fuel tank holes

[el__burro]

hello,
i am about to complete my cb750 project.
unfortunately while i am washing the tank to seal it, I've notice a few tiny holes.
sure there are more as i sand off the paint.
my question is, how do i close them?

regards
el__burro

 

[1fasgsxr]

get someone to weld them...the sealer may fill them..

 

[el__burro]

The filler option is my favourite choice.
Any?
Thanks
El__burro

 

[carnivorous chicken]

Maybe my eyes are bad, but I don't see any holes unless they are the two big dark spots. If that's them, too big for a sealer to fill. If it's not them, can you repost the photo with the holes circled? Both POR15 and Redkote will seal up small pinhole leaks. Avoid Kreem.

 

[el__burro]

actually the holes are the 2 black spots.
I've used por15 before but with no holes.
any other suggestions?

thanks
el__burro

 

[iatethepeach]

If you're going to seal the tank, activated JB Weld after careful preparation may be worth a shot. Welding it for real would be a sure thing, though.

 

[el__burro]

Thanks,
I've used por15 for sealing the tank in the past. Worth it.
I have decided to go weld.
I have a mig welder though.
Is that any good?

The picture below after a 5 minutes sanding.

Thanks
El__burro

 

[Brodie]

I just went through a similar thing with a tank on one of my bikes.

What was a small pin hole ended up blowing out to a massive hole. My mates tried TIG, after that did not work they tried OXY and that just burnt away the rest.
Judging by those holes, is your time and the risk of further holes developing really worth the price of a new tank?

I decided against continuing with my crap tank.

 

[trek97]

My tank was full of holes. I took it to a local radiator shop. They soldered them shut. Its not pretty, but its solid. In the end had a weeping leak. So I used POR-15. Now its holding gas.

http://www.dotheton.com/forum/index.php?topic=65898.msg756856#msg756856

 

[AgentX]

crap tank

You keep it in your tank? That can't be good for the carbs.

Normally I just flush mine...

 

[Kamn]

those can be easily soldered shut, then seal the tank

 

[Brodie]

You keep it in your tank? That can't be good for the carbs.

Normally I just flush mine...

Well, you know, I never thought of that.

Would save a lot of time every week cleaning sh!t out of the carbs.

 

[Ichiban Moto]

I need to do a "how to" video on this topic.

If anyone has a swiss cheese crap tank- send it to me !

 

[jpmobius]

Soldering is good because it will add a little structure. Very hard to seal it with just solder because there are likely so many holes waiting to happen and not visible. Your tank probably sat for a long time half full of gas. Moisture collects in the tank and heads to the bottom under the fuel and rusts the whole bottom of the tank. Especially bad with new alcohol gas that absorbs a lot of water. If you clean the rust out completely with acid you very likely will see a LOT more holes. Those are the holes you will miss trying to just solder up what you can see now. That's why welding will likely just vaporize a lot of the bottom and why sealing with something like POR-15 is needed in addition. Soldering works really well, but you have to hit all the holes! I've had a few tanks like this - very fragile on the bottom and potentially can be a real problem to make reliable because the actual damage can be a lot worse than it looks like. I've seen tanks that had a straight horizontal line of holes along the side near the bottom indicating the water line! You can fix it, but if you can just cut your losses and get a good condition tank you will probably be better off - really disappointing having the paint ruined from a missed hole somewhere. If you do fix it, and especially if you use acid which will absolutely positively remove 100% of the rust, make sure you are extra thorough neutralizing the acid, as the slightest discrepancy will ruin your paint down the road. Soldering flux has acid, and just grinding and sanding it will not do - residual acid HAS to be chemically neutralized or two months later you will see it bubble under your paint!

 

[AgentX]

I imagine cutting out the thin sections, then welding in a new piece of sheet metal, is rarely cost-effective unless minimal shaping work is involved. Good assumption or no?

On another note, I saw a Punjabi guy stop a friend's tank which was leaking along an inch-long crack that developed on a friend's bike, using lye soap, jute-fiber string, water, and a flat rock. He cut the string up into short frayed bits, mashed it into the soap with a little water on the rock, and kneaded the mixture till it looked like a big pink booger. Applied to the tank, and it sealed and held. (Apparently the soap reacts with the gas...?) One of two times I was impressed by ad-hoc repair skill in India. (Second time was several days later when he bent friend's pipe back into place with a long, stout stick which miraculously came to be his hand, in the desert at the very site of our minor crash...)

Held like a champ through a week of rough riding in Rajasthan, and seemed poised to stay in place forever, at least until the rainy season...

 

[trek97]

Soldering flux has acid, and just grinding and sanding it will not do - residual acid HAS to be chemically neutralized or two months later you will see it bubble under your paint!

Thats what Im crossing fingers dont happen. Im hoping I got it...but I didnt wash it w baking soda. Probably should have.

After browning rifle barrels I have to wash them in baking soda to stop the rusting action of the barrel brown. Wishing that had dawned on me at the time. :

 

[whynot]

My tank was full of holes. I took it to a local radiator shop. They soldered them shut. Its not pretty, but its solid. In the end had a weeping leak. So I used POR-15. Now its holding gas.

http://www.dotheton.com/forum/index.php?topic=65898.msg756856#msg756856

Trek, I may have to send you my tank to get repaired.....seem no one here that wants to touch my tank.

We'll see.....................!!!!!!!