Topic: Rust Holes in Gas Tank

[alfego]

Prepping the '74's gas tank for coating, and thought I'd dremel wire brush the rust spots on the bottom, opposite side of petcock, and whattaya know, they pushed right thru.  I don't weld, so I'm ignorant, can any brazing or welding be done to repair the area infected with rust disease?  Or is there another way?  First time I've run across rust holes in a gas tank.  I'd take a pic, but loaned out the camera.  The area infected is the recessed area where gas/water would definitely collect and cause this. 
Alfego

[Lostboy Steve]

It depends on how far the rust goes how thin is the surrounding area? It can most likely be done or you'll have to weld in some sheet metal overlapping the #$%*ed section by about a 1/2 inch. Then coat.

[KingCustomCycles.com]

You can continue cleaning, place tape on the outside of the tank, then seal with Kreem, or por15 type sealer.  If they aren't too big (pinholes), the sealer will fill them and provide a permanent fix.  You may need to slosh, allow to dry, and slosh again to get the thickness needed to seal holes.

[Danno]

well the best way to proceed would be a different tank but if you need to fix this one for lack of funds or lack of availability then

clean off the paint in the affected area don't worry too much about the rust right now kind of need it for the moment
go buy one of those fiberglass repair kits from the auto parts store the one with the woven cloth not the chopped string
follow the directions on the box put a strip down big enough to cover the rusted area and lip up onto the bottom flange make sure it is flat to the metal and it does not need lots of resin so spread it out well make sure it is flat and no bubbles
then do the same thing again only make the piece of fiberglass cloth about an inch bigger than the other one
finally do one last piece over the top of all the others i like to go bigger still but as long as it is at least the same size as the last one then it will work now take your dremel when it is set up good but not quite fully hard and trim the excess off of the bottom flange just needs to be flush to the flange so it does not hang down
let it sit over night
get some rust resolver from harbor freight or where ever and put 2 gallons in the tank let it sit over night make sure the petcock is closed

next put a piece of plastic over the filler neck and close the cap this is assuming you have the flip top cap the point is you have to seal the vent somehow
now turn the tank over upside down you will have to use blocks to keep it flat like it was when sitting right side up
let it sit over night you may need to do this for 2 nights each side if your tank is severe
once all the rust is gone then drain the rust resolver back into  its bottles and keep it for other rusty parts you want to get rust off like rims bolts etc...
get all the rust resolver out then rinse with alcohol and leave the cap off to dry as soon as it is dry look for any more holes fix them the same way you did before but i am betting you wont find any
if there is no more repair and the tank is dry from the alcohol then fill it with fuel immediately you no longer have a need for the kreem or whatever you were going to do so take it back where you got it to help pay for the rust resolver
if you dont fill the tank right away you can get flash rust if this happens just rinse it again with rust resolver 20 minutes a side and rinse it out with alcohol right after you are done then fill it with fuel i just did this to my 74 and I am glad i did it this way as the coatings over time and exposure to fuel can break down and come off causing a worse problem than the rust

[alfego]

Thanks for the replies.  All good suggestions.  Since I have the time and would like to repair this tank, I'm gonna do it.  I do have access to another tank, so if this doesn't work, I will go that route.  Good ideas and thanks again.
Alfego

[Lostboy Steve]

Its really not a big deal to cut out the area and weld in a little filler metal. Just take it to a muffler shop, I'm sure someone there will be able to help just try to find someone with a pulse. A lot of muffler shops will only do things that they are "programmed" to do.

[Trav-i]

If it's only a few small pin holes I would get them brazed by a good shop.  Then coat the inside of the tank.  I have the same problem on my F tank, plus it was very nasty on the inside.  After I cut my tank a part and blasted it several small holes showed up.  So my brother in law is going to braze them, then weld the tank back together.  After that I'm gonna Red Kote it for good measure.

[alfego]

Just took the gas tank to one of my fellow riding buddies, he's a welder at Alstom, boiler builder.  Anyways, I'll have it back this weekend I hope.  He says it won't be too hard, except on my wallet  .  He's got a great '69 CB350. 
Alfego