Leaking Diesel Fuel Tank: Repair or Replace?
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This is a common problem for S2's of your vintage. Mine started leaking too and my water tank failed shortly thereafter...although leaving water with some bleach in it to sanitize it probably finished it. The previous owner pulled the tank and fixed it temporarily with epoxy. I wish I had known he was going to pull it as I would have shipped him a poly tank. It is still on my to do list. Leaks were at the front weld at the bottom as well as under the mounting straps at the bottom.
the perfect answer to your problem is a product called POR 51...... it is a lifetime repair and I have used it many times.... its not cheap, but its very affordable compared to a new tank and you never have to worry about it leaking again.
its a one part liquid and thick like paint. it adheres to the metal like epoxy, but its flexible, super tough and is about 8-12 mils thick when cured. its used a LOT by old car restorers to repair oem tanks that are beyond all other hope. the company that makes it is highly rated for their quality products.
you need to remove the tank, clean it out and let it dry..... then tape over all the holes, inlets and outlets except one. then pour the product in, tape over the hole and roll the tank around to coat the entire insides..... pour the excess back out and let it dry for a few days... I use a boot dryer with a hose connected to it to stick in the tank just to create air movement and displacement so that the carriers will evaporate out of the product quicker.....
one tip I will pass on for quicker coverage..... it comes in a one quart container and due to the thickness it can take a while to coat the entire insides with one quart.... i buy two quarts and then it spreads around quickly as you roll the tank..... and when you pour out the excess, it can be saved and used again on another tank...... or you can use it to apply a second coat but its not necessary.
its a one part liquid and thick like paint. it adheres to the metal like epoxy, but its flexible, super tough and is about 8-12 mils thick when cured. its used a LOT by old car restorers to repair oem tanks that are beyond all other hope. the company that makes it is highly rated for their quality products.
you need to remove the tank, clean it out and let it dry..... then tape over all the holes, inlets and outlets except one. then pour the product in, tape over the hole and roll the tank around to coat the entire insides..... pour the excess back out and let it dry for a few days... I use a boot dryer with a hose connected to it to stick in the tank just to create air movement and displacement so that the carriers will evaporate out of the product quicker.....
one tip I will pass on for quicker coverage..... it comes in a one quart container and due to the thickness it can take a while to coat the entire insides with one quart.... i buy two quarts and then it spreads around quickly as you roll the tank..... and when you pour out the excess, it can be saved and used again on another tank...... or you can use it to apply a second coat but its not necessary.
We successfully repaired such a tank from a '78 Hunter 33. entire bottom was corroded with one pinhole through and many pits and incipient pinholes. Sidewalls had about an inch of corrosion. Owner said he did not need all of the tank capacity so we cut off the bottom inch-and-a-half and welded a new bottom plate onto the corrosion free walls.. Corrosion had been caused by a leaking fuel fill cap letting lots of water in. That was 10 years ago.. no further corrosion because we stopped the water ingress. A poly tank is the best fix, but a good, well thought out repair is pretty good too. I have seen POR 51 used in cars and motorcycles, but I don't have any long term experience.
Another option is to wrap the tank in fiberglass and epoxy .. I don't like that one because as the aluminum corrodes, it will generate some great pockets where algae and water and other nasties can hide.
Another option is to wrap the tank in fiberglass and epoxy .. I don't like that one because as the aluminum corrodes, it will generate some great pockets where algae and water and other nasties can hide.
Bought a new aluminum 12 gallon tank from www.miraxfuelproducts.com for $264.00 including shipping. USCG approved and direct replacement for my Oday 27. Problem solved.
Tank dimensions are a problem...
I've looked at a few suppliers of pre-made aftermarket aluminum and poly tanks, including Moeller, Mirax, and Krakor. My current (OEM) tank is 8 gallons, and measures 14" x 14" x 10". That 10" is important, since the tank has to fit though the lazarette, which has 12" opening. Also, the footprint can really only accommodate maybe 2" more length.
Anyone know of a supplier of off-the-shelf 8 gallon tanks? I can get one custom made by the OEM supplier, Florida Marine Tanks, but I don't really want to take out a second mortgage to do that....
I've looked at a few suppliers of pre-made aftermarket aluminum and poly tanks, including Moeller, Mirax, and Krakor. My current (OEM) tank is 8 gallons, and measures 14" x 14" x 10". That 10" is important, since the tank has to fit though the lazarette, which has 12" opening. Also, the footprint can really only accommodate maybe 2" more length.
Anyone know of a supplier of off-the-shelf 8 gallon tanks? I can get one custom made by the OEM supplier, Florida Marine Tanks, but I don't really want to take out a second mortgage to do that....
I second this product. This stuff is pretty darn good & can be bought at a decent auto part store. A buddy of mine used it on his fuel tank on his backhoe 5 years ago & it's still holding. I've just used it to seal pinholes on our water lift muffler.
POR 51 Question
So...any suggestions about how I keep the POR 51 from fouling up the fuel pick up? I don't think I can remove it from the tank because it is welded in (although I haven't tried to remove it yet, since the tank is still in the boat.)
Thanks.
So...any suggestions about how I keep the POR 51 from fouling up the fuel pick up? I don't think I can remove it from the tank because it is welded in (although I haven't tried to remove it yet, since the tank is still in the boat.)
Thanks.
Scup,
On here a bit late, but I can tell you what I have learned. I have an aluminum tank and my leak was in the bottom middle area . Based on your post, guess what was the culprit? The Green bonding wire. I will bet you have one.
This caused galvanic corrosion thus your leak. If you look up a galvanic chart, you will see that aluminum is a noble metal. Low stray current thru your bonding wire caused your problem.
I read an article some years ago about two luxury yachts that had the latest in bonding. Both boats at the dock during a lightning strike. Guess what happened?
The bonding wiring allowed the current to run down to the bilge grounding bus, which was also wired to the thru hulls & fuel tanks. When the lightning hit, it blew the fuel tanks up, & instantly vaporized the water in the bilge. This in turn pressured the bilge and blew out most of the thru hulls. This is what damage bonding can do outside of simple stray current.
This is a bigger problem, if in a marina and the surrounding boats are all running a/c's & such. Where do you think all that stray current (which loves salt water) go?
I live in Florida, so I know about galvanic, stray current & bonding. There are proper ways to bond your boat but be careful.
I have disconnected the bond wire from my tank. I cut the connector off the bond wire & used an alligator clip that has a rubber insulating around. When I fuel up, I clip this wire to my tank (diesel). This bonding is to protect against static current that can occur during fueling.
When done fueling, I remove the clip. No bond no problem.
I can tell you more if you want from what has happen to friends, but first hunt down the info & decide for yourself. I can say that I have never had corrosion problems on my C30 since then. Before that, it was also flaking the powder coat off my steering binnacle.
If you can remove the tank & find a mig/tig welder (aluminum), he can repair it pretty easily.
There is a bunch of Coast Guard/Gov't. info on the net that covers this. I have a technical background and spent hours looking at everything.
CR
On here a bit late, but I can tell you what I have learned. I have an aluminum tank and my leak was in the bottom middle area . Based on your post, guess what was the culprit? The Green bonding wire. I will bet you have one.
This caused galvanic corrosion thus your leak. If you look up a galvanic chart, you will see that aluminum is a noble metal. Low stray current thru your bonding wire caused your problem.
I read an article some years ago about two luxury yachts that had the latest in bonding. Both boats at the dock during a lightning strike. Guess what happened?
The bonding wiring allowed the current to run down to the bilge grounding bus, which was also wired to the thru hulls & fuel tanks. When the lightning hit, it blew the fuel tanks up, & instantly vaporized the water in the bilge. This in turn pressured the bilge and blew out most of the thru hulls. This is what damage bonding can do outside of simple stray current.
This is a bigger problem, if in a marina and the surrounding boats are all running a/c's & such. Where do you think all that stray current (which loves salt water) go?
I live in Florida, so I know about galvanic, stray current & bonding. There are proper ways to bond your boat but be careful.
I have disconnected the bond wire from my tank. I cut the connector off the bond wire & used an alligator clip that has a rubber insulating around. When I fuel up, I clip this wire to my tank (diesel). This bonding is to protect against static current that can occur during fueling.
When done fueling, I remove the clip. No bond no problem.
I can tell you more if you want from what has happen to friends, but first hunt down the info & decide for yourself. I can say that I have never had corrosion problems on my C30 since then. Before that, it was also flaking the powder coat off my steering binnacle.
If you can remove the tank & find a mig/tig welder (aluminum), he can repair it pretty easily.
There is a bunch of Coast Guard/Gov't. info on the net that covers this. I have a technical background and spent hours looking at everything.
CR
Interesting! Thanks so much for this analysis!
I didn't even think about this as a potential cause of the problem. And, yes, I do have a green bonding wire. Good to know.
Captnron wrote>>>
On here a bit late, but I can tell you what I have learned. I have an aluminum tank and my leak was in the bottom middle area . Based on your post, guess what was the culprit? The Green bonding wire. I will bet you have one.
This caused galvanic corrosion thus your leak. If you look up a galvanic chart, you will see that aluminum is a noble metal. Low stray current thru your bonding wire caused your problem.
I didn't even think about this as a potential cause of the problem. And, yes, I do have a green bonding wire. Good to know.
Captnron wrote>>>
On here a bit late, but I can tell you what I have learned. I have an aluminum tank and my leak was in the bottom middle area . Based on your post, guess what was the culprit? The Green bonding wire. I will bet you have one.
This caused galvanic corrosion thus your leak. If you look up a galvanic chart, you will see that aluminum is a noble metal. Low stray current thru your bonding wire caused your problem.
It is most likely not the "cause" of your problem. You would have serious other problems if you had a DC leak that bad. Aluminum is also not a "noble" metal it is low on the galvanic scale and thus is an "anodic" metal. In other words it is a weak less noble metal and one that will be anodic to metals "more noble" / cathodic such as copper or copper alloys like brass.
The tanks on boats of this era were cheaply built and thin, usually the bare minimum allowable or .090 wall. They were often improperly installed on wood or foam supports, rubber or other materials that can hold moisture against the tank. They then often had copper dip tubes or copper alloy fittings and if the bonding system goes then the copper, being more cathodic (more noble), can create a hot tank.
Water in the fuel tank, especially an electrolyte like salt water, also creates electrical activity that can eat tanks. Beyond that you have poultice, crevice and pitting corrosion which are all a very common killer of marine tanks. The worst cause of corrosion is wet aluminum and an area deprived of oxygen like under a tank where it sits on foam, wood or another substance that can keep it wet. If this was "electrical" in nature it would not almost always show up in the bottom of the tank.
I have boats I work on that are 40 & 50+ years old with "bonded" aluminum fuel tanks that are original to the boat. The difference is in the installation and the quality of the original tank. Aluminum needs air to keep up its layer of protective aluminum oxide. Starve it for oxygen and get it wet and it won't last long. Install it right, build it right and don't allow water to get into it it and it will likely out last the vessel.
All it takes is for an o-ring leak or not tightening the cap and salt water can get in when you heel or when the salty decks get rained on. There are MANY things that an cause a tank to leak but very low on that list is the bonding wire unless you have a bad stray DC current problem which would manifest in other ways as well....
Mainsail,
You're correct I should have said "anodic" & not "noble". It's been years since I've reviewed the chart.
I do agree with some of your points, but disagree with some others. I mentioned I had other cases for justifying what I posted.
First, my tank sat dry with no salt water problems underneath or from above. When I took my tank to the fab shop, I was told me he had seen this problem alot on aluminum tanks. Funny, as it seemed to show up on the bottoms and in the middle.
Current from the tank top bonding tab travel down all 4 tank sides and attacks the tank bottom from all 4. He believed that was why the leak was usually in the middle. Other times, he told me that if there was a weakness or poor construction it would show up there.
He also noted that the eventual leak point showed an electrical interaction. There was no salt water evidence or corrosion.
I had a friend who had a similar leak as mine, different boat. He had a new custom tank made. He installed the new tank and re-attached the bonding wire. A year later (almost to the day) he came aboard to find his bilge full of fuel. Took the tank out and the leak was in the same area as his original tank. Another tank later I told him NOT to reattach the bonding wire.
That was six years ago. And, guess what, no more leaks. The only attachment was the bonding wire. His tank also sat high & dry.
So, there doesn't have to be one right answer all the time. It was helpful that you added more info for the guys to check and see if any other reasons apply to them. But from what I have seen first hand & learned, I'm sticking to my guns for my particular instance.
CR
You're correct I should have said "anodic" & not "noble". It's been years since I've reviewed the chart.
I do agree with some of your points, but disagree with some others. I mentioned I had other cases for justifying what I posted.
First, my tank sat dry with no salt water problems underneath or from above. When I took my tank to the fab shop, I was told me he had seen this problem alot on aluminum tanks. Funny, as it seemed to show up on the bottoms and in the middle.
Current from the tank top bonding tab travel down all 4 tank sides and attacks the tank bottom from all 4. He believed that was why the leak was usually in the middle. Other times, he told me that if there was a weakness or poor construction it would show up there.
He also noted that the eventual leak point showed an electrical interaction. There was no salt water evidence or corrosion.
I had a friend who had a similar leak as mine, different boat. He had a new custom tank made. He installed the new tank and re-attached the bonding wire. A year later (almost to the day) he came aboard to find his bilge full of fuel. Took the tank out and the leak was in the same area as his original tank. Another tank later I told him NOT to reattach the bonding wire.
That was six years ago. And, guess what, no more leaks. The only attachment was the bonding wire. His tank also sat high & dry.
So, there doesn't have to be one right answer all the time. It was helpful that you added more info for the guys to check and see if any other reasons apply to them. But from what I have seen first hand & learned, I'm sticking to my guns for my particular instance.
CR
Ron,
The issues you describe are caused by electrical leaks and improper wiring not cased by "proper" bonding. A properly bonded boat would minimize the corrosion not accelerate it. Considering that grounding of a tank is part of the Code of Federal Regulations and is federal law, not just some ABYC requirement, advising it be disconnected is not an approach that I would consider a safe one..
From the code of federal regulations:
"Sec. 183.572 Grounding. Each metallic component of the fuel fill system and fuel tank which is in contact with fuel must be statically grounded so that the resistance between the ground and each metallic component of the fuel fill system and fuel tank is less than 100 ohms."
Unbonding a tank is not a solution, it is a band-aid that attempts to circumvent or hide serious wiring issues.
I do come at this from an electrical perspective being an ABYC certified electrical systems specialist and also ABYC trained in marine corrosion. I am not shooting from the hip on this.. Please do not unbond a tank. Find and fix the wiring problem that is energizing the bonding circuit.
Correction
I believe POR 15 is the product not POR 51. I have used it for other areas(iron keel) and so far it is holding up.
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Re: Correction
When we pulled our sixteen year old aluminum fuel tank to install a cleanout port and discovered that the bottom was riddled with internal pinholes, we paid a local welder $200 to cut out the old bottom and weld in a new one. Not the best solution maybe, but we should get another ten to fifteen years out of it, which works out to less than $20 a year.
When we pulled our sixteen year old aluminum fuel tank to install a cleanout port and discovered that the bottom was riddled with internal pinholes, we paid a local welder $200 to cut out the old bottom and weld in a new one. Not the best solution maybe, but we should get another ten to fifteen years out of it, which works out to less than $20 a year.
you are correct. it may be POR 51 for us dyslexics, LOL, but for everyone else it will be recognized as POR 15....
and to prevent it from fouling the fuel pick up.... just leave the fuel pick up on top and the liquid will run out of it and down to the bottom of the tank.... after you have completely coated the inside of the tank by rolling it around, remove the tape from all the ports. but leave the tape covering the damaged areas. it will all drain away and and the air movement will be better for drying....
its a very easy product to work with.
I would not:
1. install a poly tank because they are more dangerous than a metal tank in case of a fire, and ethanol leaches out elements from a poly tank that subsequently clogs the fuel delivery system (BoatU.S. "Seaworthy", April 2012).
2. use a "blind process" like the POR-15 technique to coat the inside of the old tank because the coating might result in loose particles that could clog the fuel delivery system.
Based on personal experience, I would:
1. replace the old tank with a new aluminum tank, which is the safest and best alternative (BoatU.S. "Seaworthy", April 2012).
2. or repair the pinhole in the old tank with Marine-Tex (grey because it's better than the white version). It was a simple and quick repair that stopped a pinhole gasoline (not gasohol) leak in a steel tank for more than five years.
Robert M.
Food for thought
Lots of good info and opinions, as usual folks. I was convinced I would replace my aluminum fuel tank with plastic to avoid future corrosion issues, however I am rethinking that now as I am far more likely to be the victim of mindless government driven fuel changes over the short term and the first tank only lasted 30 years.
I was also planning to go poly for the water tank under the vee berth, but perhaps I will see whether I can have a new bottom welded onto it, if that is where my problem lies. A new aluminum tank will certainly be over $500 given its complex shape. I have a nice 13 gallon flexible tank to hold me over for now.
Lots of good info and opinions, as usual folks. I was convinced I would replace my aluminum fuel tank with plastic to avoid future corrosion issues, however I am rethinking that now as I am far more likely to be the victim of mindless government driven fuel changes over the short term and the first tank only lasted 30 years.
I was also planning to go poly for the water tank under the vee berth, but perhaps I will see whether I can have a new bottom welded onto it, if that is where my problem lies. A new aluminum tank will certainly be over $500 given its complex shape. I have a nice 13 gallon flexible tank to hold me over for now.
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