When I first bought my truck it didn't have a gas cap. I don't know how long it sat without one, but the stock tank was full of scaley rust that would get mixed around when filling up and then settle to the bottom pluging the outlet. We tried the tumbling methods, but it didn't work so we mechanically cut (no torches) a section of the back off to get access to the interior. We used some sanding and scraping to remove the scale to bare metal. We then coated the inside with fiberglass resin. We then used fiberglass mat and resin to reattach the removed section.

This worked fine until the first time I filled the tank over 3/4. With the tank that full there was enough pressure to crack the seal of the fiberglass. So what would you do? I know I could buy a junkyard tank, but I would likely have the same problem I started with. What I am considering is removing all of the fiberglass, using rivets to attach the panel then use fiberglass or some kind of epoxy to seal up the seam.

 

I would replace the tank. Safety first.

 

I appreciate the feedback, but I haven't seen any reproduction tanks for the 48-52 trucks. If I get one from a junkyard it is likely to lead me back to square one. I know I have heard people talk about the tumbling with chains/bolts inside, but that didn't work. I know my tank is rust free and I know there are products that can patch a tank. To me that's far better than another rust-filled tank.

 

Ditto! Replace the tank. I went new and gave my rusty one to a friend to renovate so that I could avoid the hassles. Many on this site have cleaned their tanks with various solvents and used the correct sealing componds from various suppliers; all with good results. Your method is the first that I have heard of that involved cutting the tank. So cut your losses and find a new (old) tank and have it restored at the local radiator shop ($125?). Good luck, Jag

 

The gas (a solvent) weakened the fiberglass and will do so again if given a chance. Like others, I would recommend a replacement tank. Now may be the time to consider moving the tank from it's original position.

Now, that said, there is a product that might help with your seams. I think it is a muffler mender product that also says you can use it on gas tanks. That may be an option. Under the right circumstances you could have a new patch welded in, but this is a "don't do this at home project" It involves, cleaning and purging, and inert gassing and lots of other stuff.

Far easier to replace the tank, maybe not what you want to hear but safer in the long run. After all, you would not want to lose your truck and all the hard work because of a leaky tank, right?

Bubba

 

I have considered moving the tank and haven't ruled that out. I am trying to figure out a place to have the tank under the bed, but still have room for a spare. Where do those that have the tank at the very back put a spare? In the bed or no spare are not options I like.

 

Years ago I had a mechanics shop weld the gas tank on a company truck. First he drained the tank. Then he backed his personal vehicle to the entrance of the repair bay and put a hose in the tail pipe and stuffed a rag around it to seal it. The other end of the hose went in the tank. The gas line was open as well as the port for the sending unit as vents. He let it purge for 5 minutes or so and then he started welding. I watched all of this . . . from a distance. He claimed that he had done it many times. You could do the same thing using nitrogen as a purge. I am not recommending this as a wise solution, take it for what it is worth.
Scott

 

I have drained the tanks, and then filled them with water, and brazed (gas torch and brass rod) holes in tanks, repair filler necks and such. As long as the tank is filled with water, no kaboom. Drain the water out and let dry and use dry gas for a couple tank fulls....

 

2speed, I thought I had heard of people doing that, but I didn't ask about it as I figured the response would be strongly negative.

Aren't there gas tank sealers that can be put into a tank and swished around that will hold the rust at bay? I am refering to a tank that doesn't have a 1'x3' hole in it. What are the names or where can they be bought? At the time the tank was cut apart I had no idea that such sealers were available.

 

It's a trade-off putting a new tank where the spare goes. You might be able to find a tank to mount ahead of the axle like a saddle tank, not sure what the options are but there are lots of tanks available--you'll just have to count on at least a little fabrication to mount it. I put a mustang gas tank on the rear frame, and will go without a spare for now. In 15 years of driving I've only had 1 blowout, that was on really worn older tires. However, I've had plenty of slow leaking flats. When my truck is done I plan on keeping a couple of cans of fix a flat and a mini air compressor (kind that plugs into the cigarette lighter) under the seat, those should last long enough to get me to a tire shop for repair if needed. That and I have brand new tires now so I figure I'll be better off.

Or I just jinked myself by saying I've only had 1 blowout.

Scott

 

One thought has crossed my mind about a spare: Most people that hot rod a truck go with a car IFS. So if you had a donut style spare that fit and was the right size you might be able to find room for it behind the seat where the tank had been. I don't know if you can just buy a donut of any size tough, so it would probably have to come from the donor car that the IFS came from and you would have to have tires of the same height as the stock ones.

 

Check Hemmings. Bill Hirsch sells an etcher and gas tank sealer that will probably work. I've used it with success....

 

As one can well imagine rusted out gas tanks were a common problem when I lived in Buffalo NY. We welded up dozens of tanks using the fill with water method and not one boom. We'd run a torch flame across the neck of the tank before we started welding just to be sure. The dump it in shake it around pour it out sealer is called gas tank slushing compound.
You may have given yourself a problem tho. There is a major difference between epoxy resin and polyester resin, polyester resin breaks down from exposure to gasoline!
You can tell which you used by their mixing instructions. With epoxy resin you almost always mix equal parts of resin and hardener together and the kick or hardening time is governed by the chemistry itself and cannot be altered to any great degree. Polyester resin on the other hand comes with a small bottle of a liquid hardener that you add to the resin typically by the drop and the kick or set time is variable depending on how much hardener you add. If you used polyester resin inside the tank you'll eventually have more problems than the rust made. Even epoxy resin isn't going to hold your gastank together by itself tho you'll need to use a reinforcing strip across the joint sealed with some of the epoxy ribbon sealer designer for exposure to gasoline and pop riveted or metal screwed together every couple inches. The patch needs to be strong enough mechanically to hold together without the epoxy it is too brittle to be structural it just acts as sealant. You could paint the outside with POR to seal any pinholes. It would be much cheaper and safer to do the underbed tank conversion and use a space saver spare. Don't worry too much about the diameter of the spare matching the other tires as long as the bolt pattern matches and nothing drags on the ground. They are only meant to get you someplace close by where you can get the flat tire fixed or replaced. You could also consider adapting a saddle style tank if you must have the spare underneath.

 

I agree with the others. I took my tank to a local radiator shop. He boiled it out several times, cleaned it up, and resealed it for me. Not one problem since. It only cost ne $100.

Good luck,
Vern

 

AX, you are a very knowledgable person, that or you can convince us all that you know what you're talking about. If its the latter, have you considered politics?

Seriously though, that was a great response. If I keep the tank I have I will probably try to remove the resin from the inside as I don't know what it does with heat. I don't want it melting off. I would then do the fill-with-water-and-weld method.

I know there is another thread devoted to suitable tanks, but I only remember talk of behind the axle tanks. I am assuming that the saddle type tanks are more common on trucks than cars, right? The tank needs to fit between the frame rails, so a full size truck that is new enough to have a saddle style tank will have too wide of a frame, so I want to look for a Ranger tank, right? I am a long ways from taking any action on this, I'm just trying to plan everything out.