Welding a gas tank

[corax]

That title got your attention didn't it?

Dammit! Last week I finished the install on my Aux Tank (http://www.ultimateyota.com/index.php?option=com_smf&Itemid=26&topic=4256.msg73729#msg73729) and got the transfer pump all wired up. So I filled it with gas and flipped the switch to make sure everything worked alright, still leaving some in just because - fast forward one week, I get home from a business trip and smell gas

http://i280.photobucket.com/albums/kk171/batardsalamano/aux%20tank/100_4396.jpg

it's a slow leak, probably just a pinhole, behind the mounting bracket - I can see a few slow bubbles of gas from where the bracket meets the tank. Before I installed it I took a good look inside and everything looked clean and rust free - the only rust at all was where the bracket welds were (heat cooked off galvanizing/coating). Since I can't afford closing on the property we just got and buying a new NWMP tank ($630 + shipping), I'm thinking I should be able to weld all the way around the mounting bracket - effectively sealing the leak . . . hold on now, I'm not talking about just running a bead straight to the tank and blowing myself up. The way I've heard to go about this is: drain the tank, rinse with ammonia, let it air out a bit (blow air into it with a shop vac), completely fill with water and then go to town and run a fat bead of weld to it.

-or- I could try to undercut the area between the gap in the welds, clean it and JBWeld it. My only issue with this is that I'm unsure of how long that will hold since gas tanks usually build a bit of pressure in the hot sun.

Any other suggestions or am I just being cheap? Honestly, if I can't fix it, it'll probably end up scrap metal :(

[X-Tool Pimp]

empty the fuel, fill it with water and weld it up........

[Nick]

JBweld first and see if that works for you. Less trouble and JBweld is VERY strong. One of the wheels on my truck had three pinhole cracks and was letting out air VERY slowly. I JBwelded it about two years ago now and I never loose pressure and I run at 45psi.

[Good Times]

jbweld should work but I'd say if you have the time, I'd fill the tank with water and go to town on the cracked area.

[YotaFun]

I voted to drain the fuel, Fill with water and go to town.

Heck any gas you take out of it you can put right into your other vehicles so your not loosing $$$ in gas.

[CJM]

Water and weld. They also make a gas tank repair putty they sell at the parts store-might wanna give that shot.

[4runnerchevy]

Gas tank puddy works well, I used it once in an emergency (leaf spring through tank thing). I used that same tank for 12 years before I recently went to fuel cell. If I were to weld it I would fill it with water, or just rinse would be fine, open all the holes (filler, ports, etc). Clean, then warm the area with a propane torch, stand back (just in case of flash). Weld it. I have never even had a flash with this method. We used to purge with argon, but not anymore.

[04 Rocko Taco]

Jb weld worries me because even a slow exposure to gas will eventually soften that JB weld, I say fill the tank with water, and go to it.

[corax]

Jb weld worries me because even a slow exposure to gas will eventually soften that JB weld


That I did not know . . . . good info, thanks :thumbup:

[CJM]

^ I found this out the hard way when I tried to repair a plastic weed whacker gas tank with it. Cleaned it up real nice and in 3 weeks the epoxy fell off..

For a temp fix I think you should use the fuel tank repair putty. Then when you have more time, drop the tank and weld.

[corax]

For a temp fix I think you should use the fuel tank repair putty. Then when you have more time, drop the tank and weld.


I think this might be the way to go for now - hopefully I can get the tank putty to seal everything up

Thanks for the replies guys :D

[Small_words]

Keith, have you thought about this or something like it?

http://www.kbs-coatings.com/Tank-Sealers_c_7-1-0.html

[corax]

Keith, have you thought about this or something like it?

http://www.kbs-coatings.com/Tank-Sealers_c_7-1-0.html


Thanks for the link :thumbup:

I think if the tank putty works (even if it doesn't) I may give that a whirl a little bit down the road when I have some time again.

[corax]

Damn, I'm a lazy a$$. I didn't even realize it's been this long and I still haven't gotten this taken care of. Next weekend! Or maybe when the weather gets a bit cooler. Well, soon anyway.

I sent NWMP an email a few weeks back explaining what was going on (and to ask if I could get a discount on a new one even though this one is 20 yrs old). They suggested I try a radiator repair shop and said I could buy a tank without the install kit for ~$100 less than the regular retail price. Their tank guy didn't have any experience with the liner kits I linked above, so he didn't have any advice on which might be better.

I previously tried the JB Weld type gas tank putty which helped but didn't stop it from seeping gas completely - I never really had a drip, just a strong odor and a wet spot trickling down to my spare tire.

So I recently bought the Bill Hirsch tank sealer kit: www.hirschauto.com/prodinfo.asp (http://www.hirschauto.com/prodinfo.asp). I didn't read one bad review in any of my research about these products and it's supposedly the same type of sealer used in aircraft tanks, it that means anything. I went with this product partially because you can save any leftover product to put in a second coat if you want. Also, I saw plenty of restoration companies using this one. A side benefit is that it happened to be the cheapest at only $46 - now to get it done.

I've read about instances where the POR and KBS Coatings separate from the metal, in effect creating a floating bladder within the tank. This may have been user error in the prep stage, but it seemed like a common possibility among most urethane based coatings with bits breaking off here and there and later clogging fuel filters. I read a whole bunch about a product called Kreem, feedback was split between being neutral or very negative. The main problem with Kreem seems to be that if you mess up the prep stage and it starts to come away from the metal you're only recourse to remove it is to burn it out. KBS and POR can be removed with muriatic acid.

All the products basically follow a 3 step process with thorough dry times in between:
1) some form of cleaner, often muriatic acid, to get the varnish out
2) some nasty chemical to rid the tank of rust and etch the metal in preparation for the sealer
3) the sealer itself, followed by a few days of dry time before re-installation

. . . when I get it done I'll update the thread with my thoughts & impressions on the product and process

[04 Rocko Taco]

so that'll be in 2013 Keith? :hillbill:
You know i'm just giving you a hard time. I'm the worlds worst project procrastinator.
Let us know how it goes for you!

[corax]

Normally I'd say "yeah, probably" but I have a medium size road trip coming up and 4 projects taking up all the space in the back of the truck so I guess I need to finish something up

[Crinale]

i say try to weld it.. if something goes wrong u could always pick up a replacement tank after

[04 Rocko Taco]

Well definitely let us know how it goes, if it were me, I think I would still fill it up with water and weld it... but let us know how it goes for sure. As much abuse as tanks take off road it'll be handy info to have.

[Crinale]

As much abuse as tanks take off road it'll be handy info to have.

i guarantee a welded tank would handle more abuse than the current JB Weld :P

[corax]

I started the process today by pulling the tank out of the 4runner. I'm REALLY surprised how clean it is on the inside, I was expecting a lot more varnish in this 20 year old tank. You can see the rust spot which is the source of my pinhole leak - I had thought I'd find rust where the welds are (burned off zinc coating) but that's not the case. You can also see the little bit of varnish that is inside the tank just below the welds and extending to the right.

http://i280.photobucket.com/albums/kk171/batardsalamano/100_46501024x768.jpg

I plugged or capped all the vents and openings before mixing the "Miracle Heavy Duty Marine/Industrial Cleaner & Degreaser" in a 1:1 ratio with some hot water. The instructions say to use the full quart bottle, but since it wasn't heavily varnished I only used 1/2 of the bottle. Now it's gonna sit for a day and I'll occasionally shake it up a bit or roll the tank around to get all the sides wet and let it do it's thing. The next step will be to let it dry completely and then use the "Tank Etch" to prepare the surfaces and remove the rust so the sealer can have maximum adhesion. I'm hoping to have this done by the end of the week so I can buy some tube and start working on my new front bumper again.

[04 Rocko Taco]

Definitely sounds like some cool stuff. Keep us updated bud.

[corax]

Since the inside of the tank didn't look too bad I only mixed 1/2 of a batch of the "Miracle Heavy Duty Marine/Industrial Cleaner & Degreaser" and let it sit for nearly 2 days. This was the end result, it actually looks cleaner in person than the photo shows.

http://i280.photobucket.com/albums/kk171/batardsalamano/Tanksealer02-beforeetch.jpg

I let it dry in the back of my truck for 2 days (90 degree days with the windows rolled up 3/4 of the way) and poured in the Tank Etch. It kinda sounded like hydrogen peroxide the way it was fizzing, and the tank "popped" from minor pressure building up inside. At this point the directions say to roll it around to thoroughly coat the inside, let sit for 30 minutes, roll around again, let sit for 1 hour and then drain. All I have to do after this part is let it dry again before pouring in the sealer.

[Obi..]

Get a pic before you pour in the sealer? I want to see how well it etched and how it attacked the rusty spot. :D

[corax]

This is what the Tank Etch looked like when I poured it out. It was as clear as water when I poured it in, now it's a rusty/grey color

http://i280.photobucket.com/albums/kk171/batardsalamano/Tanksealer04-tanketchdrainedout.jpg

This is not what I expected to see after the tank etch. It knocked down the mound of rust by the bracket on the far side, but it looks like it spread it everywhere else inside the tank now. I might try to strain the Tank Etch through a coffee filter and try a second treatment.

http://i280.photobucket.com/albums/kk171/batardsalamano/Tanksealer03-afteretch.jpg

[corax]

Here's another pic after the tank etch was allowed to dry for a few days, I also stuck my wife's hair drier into the filler neck for 20 min before the next step.
http://i280.photobucket.com/albums/kk171/batardsalamano/aux%20tank/TankSealer05-beforesealer.jpg

I shook up the sealer and poured it in, rolled it around for a few minutes and then hung it up to drain - the instructions are very explicit about not letting the sealer pool up, so drain it once all the insides are coated. BTW, there was some serious off-gassing when I poured it in (just like the tank etch) that's why the tape over the vent valve at the top allowed some sealer out
http://i280.photobucket.com/albums/kk171/batardsalamano/aux%20tank/TankSealer06-drainingsealer.jpg

The sealer contains a healthy dose of methyl ethyl ketone and is very potent, so when they say "well ventilated" area they mean it. I could literally see the vapors pouring out of the tank filler and vents. As it's drying this stuff reminds me of rubber contact cement, but when completely cured its "dry" to the touch and still flexible - sort of reminds me of a white liquid latex. I wasn't able to peel away the bit that I got on my nitrile gloves, so it has good adhesive properties which gives me some confidence that it'll stay put in the tank. I'm going to take another pic after I put in the second sealer coat and call it a day on this project.

[corax]

Here's what the tank looked like after the first coat (not sure why the pic is so blue, the coating is actually milky white)
http://i280.photobucket.com/albums/kk171/batardsalamano/aux%20tank/TankSealer07-1stsealercoat.jpg

Here's the finished product, after the second coat (still wet in this pic)
http://i280.photobucket.com/albums/kk171/batardsalamano/aux%20tank/TankSealer08-2ndsealercoat.jpg

I let it cure for 1 day after the first coat and 2 days after the second coat before re-installing it. Now I'm just going to wait a few more days before putting gas in it again.