Cleaning Fuel Tank

Engines, Drive trains, Propellers, Steering, Ground Tackle and other mechanical system
midnightsailor
Posts: 140
Joined: Thu Aug 06, 2009 1:21 pm
Location: Greenport, New York

Re: Cleaning Fuel Tank

Post by midnightsailor »

Thanks folks for all the great help, suggestions and ideas, sure is helping me deal with this important maintenance project. I am seriously thinking of doing what plolic and others have done, that is, cut another opening in the tank to gain access to the other half beyond the baffle. Does a six inch opening seem adequate or wood 8 inch be better ? I should measure the opening already there, ha , ha, but I am at home and did not think of that while I was there yesterday, well, I will do that today. I will have to find a good sealent or gasket material, and I guess nylon or similar typr washers for insulating the stainless steel screws and also coat threads with tefgel. I am fortunate in one aspect since the tank is under the sole in the bilge so all I have to do is lift up the sole hatch and the whole tank is there, no cutting of plywood covering! The thought of ever havinvg to remove this tank inspires me to do my best to maintain its health. It looks like it would not be an easy job to remove it. I wonder if anyone with a F-33 has had to do this yet? I agree, Rick S. , that the fuel dryer is in fact just alcohol, just like the gas line anti-freeze sold for cars in the winter. Alcohol sucks up lots of water. Its a great dehydrating agent which I remeber using in biology class to dry out specimens for mountingon microscope slides. I also am suspicious of the starbright fuel treatment and tank cleaner in that they both sure look and smell the same...makes me wonder if theey just labled and packaged them differently or maybe just diluted one ,or concentrated one so they would have two different products......or is that just my suspicioius/skeptical side coming out? :mrgreen:
1982 Freedom 33 Cat Ketch, Hull # 53, Standard Booms, deep keel ,tall rig
An armed man is a citizen, An unarmed man is a subject. George Washington

rds
Posts: 50
Joined: Mon Jul 06, 2009 9:32 pm

Re: Cleaning Fuel Tank

Post by rds »

I did an extra opening in the fuel tank of my F44. with the intention to clean and inspect the tank from inside. my tank is 85 gallons and roughly consists of 3 sections so I've been thinking to make 2 more inspection ports but after cutting second port I concluded that all the dirt / water / gunk mostly accumulates in the lowest point, where the original inspection port is , so probably second port been done mostly for my peace of mind and I decided against the third one. The second section was much cleaner. The size of the original port is such that I can stick my whole arm inside the tank to get to all corners and clean it inside very nicely. I just pumped the oil out from the tank via the port into several plastic jars (about 30 gallons in total).
My neighbor is utility engineer, he looks after big oil burners on some plant. According to him the diesel fuel does not have any expiration. I let the oil sit in the jars for some time (probably 3 weeks or so ) so all water / sediments / e.t.c. went on the bottom 1/3 of jars . After that I pumped the approx. top 2/3 of fuel back into the tank via some cheap home depot filter with 10 microns cartridge.
Another thing is the water inside the tank. While I kept the tank empty and opened I could clearly see about 1 oz. of water accumulating in empty tank over night. My boat spent about 10 years on the hard with tank about half full and I could clearly see the line of corroded aluminum from the water accumulated inside the tank over the years…. I saw all of the corrosion in the first section (the lowest part of the tank. ). My tank is not leaking .. but I can imagine this could be a big problem… for now I cleaned my tank as good as I could , sanded it from inside and painted with some super penetrating, fuel resistant substance (I forgot what it is called , I still have that plastic container somewhere in the house so I can look it up , if someone interested) .
That has been done more than 2 years ago…. 2 seasons later .. I have not had any fuel related problems yet… (knock on wood)

Just wanted to add that I cut square opening, bough thick corrosion resistant aluminum plate and sheet of cork for gasket from mc-master. Secured everything to the tank with a bunch of stainless screws
Last edited by rds on Tue Apr 09, 2013 3:22 pm, edited 1 time in total.

Tricia
Posts: 107
Joined: Fri Dec 05, 2008 9:59 pm

Re: Cleaning Fuel Tank

Post by Tricia »

I got 2 Seabuilt access plates for my fuel tank and put one on each side of the baffle. They're a little pricey, but an excellent product and not hard to install. The 8" plates have a 6" cutout, which makes it really easy to get an arm in for cleaning, and to be able to see inside the tank with a flashlight. I sucked fuel out into Gerry cans with an oil extraction pump - put the hose through the fuel gauge hole. Then cut the holes with a 6" holesaw, and carefully wiped out residue and aluminum shavings. Poured fuel back into tank through a filter and measured it as I poured so I could mark actual levels on the gauge. Now I have a better idea how much fuel is actually in the tank.

midnightsailor
Posts: 140
Joined: Thu Aug 06, 2009 1:21 pm
Location: Greenport, New York

Re: Cleaning Fuel Tank

Post by midnightsailor »

Well, I went ahead a nd followed what some of you have done, I cut another access hole in my tank.! I measured the original and made a 6 inch hole with my Bosch recipricating saw...it was a bit tricky making the cut with the saw in the tight space but it came out just fine. I measured the tank wall thickness ,which is 1/8" and also measured the thickness of the original cover plate, which is 3/16" and also 8 inch diameter. I will use a local metal fabricating shop I have used many times in te past, to make me a 8 inch by 3/16" disc for my new covber plate. I thought of haviing them make me up some 2 piece semi-circular backing plates but since the originals are just tapped with machine screws into the tank walls I guess it is good enough since that has lasted over 30 years with out a problem. I will us plastic washers between the stainless screws and the aluminum tank.
There was a good amount of crud and debris in the second chamber so I am gla I decided to go ahead and add the extra opening. Tommoroow I will be mucking it out and cleaning it up with some clean deisel and drying out with alcohol, so I can then vacumn out and sand and pepples etc, that are left behind. I am not sure yet of what to use for sealing the plate to the tank...either a rubber gasket like the original or some type of sealant. Any suggestions? I have some fairly thich rubber from truck inner tube I could use to make a gasket but not sure if that is resiliant enough.
Boy, my boat hasn't ever been in such shambles! I have several projects going right now, all in various stages of completion...didn't plan it this way, meant to try to finnish one project at a time but things just came up and next thing I know I have part of the overhead down (so I can startt repalcing it) my Dickerson propane bulKhead mount fireplace partially installed, decided to get fancy and inset into the bulkhead and back with tiles, so \fabricating a "box" for the opening and will be laying tile over it. Making cardboard mock-ups of everything to be sure it all goes together with pleasing dimensions. My supercold machine is sitting in its opened box waiting its turn to be installed, and my cushions are nearly complete, have got all back from upholsterer except for port settee. Curtains and hatch covers will follow. This fuel tank project jumped straight to the head of the list as the good weather started getting closer and when I saw what the inside of the tank looked like! ....oh yea, and the sail-loft just called today to tell me my sails were ready for pick up.....I still have'nt removed the boat cover yet! So what place does bending the sails on take?
1982 Freedom 33 Cat Ketch, Hull # 53, Standard Booms, deep keel ,tall rig
An armed man is a citizen, An unarmed man is a subject. George Washington

plolic
Posts: 31
Joined: Sat Jun 26, 2010 11:18 pm
Location: Vancouver, Canada

Re: Cleaning Fuel Tank

Post by plolic »

While we own sailboats and sail a lot more than motor, we need to make sure our engine will run when needed in those rare moments when we really need it. My reason for opening the tank up, and i was more than glad I have, was that one bad experience coupled with another boat that was acting as a committee boat for a local race when the weather picked up and they could not start the engine (for exactly the same reason) and ended up blown on the beach as a total constructive loss, luckily no injuries. Any boat over 30 feet anchored and experiencing 30+ knots of wind and dragging anchor will only manage to move to safety with a reliable engine, and lets not forget that even a small amount of water and s..t in the tank will most likely act and clog the filters when the boat is rock and rolling in that seaway, and for an engine to run we need fuel. As I mentioned on my previous sailboat (Dufour 31) i had 17gallon SS fuel tank that I inspected and found as clean as glass out of a dishwasher, but the 35 gallon aluminium fuel tank on my 1986 Freedom 36 had a lot of crude and slimy grime all over the tank that i was glad to have cleaned it and can inspect any time I suspect or see sedimentation by opening the small hole where the level gauge is. to seal inspection holes I used slightly larger aluminium plates, ss screws and liquid (out of a tube) diesel fuel sealant. keep the tank full most of the time and not a drop of leak even in heavy weather and movements.

midnightsailor
Posts: 140
Joined: Thu Aug 06, 2009 1:21 pm
Location: Greenport, New York

Re: Cleaning Fuel Tank

Post by midnightsailor »

Those Seabuilt access are really nice pieces of hardware and if my budget allowed I would probably be using them. The 3/16" aluminum coverplate should work fine as that is how the original is done and other people have done it the same way.
Plolic, can you tell me where to find this diesel fuel sealent, is it generally available in most hardware stores or maarine chandleries ? Is there any brand name? thanks....oh and I definately agree with youir feelings about a reliable engine, exactly why this project has taken priority of all the others.
1982 Freedom 33 Cat Ketch, Hull # 53, Standard Booms, deep keel ,tall rig
An armed man is a citizen, An unarmed man is a subject. George Washington

plolic
Posts: 31
Joined: Sat Jun 26, 2010 11:18 pm
Location: Vancouver, Canada

Re: Cleaning Fuel Tank

Post by plolic »

i have used Permatex® Form-A-Gasket® No. 2 Sealant

midnightsailor
Posts: 140
Joined: Thu Aug 06, 2009 1:21 pm
Location: Greenport, New York

Re: Cleaning Fuel Tank

Post by midnightsailor »

Ah, yes, I am familiar with that , that should be a good choice, thanks
1982 Freedom 33 Cat Ketch, Hull # 53, Standard Booms, deep keel ,tall rig
An armed man is a citizen, An unarmed man is a subject. George Washington

Post Reply