Cleaning the fuel tank; an idea

[David Tabor]

Obviously a bunch of GUNK was jarred loose in the tank by our passage through the GS last week. Draining the tank revealed quite a bit of black gunk. I freed the tank from it's aft cabin prison and it's sitting in my shop now.  Years ago I took the tank out of my CS36M and had it cleaned at a radiator shop.

Now I'm not sure where or how to clean this tank with the baffles preventing ready access to parts of the tank.

I'm considering using a quart or two of kerosene with a couple of handfuls of BB's thrown in the tank and then agitating the tank to allow the BB's to scour the surfaces of the tank, rotating the position of the tank as necessary.

Any idea why this would not work?

[Bud Cary]

I’d want to count how many BB’s I put in the tank and how many came out … wouldn’t want a stray one or two to end up in the fuel line

 

 

 

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[Michael Moradzadeh]

Steel bbs, and pick them up with a magnet.  But I'd think a long-handled brush would be better.

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[Wayne Cassady]

Did a similar cleaning on our previous boat, a Cal 33. If you are patient, the kerosene alone will likely do the cleaning with lots of agitation. Do a few iterations and see if the kerosene is getting cleaner each time.

Sent from my iPhone

On Jul 10, 2025, at 10:13 PM, Michael Moradzadeh <m...@yachtpc.com> wrote:



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[David Jade]

We had someone clean out a tank with bad fuel. Their setup was to use the fuel itself to power wash the tank. They had a setup that first suck it out and ran it through a series of filters. Then some sort of spray nozzle on a hose they could feed back into the tank to wash it using the now filtered fuel. It recirculated like this as they cleaned it, then they discarded the old fuel. 

David                      _/)

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On Jul 11, 2025, at 6:53 AM, Wayne Cassady <wayne.c...@gmail.com> wrote:

 Did a similar cleaning on our previous boat, a Cal 33. If you are patient, the kerosene alone will likely do the cleaning with lots of agitation. Do a few iterations and see if the kerosene is getting cleaner each time.

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[Ed Sitver]

I would guess that fuel tanks in boats are baffled, which would impact physical cleaning methods such as brush or maybe bbs. I don’t know if the J tanks are baffled, but if anyone knows, I’d like to hear. 

Ed

[David Tabor]

Yes, there is a baffle inside this tank.  Even with an articulating wand to spray and rotating it I'm not sure how clean it would get.  Would definitely need to stick an endoscope in there and look around.  Hence my thought of using something to scour the inside but not damage the tank.  (Got the idea remembering how I cleaned algae out of old bottles I found by using sand and shaking them.)

[Todd Stevens]

FWIW, after stirring up a lot of gunk, crossing the Columbia River Bar, I did an emergency clean-out/“polish" in the field using a little plastic hand pump (from an auto parts store) and a Baja filter. Sailed another day, more stuff came out from behind the baffles. Repeat procedure.

Todd
J/42 Wild

[Ches Upham]

Our J40, Velella, had a lot of gunk (not diesel bug or bad fuel) that had built up over the years. We had it cleaned by a group in Blaine, WA. They cut a hole, polished the fuel by running it through a set of filters to a large drum on the dock, and scrubbed by hand. 

I believe there was only one baffle in the center of the tank (see photo), but had enough room to pass under it to scrub well enough behind. Plus, it drains to the front bottom where the access port was installed, so the gunk flowed there. 

Attached are photos of before and after with the baffle. It totally solved our problem, and now that we have an access port, I will clean myself in the future. We were having to replace fuel filters with increasing frequency. I have a bunch more photos I can send if anyone wants to see more.

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