Rusty gas tank repair - Cut-Weld-Drive Forums

honu · May 20th, 2012, 02:53 PM

I'll save the gory details... suffice to say, I gotta rusty gas tank. I followed one suggestion to pour coarse sand and gravel in it and shake it good for a couple of hours and it really did seem to scour out much of the heavier rust deposits, but I'm left with some pitting and light residual rust.

I'm hesitant to go with the more extreme methods, such as muriatic or phosphoric acids... I suffered an acid burn several years ago, so I'm a bit gun shy.

Another suggestion was to use straight white vinegar. It's a weak acid, so it might work, given time. My question is, has anyone here used that method... or what method did you use to clean the tank?

I checked using the "search, but found nothing pertaining to this issue.

Thanks for any advice...

bigguy · May 20th, 2012, 03:09 PM

length of chain or alot of bolts and shake and repeat.

rostigbug · May 20th, 2012, 06:42 PM

I just let the sh!t stay in mine. I put on a fuel filter & let it catch all the sh!t

bigguy · May 20th, 2012, 06:51 PM

Cause we know half assing things is in your vocabulary. Why would we expect anything less from you. Take the time and fix things right and you wont have to fix the shit over and over again.

fungus · May 20th, 2012, 06:54 PM

Honu, it sounds like you're on the right track. Here's a ghetto-rig I used for this purpose one time.

I made a small "trailer" for my bicycle, but I made the wheels from plywood and purposely made the wheels off-center. Makes a hell of a lot of noise and it'll throw you if you're not careful, but it shakes small tanks and mixes cans of paint very well.

Perhaps you could do one for a car since your VW tank is larger than the motorcycle tanks I did?

Unless you can make custom bent nozzles for a sandblaster, you're not going to get much better than the method you're currently using. A little surface rust won't hurt anything. And be absolutely sure to run a fuel filter with everything.

I think POR-15 has a tank kit?

honu · May 20th, 2012, 07:01 PM

Perhaps I should've waited before posting my question...

I put two gallons of white vinegar in the tank and sealed all openings with tape or plugs, then let it set for about 6 hours. Just checked it and found a ton of rust flakes floating in the vinegar solution.

I poured it out and was amazed at how much junk came out with the vinegar. I looked inside and I'd venture to guess, 3/4 of the old rusty scale had been dissolved and lifted off.

I rinsed the tank and poured another couple of gallons of fresh vinegar in, gonna let it set over night... see what it looks like in the morning.

I also threw all my old, rusty fender bolts and washers in a jar when I filled the tank the first time... they're absolutely free of any rust or scale.

Pretty amazing for a couple of dollars worth of vinegar...

triker_Chewie · May 21st, 2012, 12:22 AM

i used the laundry soda battery charger method on my chopper tank. you could fill the tank with the solution and put a rod down inside the tank. dont short it out tho

honu · May 21st, 2012, 01:14 AM

Quote:

Originally Posted by triker_Chewie

i used the laundry soda battery charger method on my chopper tank. you could fill the tank with the solution and put a rod down inside the tank. dont short it out tho

I may try that if this batch of vinegar doesn't get all the rust out. Should be fairly easy to do, just drop the electrode down through the opening for the fuel level sender.

rostigbug · May 21st, 2012, 03:48 AM

Quote:

Originally Posted by bigguy

Cause we know half assing things is in your vocabulary. Why would we expect anything less from you. Take the time and fix things right and you wont have to fix the shit over and over again.

**38Chevy454** · May 21st, 2012, 11:47 AM

Sounds like your first mechanical cleaning and then the acid (vinegar active ingredient is acetic acid) cleaning will get you the results needed. That is about the best way, get the loose and bigger stuff out with the mechanical style cleaning. Chain does work good and is easier to make sure you get it all out as opposed to loose rocks. Bugdust's idea to have some way to shake it around beats doing it by yourself. Dump ouot all that loose stuff and then chemical cleaning will get the rest. Make sure to have the vinegar coat all the inside surfaces.. Rinse with some baking soda solution to neutralize the acid, then flush that out with water. Put in the sun to air dry and you should have a tank ready to go back in the car. Run a filter as suggested.

honu · May 21st, 2012, 06:21 PM

Quote:

Originally Posted by 38Chevy454

Sounds like your first mechanical cleaning and then the acid (vinegar active ingredient is acetic acid) cleaning will get you the results needed. That is about the best way, get the loose and bigger stuff out with the mechanical style cleaning. Chain does work good and is easier to make sure you get it all out as opposed to loose rocks. Bugdust's idea to have some way to shake it around beats doing it by yourself. Dump ouot all that loose stuff and then chemical cleaning will get the rest. Make sure to have the vinegar coat all the inside surfaces.. Rinse with some baking soda solution to neutralize the acid, then flush that out with water. Put in the sun to air dry and you should have a tank ready to go back in the car. Run a filter as suggested.

The vinegar does seem to be working, but at a pretty slow pace. So far, I've dumped and refilled the tank three times and each has produced a lot of rust flakes.

It difficult to see more than a fraction of the inside of the tank, so I'm sorta making a S.W.A.G. (scientific wild azz guess) on how clean it really is.

If after this next rinse, there are still a significant amount of rust particles, I may just step up to a weak muriatic acid treatment.

Definitely gonna use filters, probably two at least until I'm sure no gunk is coming through from the tank

ClassicGMJunkie · May 22nd, 2012, 10:57 AM

once you get the crap out, a pint of MasterSeries silver can go in, move it all around and get it all covered, let the excess pour out to reuse somewhere else. its a killer tank sealer. meanwhile both of my gas tanks are setting with white vinegar in them (evaporated by now) so it should have separated the rust's molecular bond with the good metal... and caused more.

honu · May 22nd, 2012, 11:15 AM

Quote:

Originally Posted by ClassicGMJunkie

once you get the crap out, a pint of MasterSeries silver can go in, move it all around and get it all covered, let the excess pour out to reuse somewhere else. its a killer tank sealer. meanwhile both of my gas tanks are setting with white vinegar in them (evaporated by now) so it should have separated the rust's molecular bond with the good metal... and caused more.

Thanks for the tip... I was gonna use some type of sealer to prevent a repeat of this fiasco.

I kno what ya mean by creating more... I spilled a little on the outside of the tank, which, of course, I'd just sanded to metal. Within an hour, there was flash rust anywhere the vinegar splashed. I hit it with a Scotchbrite pad and sprayed it good with WD40, seems to be keeping the rust at bay.

nhtriker · May 22nd, 2012, 04:39 PM

" Rinse with some baking soda solution to neutralize the acid, then flush that out with water. Put in the sun to air dry " You can speed this up by "rinsing" the water out with a little bit of acetone. That used to be part of the instructions for Kreem brand tank liner.Don't think that is sold anymore...

Pop · May 22nd, 2012, 05:59 PM

I bought a VW camper one time that had dried gas in the tank. After taking the tank out and cleaning it, I used an old glass sediment bowl like was used on cars in the 40's and 50's and kept checking it and removing the crap until it stayed clean and then put the stock filter back on. They are also used on farm tractors and some lawn tractors and Tractor Supply has them. Pop

**38Chevy454** · May 23rd, 2012, 05:48 AM

Quote:

Originally Posted by nhtriker

" Rinse with some baking soda solution to neutralize the acid, then flush that out with water. Put in the sun to air dry " You can speed this up by "rinsing" the water out with a little bit of acetone. That used to be part of the instructions for Kreem brand tank liner.Don't think that is sold anymore...

I almost suggested to use an alcohol rinse to help get the water out and let it dry better.

Actually alcohol is better than acetone. Alcohol will mix with the water and evaporates leaving almost nothing behind. Acetone displaces the water, but does evaporate very quickly. It could still leave a small amount of water behind in crevices. Acetone is a better solvent to cut any oil residue, and would be a good idea prior to any coating operation, similar to wax and grese remover wiping prior to paint.

I am always leery of any sealers, especially with the new gas having the alcohol and other stuff added. Seems to be a lot of examples of the sealers being affected by the new gas. Which creates another probolem when the sealer degrades.