Gas tanks are supposed to do this, right?

[Negative Ghostrider]

I noticed a drip. Wiped it to determine the source and ended up unsealing 3 pinholes, with possibly at least one more lurking. Jesus this truck is cursed. I really can't do anything but laugh anymore. 

So, what are my options for a new tank?

[datzenmike]

Drain the tank and let dry. Sand down to bare metal. Mix up some JB Weld and cover the area. Let dry for 24 before refilling.

[Negative Ghostrider]

1 minute ago, datzenmike said:

Drain the tank and let dry. Sand down to bare metal. Mix up some JB Weld and cover the area. Let dry for 24 before refilling.

That simple, huh? Alrighty then. 

[ducky]

A long time ago, my dad restored a tank for one of our tractors by refinishing the outside, and then filling it with some liquid that you sloshed around in it, which would dry and seal it from the inside out

 

Not sure what that's called though...

[datzenmike]

The phenolic plastic liner does work but tank has to come out and $50??? Follow directions for best results. It does work though.

 

 

 

There is also a thing called SealAll. In a tube looks like airplane glue. You are supposed to rub a dab of it between fingers till it becomes like a booger then press into the hole.  Best results if clean sanded and dry. Second coat recommended. I used it once on a leaking gas tank like yours. (not clean or sanded) Just rubbed it on and kept rubbing. Gas doesn't bother it. It worked to get me home but didn't last. I think JB weld would be better 

[wayno]

I would do as Ducky suggested, remove the tank, clean it the best you can which will likely create more holes, then go buy the best tank sealer money can buy, do not get cheap, the BEST money can buy as you only want to do this once, then follow directions, they might suggest a small chain, gravel, or fishing weight lead being put in the tank and then shaking the tank around to remove loose/flaking rust, then emptying the medium/rust out and then rinsing the tank out and letting it dry, at this time I would put duct tape over all the visible holes you can find and then using the tank sealer, no matter what you do do not let the tank sealer dry while the tank is sitting flat as the sealer will settle/puddle where the pickup tube is and clog it, set the tank on an end once all the insides are covered and you have drained the extra out,  and then use air every once in a while to make sure the pickup tube stays clear, once dry remove the duct tape and paint the tank and then install it, fill it up and your good to go, it will likely never be an issue again with that tank.

[Negative Ghostrider]

Thanks guys. I'm down with this for a fix but I'm not sure about long term. I recall aftermarket tanks don't really exist. Maybe I'll look into a fuel cel or something. 

[datzenmike]

Get a used one, you are in the PNW heart of Datsunland. Classified ad. You want from '75 through '77 so you have a return line. '78 and up bolt to the frame not the bed like yours.

[Negative Ghostrider]

2 minutes ago, datzenmike said:

Get a used one, you are in the PNW heart of Datsunland. Classified ad. You want from '75 through '77 so you have a return line. '78 and up bolt to the frame not the bed like yours.

This may be a stupid question but does my 73 not have a return line? 

[EDM620]

Very simple quick fix : rub a bar of hand soap over the leaking area. Soap reacts to the gas and seals it. Best 4wd emergency repair, have used this twice, once ea gas & diesel. Lasts decent length of time (car washes will remove)

[Draker]

You can probably still fine one in a wrecking yard

[Negative Ghostrider]

1 hour ago, EDM620 said:

Very simple quick fix : rub a bar of hand soap over the leaking area. Soap reacts to the gas and seals it. Best 4wd emergency repair, have used this twice, once ea gas & diesel. Lasts decent length of time (car washes will remove)

Good to know but hopefully there's not a next time. I was able to drain the the tank into a bucket. Luckily I only had a couple gallons in there. Already picked up a JB Steel Stik. 

[Draker]

JB weld is porous. Give it a go, easy to undo if it doesn’t work. I had a motorcycle and someone has used JB, it would seep out. Maybe it was the wrong type or something.. dunno.

[datzenmike]

12 hours ago, Negative Ghostrider said:

This may be a stupid question but does my 73 not have a return line? 

 

I think not. The return was for '75 and up L20Bs to help with their hotter running. The return line allows cooler tank gas to constantly circulate past the carburetor. There is less chance of vapor lock (gas boiling in the line or carburetor) and easier hot re-starting. A side benefit is the gas is filtered over and over keeping the tank cleaner.

[john510]

JB weld is a temporary fix.I would use the two part slow cure mix,not the stick if i was to use it.If you properly prep the area around the holes,scratching it and wiping clean with acetone you'll get a better repair.

[datzenmike]

I haven't used JB only heard it works. Have used the Seal All under extremely poor conditions (like reach under and rubbed it on) and it worked, though temporarily. Enough to get me home. I don't think JB is porous it's 2 part epoxy binder with very fine metal added for hardness and strength. Preparation is everything.

 

Can't fault the pour in phenolic plastic mix to line the inside of the tank but expensive and a lot of work.    

[john510]

 POR-15 has a tank sealer.It isn't cheap and it requires some special prep and extra chemicals to make it work.I used it on one of my ATV's that had a seepage from a solder/brazed seam.It only held up a year or so.

[jagman]

I own a few old cars that have had similar problems with the tanks.  If the rust holes are not near the drain or the pump outlet,  I use solder to coat he tank exterior and if additional structure is required I use brass screen wire to build up the patch.  Make sure you use a soldering gun NOT a torch and run exhaust from a running vehicle into the tank for 20 mins before doing any soldering. The metal has to be clean for the solder to adhere so I wire brush and use hydrochloric  acid to clean the surface immediately before the operation. Breathing this is hazardous so wear a mask or have a strong fan blowing the fumes away from your face.  Outside is a good place to do this.  The basement can be a real mess if you haven't properly run the exhaust into the tank and bald can be beautiful after the bleeding stops.

[Negative Ghostrider]

8 minutes ago, jagman said:

I own a few old cars that have had similar problems with the tanks.  If the rust holes are not near the drain or the pump outlet,  I use solder to coat he tank exterior and if additional structure is required I use brass screen wire to build up the patch.  Make sure you use a soldering gun NOT a torch and run exhaust from a running vehicle into the tank for 20 mins before doing any soldering. The metal has to be clean for the solder to adhere so I wire brush and use hydrochloric  acid to clean the surface immediately before the operation. Breathing this is hazardous so wear a mask or have a strong fan blowing the fumes away from your face.  Outside is a good place to do this.  The basement can be a real mess if you haven't properly run the exhaust into the tank and bald can be beautiful after the bleeding stops.

The holes are all within an inch or two of the drain, all around. I do have a soldering gun. 

[Negative Ghostrider]

4 hours ago, john510 said:

JB weld is a temporary fix.I would use the two part slow cure mix,not the stick if i was to use it.If you properly prep the area around the holes,scratching it and wiping clean with acetone you'll get a better repair.

OK. I got both. The stick said specifically "gas tanks" on it, where as the 2 part just said "automotive". I'm not terribly well versed in JB-Weld in case you can't tell 😁. I have plenty of acetone and wire brushes from all the paint prep I'm doing. Thanks. 

[datzenmike]

To get solder to tin the steel tank it will need to be dry and clean but more, the iron must be hot enough. I did my 620 tank by removing, emptying then filling with water leaving a smallish bubble with the seam that was leaking at the very top. This way I could use a proper torch for heating and little chance of an explosion. Wet leaves had collected on the seam and pin holed it. I used soldering paste and tinned the tank that cut a brass oval from an old rad and tinned it as well. Put the brass on the tinned area with more soldering paste, heated it and touched solder around the outside of the brass. The solder was sucked into the small gap around the oval.

 

 

[pidge]

Used JB Weld on a plastic boat tank once. Held for about a day or so and began to leak again. It was the two part stuff that turns grey once mixed together. Ended up buying a new tank. 
-Pidge

[john510]

16 hours ago, Negative Ghostrider said:

OK. I got both. The stick said specifically "gas tanks" on it, where as the 2 part just said "automotive". I'm not terribly well versed in JB-Weld in case you can't tell 😁. I have plenty of acetone and wire brushes from all the paint prep I'm doing. Thanks. 

The two part stuff is just a typical epoxy with a filler added.It's gasoline resistant.The issue would be adhesion/bond but good epoxy sticks to pretty much anything except plastic.I've built fuel tanks for boats out of epoxy and fiberglass.It holds up just fine.It will outlast any metal tank in a marine environment.

[EDM620]

Is this a temporary fix or one that needs to be long term?

The soap trick will get you by for a long time. My diesel tank had a skid plate underneath and I ended up with literally hundreds of tiny perforations. I rubbed a bar of soap (one of those little hotel bars should be in every tool box!) then sprayed undercoat over it once dried to keep water away. Put the skid plate back on & kept on truckin' for years.

So - keep your fix away from water & it'll last as long as you need it to.