Light rust in newly repaired gas tank - what to do?

[im3crazy]

Had the typical pinhole leak from a failed gas tank to body seal.

I checked out the tank and there was no sign of ANY rust or other damage- looked new. Then I had a local radiator company boil it out and braze repair the leak. When I got it back, it was a great repair, but it had a light rust coating in part of the tank.

What's the best approach? Can I remove the flash rust with a mild chemical wash, then fill the tank? (TSP, Evaporust etc). Or do I have to go all the way with a POR15 tank treatment?

Searches here showed a few similar questions, but no really good answers.

Tanks in advance!

[ifayeoh]

Go all the way, you are "crazy" after all, sealer por or what ever you can find local.

[Durandal]

are you sure its rust? if the tank was welded on it might just be the rods flux material, it looks exactly like light rust... if you've done any SMAW yourself you should be familiar with its look.

[kcdonahue]

Dave,

I was thinking... Maybe something mild like vinegar that is pretty mild and easy to clean out to get the rust off. Add a chain to give it a little mechanical help while you swish it around. Rinse and dry with a heat gun or in the hot sun...

I also used some eastwoods metal wash in the past with pretty good results on bare metal parts. Not sure how it would do in a gas tank but it works pretty well for keeping the rust off of my welding projects.

KC

[im3crazy]

Thanks for the ideas on this. I'll take another look, but I don't think it's flux spatter - seems just a light spotting- doesn't appear raised or bumpy, and it's light brown.

KC: Good idea on the vinegar, that would be mild enough. I was hoping not ot have to flush water in there, so the vinegar flush and fast dry might work. I thought if I gassed up right after the wash-out I'd be ok without doing any further treatment like a phosphate (TSP).

[bluedevils]

TSP will work, it is the same or similar to Eastwood metal prep. If you fill the tank with gas right after the treatment, it should not rust again. Cleaning with alcohol may also work.