Fiberglass gas tank repair

[Cruiserless]

I'm looking for advice on how to repair my fuel tank (1970 FJ40). It has numerous pin holes on the bottom and and I would like to salvage it. My rig needs a lot of work and I'm not looking to invest too much at this time. I would like to get the tank patched up so I can get it running and evaluate what else has to be done. If all the mechanicals are good I will invest in a new tank later. Some of the threads I found suggested fiberglass as a viable solution but didn't offer a lot of details. I've never worked with fiberglass but catch on pretty quick.
I'm looking for: material recommendations, pictures if you have them, and tips from those who have done it. Thanks in advance.

 

[DiHrdBowTi]

Have you looked at por 15?

 

[DougAustinTx]

This is how I do it. Dump ALL the gasoline out of the tank. Wash the tank out thoroughly with lacquer thinner several times and make sure to invert it and get the thinner in all the crannies, then dry it internally with compressed air. Leave all openings open (filler tube, fuel gauge opening, pickup tube opening etc.) I then stick my nose up to the filler tube and see if it smells strongly. I like to test the cleanliness by igniting a propane torch and passing it over the filler tube. If I cleaned it properly, nothing will happen. On the other hand, if there is still a mix of air and gas fumes, it will poof as it ignites the combination. Because I left the openings open in the tank, it will poof rather than explode because it can't build up sufficient pressure to rupture anything. If all goes well, I can wire brush the corroded area until it is down to clean metal and flux and braze the pitted area. I have been soldering and brazing gas tanks this way since I was 17. I'm 61 now and have never singed an eyebrow doing tanks this way. I used to watch old timers weld up gas tanks wth full tanks of gas and the gas would be on fire as it streamed out of the hole they were welding. Remember, it's not the gas that explodes, it's the air/fumes around the gas. I have attached two photos of the tank from my son's '77 40 that had rusted through at the bottom with lots of holes because fire ants had built a mud nest under the tank that kept it moist. As you can see, the upper holes have already been brazed and the lower holes are cleaned and ready to braze. The brass rod will fill the holes and leaves a nice coating to protect the repair. I assume no responsibility for anyone else's repair attempts, I am simply telling you how I have done it all these years.

 

[Cruiserless]

Thanks for the tips on brazing. My tank has been without fuel for so long there were no fumes. Nevertheless I hooked my shop vac to the fill tube and let it run for about 5 minutes. I have a cheap welder that I used to make repairs to some of the larger holes. By the time I finished up it was dark; I put the flash light in the sending unit hole to check my work and that's when I saw the other 35~ pin holes... I hate to sound like a "PO" patching a 40 together but I am on a budget. Fiberglass sounds like the best solution to repair all the pin holes verses chasing them around with a wire welder as they blow out.

POR 15... heard of it - never used it. Can it be used like fiberglass to build a "shell" around the tank?

How long can I expect fiberglass to hold up?
Where does it rank on the skill requirement scale?
How much should I expect to spend on the materials?
Should I also line the inside of the tank? If so what will work well with the fiberglass (or POR 15)?

 

[baxter650]

I have used this product many times in the past and the latest time when i shortened the tank in my BJ60.
http://www.hirschauto.com/images/autotankkitnew.jpg.
You most likely will have to deal with the larger holes somehow but this should take care of the pin holes.

 

[chevurai]

Don't use fiberglass you won't be happy with it. When it leaks in a short time the old patches will have to be removed to repair it properly. You have had two good responses to the question. Use a product that is designed to repair tanks. Seal it from the inside with a gasoline resistant product.
If your heart is set on the fiberglass repair be sure to write a follow up thread to let everyone know how many days the patch held and if fire was involved.

 

[Cruiserless]

If your heart is set on the fiberglass repair be sure to write a follow up thread to let everyone know how many days the patch held and if fire was involved.

There's one vote against. Any positive experiences?

 

[zebrabeefj40]

If all you want is a temporary tank to test then why not buy a cheap 5 or 10 gallon boat tank? Rig it up in back of the Cruiser for testing. If you then decide to keep and fix the Cruiser you will have a boat tank for your boat or to sell along to the next guy.

FWIW I pulled a tank from a Cruiser that was patched on the bottom with fibreglas. Still had some gas in it but not sure how leakproof it was.

I have used the gas tank repair epoxy from the parts stores to repair various tanks over the years with some success. I'd recommend the POR-15 tank liner kit and some of the gas tank epoxy to get you by if you don't wanna mess with a boat tank.


Nick

 

[Cruiserless]

Thanks for the feedback. I spent the morning welding in patches where the worst holes were. I will look for some POR 15 to seal it up.

 

[bikersmurf]

X2 not fiberglassing. Local club member tried it... A few weeks later he was looking for a new tank.

POR makes a tank sealing product. There are also others. Most rad shops boil the tank out to clean it to ensure good adhesion. I've read of guys cursing POs who used sealer when it started flaking off. If done well, it can be a fairly permanent fix. Personally I'd braze up all the holes and then seal it.

I'd also pressure test it before installing it. I did this recently. I sealed over the filler tube with foil duct tape... I was quite surprised with the pressure it held... Not that I put very much pressure in the tank.