multiple leaks in one small area of the gas tank

[ZGjethro]

About a month ago, I power washed an epoxy plug off of my fuel tank. Since then, I have pulled the tank and discovered that the tank is made of two identical stampings welded together. The slight hump designed to accommodate the filler tube on the top of the tank is a slightly lower part on the bottom half of the tank. I have eight pin holes in about a one inch circular area in this area. If you look on your truck, this lower part of the tank is the front left corner. The rest of the tank seems solid, and I stuck my phone camera in the tank today and took a few pictures. It is rust free except for a little rust on the spot welds on the baffles. My questions are two: Is this low point of the tank prone to rusting due to water accumulating there? Do tank lining chemicals work well? I am thinking of using this product http://www.caswellplating.com/caswell-e ... -pint.html

[refit1701]

I'm going through three tanks and even though they have rust on the inside, they seem to be prone to pitting on the outside over time as moisture forms on the ground facing side. I am going to use acid etch to clean as much rust out as possible and then use one of the commercially available tank liners (like the one you linked to) to seal up mine. Unless you want to risk welding on it.

[Brett]

I had quite few pin holes in my tank. I thought the tank was pretty good until I cleaned it out with degreaser, and scraped and sanded the out side. I ended up soldering up all of the holes in my tank and using it without a liner. I had heard some mixed results of the DIY tank sealers, and I figured I could always seal it later on if I needed too. It's been about 4 years and so far so good. If you want to use a sealer, I would still recommend soldering up the holes first so that you're not relying on the sealer to bridge the holes.

Brett

[ZGjethro]

Brett, any special solder recommended? I'd probably use my hotter soldering iron (gun style, not pen style), water based plumbers flux, and electronics solder.

[w30bob]

Hi Guys,

I've also soldered up pin holes in a tank....worked fine. I used a propane touch (like I was sweating pipe) to cover a larger area than a soldering iron can. I just kept a good size area hot and spread the solder out with a flap wooden stick.......like the body guys who use lead filler. Barely had to sand it afterward and once painted you couldn't tell it had been repaired.

Of course anytime you apply heat to a fuel tank you have to be extra cautious. I attached the exhaust from my car to the tank filler inlet pipe while I was soldering....you can also fill the tank with water. If you choose to do nothing be absolutely sure that tank is clean with no remnants of fuel vapors....or you'll be reading these posts from the other side (if you know what I mean).

regards,
bob

[ZGjethro]

I read about flushing the tank with acetone or MEK and rinsing with water to get rid of any fumes. I like the idea of running your car exhaust thru the tank also. The torch seems like a better way to get a lot of solder on the tank.

[ZGjethro]

I bought the Caswell gas tank epoxy coating system. $97 after shipping! I am going to clean the tank with acetone, and then rough it up inside with a bunch of small nuts. Then I am going to fill the tank about 95 percent with water and do an external solder repair before lining it. From a lot of internet searching I have decided to use hardware store "silver solder". Its a little tougher than 50/50 plumbing solder but not real jewelry silver solder. I have never brazed, and my little MIG machine would only burn holes in the tank with me running it. Does anyone here have any advice for me?

[w30bob]

ZG,

Propane torch is your best friend in this instance. Real easy to control the heat (just move the flame out of the solder) and you can cover a good sized area. Use a good flux, heat it up until it smokes, lay the solder on top and use the torch to melt it. You really can't over-melt it, it just gets nice and shiney and flows out. Move it around with a flat piece of wood while keeping the solder liquid, then heat the whole area one more time and the heat will smooth out the solder very nicely. If you're doubtful try it on a scrap piece of sheetmetal you have laying around first. Really no great skill involved.....as I can do it.

regards,
bob

[ZGjethro]

thanks Bob. I should have mentioned I will be using propane. I don't think my iron will put enough head into the metal to get solder to flow well.

[ZGjethro]

Complete failure to solder the tank. I used 96% tin- 4% silver solder first. After that failed to bond I used 50/50 and plumbing flux. The flux seemed to darken and inhibit adhesion. I wire brushed the tank again with a rotary drill brush and started new. I got some adhesion with flux core solder, but nothing that I would trust. I took it all off and sanded the tank clean again. What I had hoped was an easy repair is looking more difficult. I might try another flux

[ZGjethro]

Tomorrow the tank goes to the radiator shop 45 miles down the road. It is time to let pros with the right tools do the job. I don't have a brazing or cutting torch, and my mig welder in my hands is not confidence inspiring. I am still searching for a better tank. If anyone here knows of one, let me know

[ZGjethro]

For anyone who followed this thread, I recently got the tank back. The radiator shop soldered a brass plate over the small area with multiple holes. I coated the inside of the tank with Caswell platings gas tank lining kit. It is a two part epoxy kit meant for 20 gallon tanks. With the baffles in the tank, and it being 25 gallons, the coating was spread pretty thin. I did not have to pour out any extra epoxy. It has dried into a hard coating covering pretty much every surface. I stuck my cell phone in the tank and took a bunch of photos, and there are only a couple of really small spots which I missed. If I had a good tank to line, I would buy two of the kits and guarantee coverage of all surfaces. The problem is that one kit was $97 after shipping. I definitely focused on coating the bottom and sides of the tank, since I only had rust on a small area of the bottom of the tank. Now I am waiting on some TM9 OD2430 spray paint to paint the tank.