Topic: Leaking gas tank - Front wheel bearings

[ev0lve]

Seems my tank is leaking. It took a 3 foot header into the floor and now appears to have a slow leak although I can't identify exactly where yet. So 2 questions on the tank

There are some patches that look like bubble-gum on the bottom of the tank that I assume are JBWeld. Is that common and how do you get pinhole punctures on the bottom of the tank?

I think the leak is probably coming from a seam but I'll put the foot powder to it to make sure. Once I know where the leak is what's the best way to fix it? If the answer is weld what's the second best way? I'm wondering if there's a way to apply some solder to plug up any leaks but all options are good to know.

On the wheel bearings, take a look at the attached pic. It looks to me like that's grease getting thrown out of there by centrifugal force. Given that the bike is 33 years old is that normal? Bearings? Someone used to light a grease and it's migrating?

Thanks!
Iggy

[Johnie]

Looks like someone tried to put some grease in the hub there.  To be safe I pulled all the bearings out of my KO and replaced with sealed pre-packed bearings. 

Regarding the tank, maybe it sat empty a while with the previous owner and rusted.  You could take it to a radiator shop and have them fix it.  The seams are a likely spot for them to leak too. 

[ev0lve]

Nice. I happen to have the front bearings. So nothing to worry about for the most part?

The inside of the tank appears rust free but it had sat for ten years prior to my buying it. Hadn't thought of a radiator repair shop. What process do they use (Weld? Solder?) I'd like to do it myself if I can.

[Johnie]

Ask some of your biker friends in the area of a good shop that works with the bikers.  I have one here that is well known for this type of repair and will also seal the tank for a total of $100.  I am not sure if they solder or weld that tank seam maybe some else knows.

[ev0lve]

The more I get into this bike the more it's become a vendetta to do all the work I can myself. Started off just being a top end rebuild and now I'm lacing and trueing my own rims

A glutton for punishment it seems.

So poking around it looks like the gum on the bottom of the tank is Permatex


Since one of the five gobs came up with a fingernail I'm thinking that's not quite so permanent. Can't find any reference to this particular Permatex product here on the boards either which probably means it sucks long term or it's just too crazy to use for this application (I'm assuming of course).

For the solder I was able to make Google dig up one lone reference from somebody talking about rotary lawn mowers who said, "I have gotten lucky and have been able to solder repair leaks in small engine tanks using my 140 watt soldering gun after leaving the tank to preheat in the sun all afternoon while I was at work. You have to be patient to do so..."

And that doesn't sound promising. I did some HVAC work as a kid soldering copper tubing together with a propane torch. Same kind of process (I assume)?

Would really appreciate some specifics if anyone has them.

Thanks!

[troppo]

G`day iggy
You can easily silver solder the holes or even braze them if you know what your doing.
The tanks will rust on the bottom because fuel will float on water, so if theres any water in your tank it will all settle to the bottom........
If your going to solder or braze the holes, make sure you clean the tank thoroughly and them purge it to make sure theres no fumes left.
A few fumes make for one hell of a big (and dangerous) bang.
Purge the tank with car (or bike) exhaust, the fumes will be flushed out by the flow of gas and the hot exhaust will help dry any residue left in there.
Cheers mate
Troppo

[ev0lve]

Thanks Troppo! I guess I'll pick all the Permatex off of it and try not to splode myself fixing it 

[KingCustomCycles.com]

No mention of Kreem tank sealer?  What gives? The tank may look clean but has pinhole rusted along the bottom seam from the inside as stated above.  I have used muriatic acid or toilet bowl cleaner to remove the rust in cases like that and then sealed with NAPA tank sealer or Kreem.  I have had mixed results.  I have had 2 tanks bubble the new paint along the seam after 30 days.  It is a real gamble.  I use rust free tanks now exclusively and deal with the dents and scrapes. 
If it has holes, regular rosin core, lead based, solder can be used to close them with a propane torch and some good cleaning prep.  THE FUMES MAY EXPLODE! so clean the inside of the tank with soap and water repeatedly and then fill it most of the way with water during the work.  If water touches the back of your solder area it won't heat up so you will have to have a small air/fume pocket.  The last tank I soldered had fiberglass mat over pole barn screws filling several dent pull holes.  Creative, but ultimately leaky. 

[troppo]

No mention of Kreem tank sealer?  What gives? The tank may look clean but has pinhole rusted along the bottom seam from the inside as stated above.  I have used muriatic acid or toilet bowl cleaner to remove the rust in cases like that and then sealed with NAPA tank sealer or Kreem.  I have had mixed results.  I have had 2 tanks bubble the new paint along the seam after 30 days.  It is a real gamble.  I use rust free tanks now exclusively and deal with the dents and scrapes. 
If it has holes, regular rosin core, lead based, solder can be used to close them with a propane torch and some good cleaning prep.  THE FUMES MAY EXPLODE! so clean the inside of the tank with soap and water repeatedly and then fill it most of the way with water during the work.  If water touches the back of your solder area it won't heat up so you will have to have a small air/fume pocket.  The last tank I soldered had fiberglass mat over pole barn screws filling several dent pull holes.  Creative, but ultimately leaky. 

I know the tank sealers are all the rage in the states, and available everywhere.
Here in Australia they are only available in highly specialised import shops as far as i know.
Anyway, why put a bandaid on  it when you can fix it properly?

[KingCustomCycles.com]

And what is proper oldfart?  50K customs use Kreem when all the welding and stretching is finished.  Proper for me is a lasting repair that is cost effective.  I prefer soldering or replacing the tank but have had success with sealers.

[Soos]

In the past I have attempted to braze a tank... with poor results.
Not something to find out after painting the tank before having put gas back in it.
I thought it was good.... until I saw the paint bubbling and smelled a LOT of gas.


But I am only recently learning how to weld properly.
If I were to have that project to do again, I would flush the tank with argon or Co2 from exhaust and tig weld if possible.

I'm sure any good radiator shop would be able to fix it properly.
My father in-law had a tank modified to fit the filler spout to match his '65 ford ranchero lately.
Cost him 60.00 for tank cleaning, and weld time.
I still think he should have paid the extra 40.00 to have it redkote lined.


l8r

[troppo]

And what is proper oldfart?  50K customs use Kreem when all the welding and stretching is finished.  Proper for me is a lasting repair that is cost effective.  I prefer soldering or replacing the tank but have had success with sealers.

Its just my opinion, no offense intended mate.
I always prefer a good mechanical bond/repair than a chemical bond/repair, as i mentioned the tank sealers are not readily or cheaply available here so brazing or soldering is the best method to use, there are dye checks readily available that will show a hole smaller than a human hair within about 2 minutes after application of the spray. do this before you do anything after brazing or soldering and you will know if you have any leaks whatsoever.
Just my two bobs worth