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>I'd like to spray a fuel-tolerant liner into it. If I can find the product and someone -- or the tools -- to do it. For a liner to work, you'd need to drop th

>I'd like to spray a fuel-tolerant liner into it. If I can find the product and someone -- or the tools -- to do it. For a liner to work, you'd need to drop the tank anyway, as you need to thoroughly clean and strip the inside, then roll the tank around to evenly distribute the liquid liner. At that point, for cars, anyway, you're better off just replacing it. FWIW. For smaller projects, like motorcycles, I have used Red Kote for years, with excellent success. It's the only single-part lining I've tried that holds up. http://damonq.com/red-kote.html http://damonq.com/red-kote.html [edit] This is me cleaning out a rusty motorcycle tank with some chain, solvent, and an old Jeep: https://www.youtube.com/watch?v=GNEwIxWUJjU https://www.youtube.com/watch?v=GNEwIxWUJjU The lining I installed afterwards is still holding up, 5 years later.

pasbesoin 9y ago
Thank you! That Red Kote recommendation looks great for anyone with a smaller and/or more accessible (and/or new?) tank. Hopefully, some other HN readers will get use from it. Note that they have both an internal liner coating and an external one with plastic fibre reinforcement. I wonder whether, if one is installing a new tank, one or both linings are advisable -- stop future problems before they occur. Or whether the lifespans of the liners indicate not applying until they are needed. It won't solve my particular situation, I guess -- that's more a matter of how much I might end up having to replace, in addition to the tank, due to corrosion of the undercarriage. The cost of the tank, I was ready for. But in talking to my mechanic (good guy I've known a long time), he's come to the realization that once he goes after the tank, it's hard to predict how many additional parts would have to be replaced because they'd prove impossible to reinstall in their current condition. The job can be done, but it might exceed what's worth putting into the car versus towards a replacement vehicle. I was hoping to get another year or two out of it, at least, but I had no expectation of making it last forever. (I.e. this is not a restoration or similar.) My problem seems to be just the seam. If I felt I could get a good enough application just right at the seam, I'd pursue that. But that looks to be an ill-advised approach. That's a nice trick, in the YouTube video. I guess it proves, too, there's a way to work duck tape into any repair! ;-)
- Baeocystin 9y ago
  Happy to help! There is no advantage to internally lining a new tank- you would eventually have to strip and reapply even the best liquid liner long before actual internal wear would have been an issue. With so many gas blends using alcohol nowadays, internal rust (in vehicles that are regularly driven) isn't nearly the issue it used to be. Back when gas was just gas, water would collect and pool along the bottom of the tank, leading to rustouts. Nowadays, the alcohols in the fuels will suck up any stray moisture every time you refill. That being said, alcohol/gas blend fuels don't store well, and alcohols will separate out over time, so you can't rely on this effect when thinking about vehicle storage. But for daily drivers, internal rust just isn't an issue any more. The best thing you could do to promote longevity of a car gas tank is to give the exterior a thicker treatment (like the OverKote you mentioned) before installation. Speaking of your particular use case, if you really just want to hack it for one or two more seasons, wire brush the worst of the rust off around the seam, then apply some permatex spray sealer. https://www.permatex.com/products/adhesives-sealants/permatex-spray-sealant-leak-repair/ https://www.permatex.com/products/adhesives-sealants/permate... You will need several coats. It works much better if you do multiple thin ones that you let mostly dry between than if you glob on one or two thick ones. YMMV and all that, but if the seams are only weeping, and not so bad as to actively drip, this would probably do the trick for another year or so. Don't bother with RTV, even ones labeled as fuel/solvent resistant. Silicones in general just don't get along with gas very well, and the sealing properties would fail pretty quickly. I'm glad you enjoyed that video. I was more proud of it that I really should be, and making actual use of duct tape was a part of it. :D
  - pasbesoin 9y ago
    Thanks again! I'll have the mechanic hoist it again and have a good look. For liability if nothing else, I'll probably have to find a lift I can borrow and do the job myself, but first I'll make sure the entire exterior of the seam is accessible while the tank is in place. I never saw a drop (re drips) until just a month or two ago -- when I parked for a day over some fresh snow. So, it may be too late, now, but it's worth a shot. I also can put 8 gallons into an empty tank without the problem manifesting. If I can somewhat seal and protect the seam from the exterior, per your suggestion, I can also stick to partially filling the tank, most of the time. The car only has about 135K on it, and the interior is pretty much spotless while the exterior has had only a couple of nascent rust spots that I've actively kept under control. Until this winter; I had to switch detailers and the new one seemed to create paint chips rather than mitigating them. I used to do most of this work myself, but health has had me seeking help. Anyway, it really seems worth getting the extra year or two out of it, if I can. As for the alcohol blend fuels, I was aware that they help significantly in keeping the tank "dry". It's been my understanding that they may also contribute to the lower instances of "vapor lock" that we see, these days. At least, at my mild altitude and (mostly) non-extreme environment. Applying an exterior coat does sound like an interesting idea. One concern I would have, is whether if and as it deteriorated, it might trap moisture and corrosives next to the tank, turning from protectant to trap and accelerant. I used to rinse my undercarriage extensively each spring, after the last of the salt was washed off the roads by rain. The last some years -- again, health -- I've gotten... well, I guess I could be self-deprecating and call it lazy. That may have made things worse, but 18 years of Chicagoland winters doubtless bear the bulk of the responsibility, regardless of such mitigation efforts. And I didn't have this car for the first 10 or so years of its life; the damage was already well underway.

pasbesoin 9y ago

Thank you! That Red Kote recommendation looks great for anyone with a smaller and/or more accessible (and/or new?) tank. Hopefully, some other HN readers will get use from it. Note that they have both an internal liner coating and an external one with plastic fibre reinforcement. I wonder whether, if one is installing a new tank, one or both linings are advisable -- stop future problems before they occur. Or whether the lifespans of the liners indicate not applying until they are needed. It won't solve my particular situation, I guess -- that's more a matter of how much I might end up having to replace, in addition to the tank, due to corrosion of the undercarriage. The cost of the tank, I was ready for. But in talking to my mechanic (good guy I've known a long time), he's come to the realization that once he goes after the tank, it's hard to predict how many additional parts would have to be replaced because they'd prove impossible to reinstall in their current condition. The job can be done, but it might exceed what's worth putting into the car versus towards a replacement vehicle. I was hoping to get another year or two out of it, at least, but I had no expectation of making it last forever. (I.e. this is not a restoration or similar.) My problem seems to be just the seam. If I felt I could get a good enough application just right at the seam, I'd pursue that. But that looks to be an ill-advised approach. That's a nice trick, in the YouTube video. I guess it proves, too, there's a way to work duck tape into any repair! ;-)

Baeocystin 9y ago
Happy to help! There is no advantage to internally lining a new tank- you would eventually have to strip and reapply even the best liquid liner long before actual internal wear would have been an issue. With so many gas blends using alcohol nowadays, internal rust (in vehicles that are regularly driven) isn't nearly the issue it used to be. Back when gas was just gas, water would collect and pool along the bottom of the tank, leading to rustouts. Nowadays, the alcohols in the fuels will suck up any stray moisture every time you refill. That being said, alcohol/gas blend fuels don't store well, and alcohols will separate out over time, so you can't rely on this effect when thinking about vehicle storage. But for daily drivers, internal rust just isn't an issue any more. The best thing you could do to promote longevity of a car gas tank is to give the exterior a thicker treatment (like the OverKote you mentioned) before installation. Speaking of your particular use case, if you really just want to hack it for one or two more seasons, wire brush the worst of the rust off around the seam, then apply some permatex spray sealer. https://www.permatex.com/products/adhesives-sealants/permatex-spray-sealant-leak-repair/ https://www.permatex.com/products/adhesives-sealants/permate... You will need several coats. It works much better if you do multiple thin ones that you let mostly dry between than if you glob on one or two thick ones. YMMV and all that, but if the seams are only weeping, and not so bad as to actively drip, this would probably do the trick for another year or so. Don't bother with RTV, even ones labeled as fuel/solvent resistant. Silicones in general just don't get along with gas very well, and the sealing properties would fail pretty quickly. I'm glad you enjoyed that video. I was more proud of it that I really should be, and making actual use of duct tape was a part of it. :D
- pasbesoin 9y ago
  Thanks again! I'll have the mechanic hoist it again and have a good look. For liability if nothing else, I'll probably have to find a lift I can borrow and do the job myself, but first I'll make sure the entire exterior of the seam is accessible while the tank is in place. I never saw a drop (re drips) until just a month or two ago -- when I parked for a day over some fresh snow. So, it may be too late, now, but it's worth a shot. I also can put 8 gallons into an empty tank without the problem manifesting. If I can somewhat seal and protect the seam from the exterior, per your suggestion, I can also stick to partially filling the tank, most of the time. The car only has about 135K on it, and the interior is pretty much spotless while the exterior has had only a couple of nascent rust spots that I've actively kept under control. Until this winter; I had to switch detailers and the new one seemed to create paint chips rather than mitigating them. I used to do most of this work myself, but health has had me seeking help. Anyway, it really seems worth getting the extra year or two out of it, if I can. As for the alcohol blend fuels, I was aware that they help significantly in keeping the tank "dry". It's been my understanding that they may also contribute to the lower instances of "vapor lock" that we see, these days. At least, at my mild altitude and (mostly) non-extreme environment. Applying an exterior coat does sound like an interesting idea. One concern I would have, is whether if and as it deteriorated, it might trap moisture and corrosives next to the tank, turning from protectant to trap and accelerant. I used to rinse my undercarriage extensively each spring, after the last of the salt was washed off the roads by rain. The last some years -- again, health -- I've gotten... well, I guess I could be self-deprecating and call it lazy. That may have made things worse, but 18 years of Chicagoland winters doubtless bear the bulk of the responsibility, regardless of such mitigation efforts. And I didn't have this car for the first 10 or so years of its life; the damage was already well underway.