it worthwhile hiring a professional to do the job. The purchase of the pump could even be the start of a fuel polishing system.

You will most likely need to bleed the system when you are done.

Now I need to go back and read all the DIY fuel-polishing posts I like the idea of cycling the few gallons I have through my filter and then changing. On a positive note, I can watch the fuel vacuum gauge register!

[Kenomac]

Get rid of the fuel, clean your tank and start fresh.

[SailRedemption]

Originally Posted by Kenomac

Get rid of the fuel, clean your tank and start fresh.

This. If it's truly a few gallons, less than 10 is not something to spend money on a polishing system. My opinion, clean the tank well and flush the lines out and clean the racor(get a service kit and change out the replaceables) then put a new filter in. Get new fresh fuel. It probably took a long many years to get that sludge down there so the money spent on a polishing system could be used for other things, especially for such a small tank.

You could get another spin on filter with the current filtration as the racor and then get a finer racor filter and still save money from buying a polish system. Saves room, money, and time.

[lorenzo b]

In my experience it all depends on where you live. Here in Panama the air temp is always around the same as the water temp so you get no condensation inside your tank and my diesel, 2000 gls, is fine year after year.
If you're in New England you're going to get sludge.
For the quantities you use I would consider a day tank.

[Greg4cocokai]

Don, you can check at the fuel dock in Alamitos Bay. Was a guy Kenny that did fuel polishing and ran Vessel Assist. Great guy and very helpful. Good luck and maybe see you in Mexico!

[crazyoldboatguy]

lorenzo b,

It would also depend, I think, on where your tanks are located in the boat. If your tanks are low in the hull, I think your claim of steady temps are valid. However, some sailboats have tanks under cockpit seats or up against the hull above the waterline and they would be subject to the direct sunlight beating down on the structure right next to, or above it. That would very easily raise the temp of the tank contents, fuel or air, and could cause condensation to form. Plus, as a motor vessel, you are more likely to be using larger quantities of fuel regularly, whereas a sailing vessel may go weeks and months with a half full fuel tank and not be using it at all until they are being pushed on a lee shore in heavy weather with the tank stirred up and the filters filled with gunk. Apples to oranges