On the road again at 40.............the bike that is..........PART DEUX

On my 77D I did the vinegar in the gas tank trick and it cleaned it up like new. This tank was in worse shape so I've had the vinegar in for a few months now. It has cleaned up the top of the tunnel fairly well and I guess got to the point where the last bit of rust was what was sealing the tank.
Didn't clean out all the rust in the bottom of the tank though, so still some work to do there.

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Today I noticed vinegar all over the bench. Two or three small pin holes have developed up in the tunnel.

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So, still need to do something to clean out the rest of the rust.
What's the best route to follow for the pinholes? Get it welded? Sealer? Or both?

I'm not happy with these pinholes but I guess better now than after it's repainted.
Gas may well have produced the same result down the road.........so to speak.
 
Robin, muriatic acid (driveway cleaner) in a 28% or higher solution will have the rust gone in less than 30 min. It's nasty stuff though... wear a respirator and stay downwind. Oops... meant upwind. Most hardware stores carry it.
Not a fan of sealers. Trying to weld up pinholes just generates more pinholes... 'cause the base metal is just too thin. Brazing would most likely have the same result... although the lower brazing temp might just do the job. Ideal fix would be to cut out the bottom metal, fab new pieces to TIG in. Never have to bother with it again... which you can't say 'bout sealers.
 
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You could try a tank sealer...there are some two part epoxy types that will seal the pinholes. Another, and probably better, route is if you know where the pinholes are, you could braze them. I had a few small pinholes on my tank that was fixed with brazing...worked great...fairly easy.
 
For rust, I have been very happy with Evapo-Rust. Non-toxic, works fast...about a day or two and your rust will be gone. Have fixed a few rusty tanks with it...happy with the results.

Here's what I do: Fill the tank with it...let it sit, empty the solution (Can be reused btw), rinse the tank out with distilled water...and then follow it up with some denatured alcohol (will help remove the water that lingers)..drain and done. You'll want to fill it with fuel sooner than later so you prevent flash rusting.

If there's a lot of rust built up, then I have a short 1-2 foot bit of chain that I toss into it with the Evapo-Rust and every few hours I'll go and shake the chain around inside the tank letting it slide across the walls, etc. and keep doing this for a day or two. Then follow the above steps.

Note: If I'm going to let the tank sit for a while without filling up with fuel, then I spray the entire inside with WD40 so that it coats the walls. Then simply fill with fuel when ready.
 
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A long time ago I fixed a pinholed lawnmower tank with solder. Leveled the tank, dropped a teaspoon of flux down in it. Cut up about 1/4lb. of solder and dropped it in the bottom... and heated the outside with a propane torch 'till the solder flowed out flat. It never leaked again. 'Course, that was prolly back in the day when solder was mostly lead. Just a thought...
 
Ok, thanks Jim. I'll get some muriatic acid and then test again to see how many more holes develop. And will go from there. Watched a metal artist from the area forming headlight buckets and gas tanks at a swap meet this summer. If a replacement piece is required he'd be worth talking to.

Thanks Brassneck, I'll look into that.

Haven't tried Evapo-Rust, but I did try Metal Rescue on my other tank and found good old acetic acid worked better.

Thanks for the ideas guys!
 
Well, about a half an hour with Muriatic acid sure did the trick Jim. No chain assist required.

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No additional pinholes appeared. Just those 3 original drips.

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So I can see where it needs to be brazed. Checking around to see if anyone I know has a brazing kit I can borrow to do some practicing with first.
If not, I'll look into the cost of getting a rad shop to do it.
Depending on how much that is I may just add an Oxy-Map torch kit to the 'Tools I just HAD to buy' shelf. ;)

There will be more tanks to do right?

Thanks again for the ideas guys. :)
 
Be careful. Tanks can explode. From 1980 to 1986 I owned a radiator shop. Fixed a lot of gas tanks off of cars and trucks. Very few bike tanks. Only way I would work on a tank is after boiling it out in my hot tank. Gas will get into the pores of the metal. The hot acid would go into the metal and "eat" the gas. An old boy not to far from where I lived did it wrong one day. Wasn't pretty. My minimum charge was $20 back then. Had a customer complain about the minimum. Explained to him if it blows up I'm probable dead and he's out a tank and a dozen roses, I would fix it for free if he wanted to stand next to me while I fixed it. His reply was " I'll pick it up when you tell me it will be ready". I Know there are other ways of fixing them. Flush with soap and water, fill with inert gas etc. Hot tank was how I was taught, never had one blow.
 
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Funny you mention that. Back when I was in welding school ( when dinosaurs roamed the earth ) they drilled it into us to never weld gas tanks for that very reason. They have to be chemically flushed to be safe.

I butted heads with the shop foreman , at a garage I usd to work at, and damn near lost my job for refusing to weld a gas tank from a truck , that one of the mechanics assured me it would be safe to weld because he flushed it out with the steam cleaner.

I won, and kept my job and my head. They sent it out for repair.
 
Good to know GLJ. Thanks for the heads up. I'll check around the area and see if there are any pro's that will tackle this.
Glad you made out OK in the work you did.

I'll check with my machinist/vintage bike mechanic who did the rebore on my other bike. He'll know someone I'm sure.
 
I was just about to edit my post. Robins gas tank has been soaked with vinegar ( acid )
Then soaked again with muratic acid. It might very well be clean enough to weld. If it still smells like gas, I’d be cautious.
 
No gas smell now Bob, and I didn't stick my nose down there to smell the acid. :yikes:
Would have been tough with my respirator mask on anyways.....

I'll start by asking Terry eh? Dollars to donuts he knows someone after 40+ years around this industry.
 
Prolly gonna regret saying this..... but I've welded tanks by washing out with hot soapy water.... and then run a tube from my truck exhaust for 20min. Carbon monoxide is an inert gas after all.... Please don't try this at home. :yikes:
 
Haha Jim. I read about doing that while doing some research. I do have a lot of large enough diameter hose laying around (nuther story) but I think I'll start by asking Terry........:D
 
but I think I'll start by asking Terry........:D
Yup! Discretion is the better part of valor. ;)
I gotta admit that after being a lot older and wiser..... I can't believe I was actually young and dumb enough at one time to do that. Can't say as I'd willing to do it again.
 
Well Jim, if we started a thread on the dumb things we all did when we were young.....whooooo boy......

Then again, would we all fess up to it? :shrug:
 
After I flushed mine for rust treatment, there wasn't any issue with the tank blowing up when I had to braze it. I will say though that I was a bit worried...so I put it out in our yard and hid behind a wooden bench we have back there. With a broom handle, a coat hanger and a mini torch, I dangled the flame over the gas cap area and inside the tank...nothing happened of course, but I was glad to have taken the steps to verify that. I'm sure there's a better way to do that...but it worked for me. :)
 
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