CD36 fuel tank cleaning

[John Danicic]

Troy:

Not sure how I am going to proceed with a cleaning as I have not yet investigated the inspection port situation. I don't know what I have to work with, so your post was timely. It is unlikely that I will get to this job this year as I have just filled up and the season is coming to a close.

I have used the shop vac and a flexible plastic hose to clean the water tanks of sediment. That works well.

Your idea of a camera is intriguing. That and a attached light would at least help to find any lose concentrations of scale.
Think Colonoscopy!

As to cleaning my tank completely. Short of taking the tank out and doing what Ron M. did, I don't think I will get the tank very clean but clean enough. With good fuel filters and maintenance it should serve as it has served for years. Just a little cleaner. The Dahl filter is very large and as I found out, will hold a lot of crap before it plugs up. The vacuum was on the low end when I drained the filter so I still had more filter capacity. Then again, there is always the sails.

Sail on

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

[Troy Scott]

John Danicic,

Ha! Well.... (southern style pregnant pause).... I can't take credit for the colonoscopy idea. I have a friend who is a surgeon. He actually borrowed such a device from a hospital and used it to find a fuel leak in his airplane wing. Then of course it went BACK to the hospital and .....

[John Danicic]

Oh!

What with good sterilization techniques, it should be right for many years of use on its intended subject. I just hope your surgeon friend didn't put any nicks on the scope. That would hurt and drive the cost of health care up.

I am thinking one of those tiny camera and light deals attached to a vacuum hose. You could watch and direct the whole procedure on a high def TV screen from the cabin sole. Such luxury! And, if you do it right, you should not have to do it again for another 10 years.

Oh the depths we sink to for our boats!

Sail on

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

[Troy Scott]

Successful "operation". No nicks. No record. No charge. Depths indeed.

[Troy Scott]

Well...., Today we spent the whole day cleaning the 53 gallon diesel tank. I had previously removed the 4" inspection port and the fuel gauge which reveals a 1 3/4" hole. I ended up buying a pump-up sprayer ($20), several gallons of mineral spirits, a can of lacquer thiner, and a box of cleaning rags. I modified one of the spray tips to make it shoot a stream rather than a fan. It came with a "wand" extension and a long hose. We were able to "melt away" the majority of the gunk by spraying it repeatedly with the mineral spirits. We filtered and recycled the spirits three times. Each time we also used a paint brush taped to a dowel to scrub the walls and the sump. Finally it looked pretty good with the exception of a little stubborn crud in the sump. So we switched to lacquer thinner, which is a stronger solvent. This did a good job of dissolving the remaining crap. Finally we cleaned up and threw away all the rags which had served as filters and general crud catchers. We poured all the contaminated solvents into the recycling tank at the airport. I feel pretty good about that tank now. Next I'm going to make sure the holding tank and all the water tanks are OK.

[John Danicic]

Troy:

Good for you. How did you deal with the baffles if any? What did you use to remove the crud from the tank with? A shop vac, a drill pump?

Another thought. Will the lacquer and the sprits just evaporate from the tank or did you rinse that stuff out with diesel fuel?

I bet you feel good about not having to remove the sole and the tank.

Sail on

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

[Troy Scott]

John,

I have a specially modified wet-or-dry shop vac that I've been using on my boat project. All the dust is pulled through water, so the majority of the dust ends up in the water. Of course it will still suck up fluids. We removed all the fluids from the tank using a clear siphon hose. To start the siphon, I just held the low end of the siphon hose to the vacuum until I could see the fluid approaching the end, at which point I placed the end of the hose in a container to collect it. (I didn't actually pull the solvents into the vacuum cleaner.) There were only traces of the fluids left in the tank, and I'm sure they would evaporate since I've left things open. I will wash it one more time with just clean diesel right before I close it up.

With regard to the baffles, there are two, so there are three large sections. The baffles have fairly large openings, so it's fairly easy to get the "wand" from the sprayer through those openings. The sprayer can be used with or without the wand. I have a helper who is young, athletic, and resourceful. He managed to get the solvent stream to shoot just about everywhere, while I did my best to keep the sprayer well pumped up.

I think some tanks are probably a lot more cruddy than mine was. Only a few of the deposits were really difficult to dissolve. I understand that some folks have to bounce a chain around to knock stuff loose. The chain "heroics" were unnecessary in my case, but there was A LOT of crumbly brown sludge, easily enough to clog a large filter, so I'm glad the vast majority of it is out.

I may improve the filtering system when I reinstall the engine, but I'm not sure.

[David VanDenburgh]

Troy,

To begin the cleaning process on Ariel (before Davie installed the fuel polishing system), I bought a large plastic trash can and an electric-drill operated pump and pumped all the fuel out of the tank WHILE AGITATING THE TANK with a stick with a cloth swab on the end. When the tank was empty, I used the stick with a new cloth swab to get out the crud. I added a little diesel and frequently changed the swab. Ariel's tank has a fore and aft baffle in it so it was quite a trick to get the swab into all parts of the tank. I kept adding diesel, swabbing it out, dumping the dirty diesel, and repeating until the tank looked pretty clean.

Then I pumped the fuel from the trash can back into the tank but ran it through a "Baja" filter on the way. I agitated and swabbed some more, then pumped the fuel back into the trash can and repeated the process once more. By the time I had done this three times, I couldn't see anymore gunk in the tank or in the fuel.

A few months later, Davie built the fuel polishing system (described on Ariel's website). Now we flip on the switch and run the fuel through the filters and back into the tank every now and then. We haven't had a fuel problem since - about five years now.

Hope this helps.

[Troy Scott]

John and David,

David, your remark about agitating the fuel while removing it reminded me of one other thing we did: I extended the shaft on one of those paint-stirring propellers and ran this in a drill motor to keep the gunk in suspension while we sucked out the solvents. This is an important step because the gunk wants to settle to the bottom pretty fast.

I was surprised to observe that there is no "sump" per se in the tank. The whole bottom is one plane. The pick-up tube extends to just a little above the floor.

Folks, what about that four-year-old red-dyed diesel fuel? Would it be OK? How can I tell?

[Matt Cawthorne]

Troy,
You have spent a fair amount of time cleaning your tank. Why even take a chance with old fuel? What is your time worth? Would you put 4 year old fuel in your airplane, or for that matter, your lawn mower? When the military de-fuels their helicopters, the fuel is not returned to the fuel supply, even though it may be new. Granted, autorotating is a lot more dangerous than sailing, but then again, 40 gallons of diesel is a whole lot less expensive than the fuel for a large helicopter.

Our 1982 CD36 has the 43 gallon fuel tank that slopes back slightly. About 6 years ago I wanted to clean out the tank so I was letting the fuel run low intentionally so there would be less to take out. On the last sail of the season, just 5 minutes short of the dock, the engine ran dry. Once back at the dock, I looked in the tank and noticed that the tank was empty except for perhaps a pint of fuel. I was surprised at how well the system emptied the tank.

[Bob Condon]

I clean my tank every spring. Granted, I only have a 12 Gal tank on my 28' intrepid but saving $20-$40 is just not worth the pains that come with dirty fuel.

Here is what I do:

1. Take a 3/8" clear tube and place a brass fitting on the end for weight.
2. Through the filler cap, I run the tub in, brass tube first.

3. I take an compressed air nozzle and it it a few blasts to get the fuel mixed up. (I typically do it with less than 1/2 a tank of fuel.

4. WIth the tube in place, I grab the shop vac and start a siphon. This is done with care by holding the tube upright, put the suction to the tube and as soon as the fuel climbs up the hose to a few inches from the vac, in one swoop,remove the hose from the vac hose, and place in a 5 gal pail and watch what comes out...

After you lose the siphon because the fuel is pretty much gone, I filter about 1 gal of fuel using a funnel and coffee filter and place back into the tank, blow some are in, such the rest out with a siphon, give the fuel to a friend who can use it in his garage furnace (or the town barn) and fill tank with 12 gallons of fresh fuel. I change the racor filter every other year without issue...

This is all done on land at the house. God forbid the CG see you do this on the waterfront!!

Bob Condon

[S/V Necessity]

If you can find a shop that uses a furnace that burns waste oil, they will happily take old diesel, or just about anything for that matter.... Shops that have LOTS of old oil at their disposal often have these heaters (shops that service large equipment regularly.)

[David VanDenburgh]

I agree with Matt about retaining old fuel and should have mentioned that we had a full tank of new fuel added before we knew that the tank was thick with sludge on the bottom. (The sludge became a problem after a hard sail stirred it up.)

[Troy Scott]

Folks,

Today I read several online articles about diesel fuel problems. Those articles and the comments here have convinced me to discard the old fuel.

I want to clean the tanks one last time, using fresh clear diesel this time. I have found a "Suction Blasting Gun Kit" ($25 at Northern Tool + Equipment) which is what I really wanted when I bought the pump-up sprayer. This air tool should allow me to really blast the tank interior to get the last of the particles and any traces of solvent that may remain.

I'm seriously thinking of installing a simple fuel polishing system, since one tankful is likely to last me over a year. Have any of you come up with a simple, effective and not-too-expensive setup?

I'm also thinking of installing parallel filters on the engine intake line, with valves that would allow me to easily switch between the two. Have any of you done this? What parts did you use?

[David VanDenburgh]

Here's how we did it on Ariel: http://www.ariel-cd36.org/projects_fuelsystem.html