Need advice, please, on aluminum diesel tank repair

[Frank Langer]

Hi,
As in so many of our 1980s boats, my 1984 E30+ aluminum diesel tank is beginning to leak/weep/sweat at the very front end bottom middle V, not enough to drip but too much to ignore. I plan to empty the fuel, cut an inspection port as per videos and posts on this site, clean with acetone, then repair in place. Local shops are wishing me luck, but refusing to recommend what sealant to use, I'm sure out of liability concerns. I had planned to use epoxy and cloth, but was advised not to do that as diesel melts epoxy over time. Another mentioned having heard of "liquid metal", but doesn't sell it.
In short, what would you suggest as the best repair material for this minor, but worrying, leak?
Also, for the metal cover on the inspection port, do I need to tap the tank holes, or can I just drill slightly undersize and use sheet metal screws?
Thanks for any advice!
Frank

 

[nquigley]

I can strongly recommend these inspection ports:

Seabuilt - Access Plate Systems

I installed a 6" and an 8" port in my tank (either side of the baffle) when I had to do the same repair - mine was easier as I was able to get my tank out and take it to a metal shop. Good luck!

 

[1911tex]

Stow it!!! Get a marine bladder fuel tank. We used FAA equivalent in aircraft wings for many decades...no problems and it will outlast your use by a long shot. Many sources, many sizes...here is one>>>

Ready Pillow Style Marine Fuel Bladders | ISO 9001:2015

Extended Range Marine Fuel bladders. Extend your fishing range or repair a leaking tank. Marine Bladders by Ready Containment, LLC

www.readycontainment.com

 

[Jerry VB]

No personal knowledge, but Nike (Untie the Lines / White Spot Pirates) used "Splash Zone" by Pettit on her aluminum diesel tanks. She said Pettit said it was OK (YouTube) to repair diesel tanks.

 

[Dave G.]

As you know Frank I plan on repairing my fuel tank and planning to use epoxy/glass as my research has shown this to be a valid long term repair.
So curious where you heard that diesel will degrade epoxy ?

 

[Chris Mc.]

“Proseal” is what is used in the aviation community and it is excellent for 100LL and jet fuel so, diesel shouldn’t be an issue.

I’ve never heard of diesel degrading epoxy. But it is known ethanol will degrade fiberglass fuel tanks.

 

[Frank Langer]

Thanks for the replies so far, and I'll look into those various products. Dave, a staff at our local Industrial Plastics store, which sells lots of fibreglass products, cautioned against epoxy and cloth, as he said diesel will soften epoxy and degrade it. I had never heard that. A local radiator shop used to use a coating of some kind, but has stopped doing that and only welds tanks now if one can bring it to their shop.
I'll empty fuel from the tank this weekend and then measure to see if it can be removed through the cockpit locker, or if I need to use one of the recommended products for in place repair.
Keep those great suggestions coming!
Frank

 

[bigd14]

Frank, the fuel tank should come out through the lazarette. Mine took a little wrangling, but wasn't a problem. Sorry to hear of the leak. No fun. Or, maybe its a great time to make that quarterberth bulkhead removable for unfettered access!

 

[Dave G.]

If I could have got my tank out whole I would have considered replacement for sure although a much bigger job & the cost would be much more than repair. I'm guessing you guys with the 30+2's(post hull #632) either have shallower smaller tanks and or huge lazarettes ? I'm still going to do the epoxy repair on mine and hopefully they won't start putting ethanol in diesel fuel anytime in the near future.

 

[Loren Beach]

If I could have got my tank out whole I would have considered replacement for sure although a much bigger job & the cost would be much more than repair. I'm guessing you guys with the 30+2's(post hull #632) either have shallower smaller tanks and or huge lazarettes ? I'm still going to do the epoxy repair on mine and hopefully they won't start putting ethanol in diesel fuel anytime in the near future.

One cautionary note -- the diesel that we generally have available has quite a concoction of chemicals in it, altho less than the version sold for "off road" use. Marina fuel docks often have the 'off road' version for sale, as do some truck stops.

 

[Dave G.]

I guess we'll never know what they decide to "refine" fuel with but the worst thing that can happen is it will start to leak again IF they add something akin to ethanol. They build fiberglass diesel tanks with epoxy resins so I'm not concerned with the epoxy it's all about getting a good bond to the aluminum.

 

[Frank Langer]

I guess we'll never know what they decide to "refine" fuel with but the worst thing that can happen is it will start to leak again IF they add something akin to ethanol. They build fiberglass diesel tanks with epoxy resins so I'm not concerned with the epoxy it's all about getting a good bond to the aluminum.

Dave,
I'm hoping to drain the fuel tank this weekend, then cut the inspection port and decide if I'll try to remove the tank or repair in place. So far, Proseal 890 that's used in airplane fuel tanks seems most appropriate, but it's expensive. JB Weld Marine is also mentioned often with success, and is much cheaper, but I don't want to have to do this repair again. Pettit Splash Zone also got good reviews. I'll phone the various tech people on Monday for further advice on their product.
Frank

 

[Dave G.]

Frank,
I know Ed Knebel here on the site repaired his tank with epoxy and FG about 10 years ago and it's still holding. I don't know what brand epoxy he used but I'll send him a message and see if he remembers. I can tell you that the folks at West Epoxy have been selling epoxy to repair aluminum boats for a long time so I think they would have a pretty good product for this application. They also say they have many satisfied customers who used their product exact repair. I don't know what Proseal 890 is, is it a epoxy or ? I wouldn't use JB Weld products for this just because I've used their automotive products in the past and was not impressed. Let me know what you find out as I still have to wait for warmer weather before I can do the repair.

 

[Dave G.]

Frank,
Ed said; "West system epoxy 105 with regular 206 hardener". I'm planning on using West 650 per their recommendation for this repair.

 

[markvone]

Frank,

Just a thought.
If you have enough access to the top of the tank, still in place, to add access ports, can you add a large enough access port (8 inch?) above the repair area so that a welder can repair in place?

Mark

 

[Frank Langer]

Hi,
Thanks for all your helpful replies on this project. I've made good progress over the last three days since I started. For those who haven't had to do this, it is a significant repair, but I'm very glad so far that I haven't had to hire help at going rates of $90 per hour, or more.
I started by turning off all AC and DC electricity and closing off water tanks. Then I drained all the engine coolant which also runs thru the water heater. Then I drained the water heater of water, undid the cold and hot water connections and the electrical connections, unbolted the water heater and was able to lift it out of the cockpit locker.
I unscrewed the locker floor board, had to remove the start battery and whale gusher pump and it barely fit out through the locker opening. I'll trim it a bit before I reinstall it for an easier fit.
I emptied the almost full fuel tank, unscrewed the 5 screws holding the flanges down, then removed the fuel fill, vent, engine fuel return and main fuel line.
The 23 gallon aluminum fuel tank was lighter than expected, and I was able to lift it, turn it and pull it out thru the locker opening with a couple inches to spare. It measures 28" x 24" x 13".
Inspection of the tank was surprising. It's 36 years old, but was almost totally clean inside, only the odd little fleck of brown stain on the inside bottom, no rust anywhere inside or outside. The aluminum is thicker than I anticipated, quite robust, and the welds all look good.
There is a thin strip of green epoxy, about 1/4" wide and 2" long right at the front bottom tip where the tank rested on the stern tube. A tiny chip in that epoxy, about 1/8" is likely where my very slight leak was. I probably could have resealed it with marine tex or similar epoxy applied from the outside/underside of the tank, and saved myself lots of work. However, it was important for me to be able to inspect the tank properly rather than just patch it, so I don't regret the approach I've taken.
I will take the tank to our local radiator repair shop where they will inspect more carefully and weld that front bottom spot for a permanent repair.
As the water heater is at least 15 years old I've ordered a new 6 gallon Kuuma replacement, may get the heat exchanger cleaned, inspect and replace any coolant or fuel hoses as needed and fill with new diesel rated coolant.
Once I've got it all put together again next week, I'll go sailing again!
I know several others on this site are contemplating this repair, so this information may be helpful. Feel free to ask if there's something I haven't covered.
Frank

 

[Christian Williams]

Excellent. All our boats need to be taken apart after all these years, just to confirm they're stood the test. I installed a Kuuma heater, it worked well, there's a blog entry on it.

 

[Frank Langer]

Thanks, Christian! I read your blog on the water heater replacement, and have a better appreciation now for my old Seaward water heater fitting thru my locker without needing demolition.
I'll be pleased when my fuel tank repair project gets done this week and I can go sailing again. But although it's been alot of work and problem solving, it's also renewed my confidence in my amateur repair skills, and allowed me to see the hull underneath the fuel tank, an area that was new to me.
Frank

 

[Dave G.]

Great job Frank ! I am always amazed at how the people on this site just get things done. Well now you are steps ahead of me for sure but can't control mother nature. I have a couple of questions, so your tank was screwed down ? Mine is glassed to the hull. Do you think that small patch of epoxy was a previous repair, was it on the inside or outside ? Sorry couple more, was there already an inspection plate installed and is there a baffle ? One more request, next time you are at the boat, take a picture of your locker opening for me as I'm amazed at the difference our boats have.

 

[Frank Langer]

Hi Dave,
The locker floor was simply screwed into a lip on the hull liner with about 8 one inch screws. The tank was also just held in place with 5 hefty screws through metal brackets that are welded onto the tank. Neither was glassed to the hull liner. The small epoxy patch was on the outside and might have been a previous repair, though I have owned this boat for 15 years now. I can't explain why the small piece resting on the stern tube was chipped, as the epoxy feels very hard and the epoxy was resting on the fibreglass of the stern tube where it can't move because the tank is screwed in place--a puzzle. There is no inspection plate, but the fuel tank sender, which indicates amount of fuel in the tank, is attached to a small about 2 inch diameter plate held in place by 5 screws and a gasket. It was easy to remove, and gave me enough of an opening to shine my flashlight inside the tank for a quick inspection. I haven't decided yet if that will be a sufficient inspection port or if I will cut out a larger one as I had initially planned. Given how clean the tank is, and that this 2 inch opening would allow me to drain the tank if needed, I'm not sure it's worth the effort to cut a larger opening, but I'll still think about that before I reinstall it. I didn't notice a baffle in my quick inspection, but tomorrow I'll check inside the tank with my extendable mirror and get a better look.
I will try to post a picture of the locker opening as you request, but I'm not great at posting pics on this site (only have limited experience a few years ago, and the site has changed since then). But I will try to remember to at least measure the size of the locker opening. As I recall from earlier, I think it is 15". My hot water tank is about 14" and barely fit through; the fuel tank is 13" deep, and fit through more easily than I thought it would.
From my experience in the last three days, and assuming your boat is similar for access, openings, etc., and from your earlier pictures showing about 2 inches of rust/pitting at the front end, I would lean toward doing what I have done, to remove the tank and have it repaired (or replaced with a new one from the same manufacturer or someone who can replicate it). While it's always a bit worrisome to launch into a project like this, there is a benefit to knowing the repair is good and will last a long time. I have no special mechanical skills, but have managed this and similar repairs by planning carefully, working methodically, taking pictures and notes along the way, pausing periodically to think it through again to see if I've overlooked anything. Also, I'm almost 70 years old, though still in pretty good health. So if I can do it, most people would be able to.
Frank