CD36 fuel tank cleaning

[Troy Scott]

Folks,

I've known for some time that I need to check the cleanliness and integrity of the tanks under the sole before I continue with finishing the interior. Today we managed to remove the inspection cover from the aluminum diesel tank. I say "managed" because the inspection plate is not aligned in a way that would encourage it's use for purposes of inspection or even easy use of a screw-driver, as the plate is offset from the opening in the cabin sole. I can see a little of the tank interior by using a mirror. We have siphoned out the 35 or so gallons of fuel. The fuel seems pretty clean, even though it has sat for about four years. The bottom of the inspection plate is "cruddy" with sticky brown flaky stuff. I want to clean the tank interior and return the diesel to the tank. I know that mineral spirits on a rag would do the job, but I'm not sure I can reach the whole interior for a wipe-down. I read the fuel polishing article from the ARIEL website, and I read about a CD27 owner's cleaning using simple green and hot water. I'm interested in suggestions for how to clean the tank. I'm also interested in advice about how to make sure the "old" diesel is good, clean and stable before I return it to the tank.

[tartansailor]

The best way to clean a fuel tank is to:
Remove it from your boat,
Put a long length of chain inside,
Tumble it, remove the chain and drain,
Flip it up side down, insert a steam wand and power wash.

The old diesel is good as long as it is crystal clear.

Dick

[Troy Scott]

Thanks, Dick.

I REALLY don't want to remove the fuel tank. I just want to clean it. Surely there is a good way to do it in place. Anybody?

[Russell]

If your cabin sole is in good shape and the tank is not leaking, absolutely it is north worth it to remove it. I have heard of in place steam cleaning, but I am not sure how its done. Since you have already removed the old fuel, I would just do the best I can with a long stick with a rag tied to the end soaking in mineral spirits or acetone. Its an aluminium tank so you do not have to worry about rust flakes that mild steel tanks have. The concern is caked crud from algae growth over the years, but even that I think is minor. The major issue in fuel tanks is the loose stuff, dead or live algae and crud, having removed your fuel you likely got most of that out already.

I would setup a fuel polishing system with a 12v fuel pump and racor filter, and use that setup to take your old fuel and spray it into the tank at the same time you are extracting (dump a couple gallons in first so the pump can prime and have something to suck out). This way you agitate any loose crud you did not get out initially so it can be sucked up by the pump and passed through the filter.

As for the old fuel, likely it is fine. Even if not crystal clear. You want to polish it reguardless before putting it back in the tank. Right after polishing it should be well agitated, take a sample in a glass jar, set the jar aside and wait a day or two and check it, any sediment at the bottom of the jar? If not, your fine, if so? May want to get rid of the duel or repolish and check again. With age the fuel does darken, and even more so with dyed fuel, it does not mean its bad fuel though.

For what its worth, when I repowered, I went through most of the above process, my old fuel was very dark even though I had been actively using fuel for years before then, but I put it back in on the assurance of the mechanics. After polishing the old fuel, cleaning the tank and installing the new engine, my fuel now is always light colored and clean (after a number of hours burning off and continually diluting the old dark fuel).

Old gasoline is another story, but your old diesel is likely fine once you polish it, even if it still looks dark.

[Jim_B]

On my 43 gal. tank there are three possible openings 1). fuel gauge float, 2). 4" opening and 3). very far up toward the bow a smaller 2" port. Only the fuel gauge is easily used the others required a stubby and 'horizontal' philips head screw driver to remove and a very flexible arm/elbow to access.

There was a baffle ~8" forward of the 4" opening. This baffle has a 2" hole ~ 12" from the top. There were also cut outs and weep holes in the bottom corners of the baffle. The other observation is there was a recess in the tank just below the fuel pick up tube (again this was on my tank - yours may be different).

Using these various access points, a temporary pump system and various 1/2" PVC pipe wands hooked to flexible tubing, I was able to get a lot of crude out of the tank and the fuel is closer to the nice pink color with each each fillup. (I had about 20 gals in the tank).

Keys to success:

1) putting in an additive that broke down and released the slim from the tank sides (I can't remember the name of the additive used).

2) using a 120 volt pump - had to really keep the liquid flowing to keep the crude suspended for pickup (initially tried a 12V pump)

3) utilized all the access points in various combinations of fuel flow direction/dispersion. (esp. pumping high volumes of 'return' fuel into the front section with the pick up in the aft recessed section).

4) used a series and combination of filters - including a large Sears water filter that had relatively cheap filters (I probably use a dozen filter elements).

5) the whole process ran over 4 days

So much crude came out - I'm amazed that I didn't have major fuel issues. Just fortunate I guess.

Good Luck

[Troy Scott]

What about this thing?

http://www.diesel-fuels.com/algae-x/mag ... oning.html

[sharkbait]

Ethanol will dissolve almost anything you have in the fuel tank including the varnish deposits on the sides and top. Use plenty of ventilation. Put it in the tank and seal the tank for a couple of days.

Then suck out all of the crud you can. After that put in a few gallons of diesel and start flushing. I used a gear driven pump that pushed 20 gpm @ 40 psi. I made a series of wands, 1/4" stainless tubing, in various shapes to reach into all the corners. All of this was pumped through a RACOR 900 with a 30 micron filter. I was drawing the fuel through the normal fuel pick-up and returning it through the wands to spray every corner of the tank. After cleaning the tank all of the old fuel was returned to the tank by sucking it out of the containers with the pump through the RECOR with a 2 micron filter and back into the tank. Fuel looks good and the engine runs fine.l

[Bob L]

What about this thing? l

Years back there was a heated discussion of this product on the CD board. As I remember, it was ineffective.

[Troy Scott]

If I could temporarily put something like mineral spirits into the tank and get it moving a lot, maybe with a paint-mixing propeller on a drill motor, I think this might be effective. But many gallons of mineral spirits would be quite expensive. Would something cheaper work? Is there a product especially for this purpose?

The sides of the tank and the baffle (where I can see) look OK. The crud I observed is on the underside of the aluminum inspection plate, and it isn't completely covered by the brown gunk. I haven't yet found a way to observe the sump. I'm thinking the problem is not as bad as some may have experienced, but still, while the boat is in refit seems the time to tend to this.

If I were to decide to pull the floorboard up to facilitate removing the tank for cleaning, is this as straight-forward as it seems? It looks to me like I would have to remove some plugs and unscrew the perimeter, after which it would just come up. Is this correct? Or is this the proverbial "can of worms"?

[Russell]

What about this thing?

http://www.diesel-fuels.com/algae-x/mag ... oning.html

Snake oil IMO

[John Danicic]

After a, rolling 19 hour motor sail and a 340 mile trip where the motor was run 2/3rds of the time, I drained my secondary Dahl fuel filter and found flaky black stuff in the discard tub. All the particles were black and fairly uniform in size and shape.



The filter did its job and the engine never faltered but I decided the next time my tank is less then half full I intend to pump out the remaining fuel and somehow, clean the tank of any more sediment. What do people think of using an old wet vac and a snaky hose? I will then replace the fuel by filtering it through a West Marine funnel filter.


Sail on

John Danicic
CD36 - Mariah - #124
Lake Superior - The Apostle Islands
CDSOA # 655

[sharkbait]

When you open that tank you are going to find a lot more than what I see in your picture.

[Troy Scott]

John Danicic,

That "somehow" is what I'm interested in. Do you have any ideas? I want to clean mine out, but I haven't had any brainstorms yet. I bought a new mop thinking that I'll swab what I can reach with it, but obviously I can't reach through the baffles with it. I can say for certain that mineral spirits on a rag will readily wipe off the offensive brown stuff. I suspect that if I could afford to temporarily fill my tank with mineral spirits and swish it around a little, it would handily dissolve all the brown stuff. But that would be ridiculously expensive and it would present a disposal problem. What might work nearly as well is the mineral spirits spray wash that aviation mechanics often use. It's just a garden sprayer kind of thing that sprays small amounts of mineral spirits to wash away spilt or leaked fluids. I suspect that if the wand were inserted into the tank through the various openings, the directed spray might easily wash the brown stuff to the sump, and from there it could be sucked out and discarded. Has anyone tried this idea? Thoughts.

I'm also wondering about a camera that might go into the tank and allow me to see what's going on in there. Thoughts?

[Troy Scott]

Has anyone tried this Star Tron fuel tank cleaner? It's a lot more expensive than mineral spirits, so it must be a lot better

http://www.jamestowndistributors.com/us ... nk+Cleaner

[Ron M.]

Yeah Troy I used it a couple of years ago.........It worked well @ 40.00/gal
I had my tanks out and fabricated a 6" inspection port in each one. This facilitated cleaning immensely. I don't think they had been cleaned in 30 years.......quite a bit of crud in them. I swabbed most of it out with rags and a pole. I put in a gallon or so of clean fuel and a couple of feet of chain and rolled them around the yard......that really got them looking good, the metal was beginning to shine on the interior. I then used Startron tank cleaner per their instructions. They were as clean as a whistle. I don't know if I'd use it again, kind of pricey, and I think you can get them very clean with methods described. I have been using their diesel additive also.
I don't know if you have inspection port or the access to add one. Seabuilt Co. makes an add on plate access system that looks pretty good for approx. 150.00. Like I mentioned, I made my own, but I work for free.
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