Fuel tank repair

[Drivewayboater2]

Greetings. Question regarding repairing a pitted fuel tank.
Back story-a few years ago I purchased a product called alumilloy. It was to repair broken aluminum tabs, and or repair aluminum parts. I used it mainly for repairing aluminum engine blocks. I spent the last 30 years racing go karts. The engine blocks are made of aluminum.

I yanked the fuel tank out of my 1990 Bayliner 2651 and found some pitting. Not bad but nonetheless pitted. Here’s a pick of the pitted area after using a wire wheel. Aft section of the fuel tank. Note I did not use my angle grinder yet. Just cleaned up with the wire wheel.


Today did a bit of experimentation.
I took a piece of 1/8 aluminum and ground away to more than 1/2 the thickness in a 2” x2” section. Used my acetylene torch to heat up the piece and used the alumilloy product to fill the entire ground away area. Here’s a pic of the experimen.





after letting it cool I tied to chisel away the entire piece of new area. To my surprise it bonded very well. I could not get it to separate.
Now I’m thinking of doing this on my fuel tank. Any thoughts?

 

[matt167]

Given I know someone who just about blew himself up, and burned his shop down welding a gas tank…. I would advise against it. There are ways. Filling with water is sometimes the answer. That’s a lot of water.. I’d have a new one re fabricated

 

[tpenfield]

Many/most welding shops won't repair a used fuel tank, and for good reason as Matt mentioned.

If the tank is 0.125" thick aluminum (check the certification label), then it is probably done. Even if it were 0.019" or more thick aluminum, I'm not sure I'd want to have it repaired . . .

The area of pitting looks fairly wide-spread and deep. I'd go with a new tank. I have pulled out 2 fuel tanks of my boats . . . One the had less pitting than what you are seeing, and I replaced because the pitting was about 50% deep vs. the material thickness and the tank was only 0.125" material.

As for working on a fuel tank, the challenge is to fully purge the fuel & fumes.

I'd have a new tank made . . .

 

[Drivewayboater2]

Thanks both.

 

[Chris1956]

You can use some epoxy putty like marine-tex or JB weld and some fiberglass cloth to repair it. Clean the area with acetone, apply the putty and work the cloth into the putty.

From the looks of it, if you cover all the pitting with the putty and cloth, it should last a while. Flexing of the fuel tank will be bad for the patch.

 

[Scott Danforth]

I would get a new tank

 

[dingbat]

Made a couple of customs and welded up a couple of fuel tanks back in the day.

As noted, you either have to fill the tank with water or purge with nitrogen or argon. This is only after cleaning inside with detergent and water to remove any fuel residue.

From a repair standpoint, I wouldn’t bother trying to repair pit corrosion. The metal is compromised. Needs to be removed and replaced. Anything less is a band-aide.
Personally, I’d just order a new tank and be done with it

 

[Bondo]

Ayuh,.... That gas tank is Junk, scrap it,...... I've found these guys to have an outstanding selection of marine gas tanks,......
I've bought several from them,.....