Vintage Honda unit, I think it started leaking after paint and its clearly had repair attempts.
|
|
|
Weld or seal gas tank?
- Thread starter eng2007
- Start date
looks like rust running out of one hole. how bad is the inside? the late Ross Thompson said he hooked his shop vac in reverse and blew air through it for about 20 minutes before welding with no explosions reported.
last time I mentioned this some bright soul suggested a spark could travel out my hose and ignite the tank. so maybe don't do this if your vacuum is a POS.
last time I mentioned this some bright soul suggested a spark could travel out my hose and ignite the tank. so maybe don't do this if your vacuum is a POS.
Mad Mike
Well-known member
I’ve redone lots of old tanks, it’s easy but lots of work and there are few shortcuts.Vintage Honda unit, I think it started leaking after paint and its clearly had repair attempts.
here’s how I do tanks.
1. strip to bare metal using chemical stripper, media blasting or 80 grit sanding.
2. remove inside and outside rust using electrolysis or Evaporust. Getting the inside clean can be hard, dump a box of small screws or nuts into the tank and shake like hell for 30 minutes.
4. Treat any residual and invisible rust with a wash of phosphoric acid, inside and out. If that’s hard to find, you can use liquid or spray rust converter juice from Canadian tire.
5. plug petcock holes and fill tank with water, look for leaks.
6. Lead pinholes, seam leaks and thinned areas. Watch Eastwood YouTube videos to learn about leading sheet metal surfaces. Go back to step 5 to check leaks.
7. spray inside of tank with wd40, protects it till it’s filled with gas.
8. Fair, prime and install. I like to run for a few days in primer before applying the finish paint. Saves effort if you missed a leak.
if it’s a quick and dirty, use a POR kit, cheese up the up the rusty area outside and paint. Good for a few years.
At first I thought you missed the paint - instead you're genius. I would go full blown and find gas messing up my new paint.
Also I have heard chain works good and is easier to get out. Havn't tried it though.
Mad Mike
Well-known member
Chain, or threading a string thru washers or nuts makes them easier to remove.
I got lazy and used a handful of 2” drywall screws on the last tank I did, took me an hour to shake them out.
Thanks folks for the input but Im looking to use this tank (and have it last) without worrying about the aesthetics too much. as you can see the tank already been painted and it looks good so this area with the leaks I would just blend instead of redoing the whole tank.
let me ask more precise questions:
1. can the holes be sealed by a good welder and the tank then used without any sealer.
2. can I not repair the holes and just clean and seal the inside
3. should I do both and if so, why
I would not use POR15 or similar goop, I would use Caswell's 2 part epoxy as I have done on others.
let me ask more precise questions:
1. can the holes be sealed by a good welder and the tank then used without any sealer.
2. can I not repair the holes and just clean and seal the inside
3. should I do both and if so, why
I would not use POR15 or similar goop, I would use Caswell's 2 part epoxy as I have done on others.
I restore my own tanks and I’ve found if there are pin holes it’s hard to weld as the metal around them is so thin you just end up chasing the hole. It’s probably better to have them brazed or soldered.
The best way is just to cut the rotten piece out and put in new metal. It’s faster and cheaper in the long run and you won’t need a sealer. I run argon in the tank behind the weld as there is less chance of the back of the weld being crusty and porous than if exposed to air during the process. That should also prevent ignition of residual fumes.
I think it’s also hard to find a commercial shop that will work on gas tanks because of liability issues
The best way is just to cut the rotten piece out and put in new metal. It’s faster and cheaper in the long run and you won’t need a sealer. I run argon in the tank behind the weld as there is less chance of the back of the weld being crusty and porous than if exposed to air during the process. That should also prevent ignition of residual fumes.
I think it’s also hard to find a commercial shop that will work on gas tanks because of liability issues
+1 on chasing the holes.
I'm guessing the tank is a formed metal top to which a lower pan has been welded. If that is the case there is likely a seam that would have held water since water is denser than gas.
This causes lean oxygen corrosion. Lean oxygen corrosion tends to create pits rather than sheet / surface rust and who knows how many of these pits are just waiting for a new coat of paint to come along.
It's a comparison of a new tank to the cost of re-doing the job over again. Is an actual new tank (Not new to you) available and / or are the used ones likely to be the same as the one you have?
I'm guessing a new old stock tank is priced like Toronto real estate and a total rebuild to factory specs about the same. A liner coat every few years or until a BNIB falls at your feet, would be reasonable.
Thanks for the input, I've ordered some of the Caswell and will clean and seal.
In terms of methods for cleaning the inside (its not that bad, some rust spots here and there, no previous liner), is there a real difference between vinegar and muriatic acid? I need to save the outside paint so cant go into electrolysis, etc.
Has anyone tried phosphoric acid-based rust converters like Rust Mort in their tanks then sealing over that? I used some on the inside walls of a vintage chrome rim and it seemed to actually work well after some trial and error.
Side question:
I have a spare tank but its way beat up. Since the Caswell comes by the pint I have enough to seal both tanks. The issue is that it has a previous lining of POR15 in there that has cracked all over the bad rust underneath is flaking out. After some research and testing, I found that Acetone greatly expands the liner (like by a factor 5 to 10) after maybe an hour of immersing a test sample. I suppose I would soften the liner by sloshing the Acetone in there for an hour then shake a chain around to dislodge it? Anyone done this before?
In terms of methods for cleaning the inside (its not that bad, some rust spots here and there, no previous liner), is there a real difference between vinegar and muriatic acid? I need to save the outside paint so cant go into electrolysis, etc.
Has anyone tried phosphoric acid-based rust converters like Rust Mort in their tanks then sealing over that? I used some on the inside walls of a vintage chrome rim and it seemed to actually work well after some trial and error.
Side question:
I have a spare tank but its way beat up. Since the Caswell comes by the pint I have enough to seal both tanks. The issue is that it has a previous lining of POR15 in there that has cracked all over the bad rust underneath is flaking out. After some research and testing, I found that Acetone greatly expands the liner (like by a factor 5 to 10) after maybe an hour of immersing a test sample. I suppose I would soften the liner by sloshing the Acetone in there for an hour then shake a chain around to dislodge it? Anyone done this before?
I have been using this lately based on recommendations from UK Motorcycle Forums.
bilthamber.com
Its really good, and for a tank with no holes it will bring it up like new.
It is paint safe, non-hazardous, biodegradable and can be shipped worldwide but I have not been able to find a source for it in North America. If you try to buy directly from them the cost of shipping is completely mental so I bought 2x1kg tubs from Amazon
EDIT: Sorry, typo. It was EBAY
Deox-C - Bilt Hamber
Crystalline non-toxic rust remover that produces a powerful corrosion removal bath.
bilthamber.com
Its really good, and for a tank with no holes it will bring it up like new.
It is paint safe, non-hazardous, biodegradable and can be shipped worldwide but I have not been able to find a source for it in North America. If you try to buy directly from them the cost of shipping is completely mental so I bought 2x1kg tubs from Amazon
EDIT: Sorry, typo. It was EBAY
Last edited:
Mad Mike
Well-known member
All rust removers/converters will likely create paint issues. They won't necessarily strip paint, but they do get through paint and convert trapped iron oxide which generally lifts paint in small bubbles over time. I wouldn't use Evaporust, CeoxC and electrolysis unless I planned to repaint.I have been using this lately based on recommendations from UK Motorcycle Forums.
Deox-C - Bilt Hamber
Crystalline non-toxic rust remover that produces a powerful corrosion removal bath.
Its really good, and for a tank with no holes it will bring it up like new.
It is paint safe, non-hazardous, biodegradable and can be shipped worldwide but I have not been able to find a source for it in North America. If you try to buy directly from them the cost of shipping is completely mental so I bought 2x1kg tubs from Amazon
EDIT: Sorry, typo. It was EBAY
I did a 72 CB350 tank about 2 years ago with it and its been fine. Absolutely no issues and i even spilled it over the outside of the tank.
I've used POR-15 metal prep and I've had issues like that with rotten metal that is full of pinholes.
Its almost like the rust is plugging the pinholes and the solution removed it and opened them up... but in cases like that paint is the least of your problems... LOL... thats why I mentioned a solid tank (original or repaired) with no holes above.
Mad Mike
Well-known member
I always strip paint, solder pinholes then lead over so it's not going to be a problem for me. Just would be a shame for someone to try to preserve paint by going inside a tank with Evaporust only to find the outer paint blister off a month later.
|
|
|
|
|