Topic: Rusted gas tank

[at84lp]

I just bought a 1976 honda cb550f and the gas tank has a little rust in it. I've seen many ways to clean the rust including vinegar. Let's say I used the vinegar method and cleaned it out completely. Do have to use some kind of coating to prevent future rusting? If I do what do I use?

[DWS]

I just got done a month ago doing my tank, it was pretty bad, I use the little chains bolts and screws and put it in an old dryer if you don't have the dryer just shake it around as long as you can and then do it again, and then flush it out with your pressure washer, that  should get out all the big chunks and so on out, then I used Apple cider vinegar you might have to keep it in there for three or four days just keep it topped off with water so it is completely full to the top, and to make sure I then used Muretic acid, be careful with that, use baking soda to neutralize it when done, use gloves goggles and  right clothing when using your Muretic acid, always put acid into water , never water into acid, make sure you slush it around very slowly back-and-forth with the petcock out and the whole plugged with rubber, and then put plastic on top and then your gas tank cap, 20 to 30 minutes each time In till you like it, flush out with water mixed with baking soda really good until it is clean, use a hair dryer to dry it out as best you can get most of the all the water out, then use Marvel mystery oil to coat the inside of the tank so you do not get flash rust , you will get flash rust within minutes if you do not do it and just turn the tank slowly upside down back-and-forth do that for a couple days off and on every five or six hours or so, My tank looks brand-new inside.
note: like I said if you use the Muretic acid be very careful do some reading online to know what you're doing with it, and you will be fine. You might not need to if the vinegar works just check it out really good with a flashlight. Do not breath in any of the fumes. Do not get anything on your skin burn chemical burn. I used rubber gloves.goggles, hat, long sleeve, respirator,make sure you have a box of baking soda next to you, and a hose with running water. If you're worried about the paint job on your tank coated with turtle wax and vaseline. I used about a quart Or a little less of the acid.. I used a big tub that my tank would fit into and in the bottom of the tub I mixed water and baking soda so if any of the acid dripped, it would drip into that tub and water mixture.
 Use one or all to get it clean, keep dry. remember gas absorbs water so fill the tank when clean.

[toolguy]

Phosphoric acid, which is the active indigent in commercial rust converters. . .  Sold at home depot as
 concrete etch in the cement department with cement stain. .  about $12 a gallon. .  then neutralize with baking soda. .
It leaves the tank shiny just like new. .
remove the lose junk with a hand full of aquarium pebbles first. .

[flybox1]

Phosphoric acid, which is the active indigent in commercial rust converters. . .  Sold at home depot as
 concrete etch in the cement department with cement stain. .  about $12 a gallon. .  then neutralize with baking soda. .
It leaves the tank shiny just like new. .
remove the lose junk with a hand full of aquarium pebbles first. .

+1
Kleen Strip Prep-n-Etch is the way to go.
hand tumble some gravel in the tank first to loosen the majority of it.
shake out the rocks and water rinse out the tank as best you can.  get as much rust out as possible.  dont worry about flash rust here.
I added a few dozen old golf balls to take up the volume of the tank before I poured in one gal of the prep-n-etch.
topped it off with water.
after about 3 hours of sitting, i drained out the tank into a 5 gal pail.  the prep n etch leaves a nice gray phos coating.
work quickly from here to minimize any flash rust.
water rinse the tank really well.
if the tank is going to sit empty, pour in a pint of Marvel mystery oil and give it a good shake.  cap it and shake it every few days.
if the tank is going into service right away, you'll need to rinse the water out.
I used old gas.  2 rinses with a pint each.  and then fill up with good gas.  Done.

[Retro Rocket]

Phosphoric acid, which is the active indigent in commercial rust converters. . .  Sold at home depot as
 concrete etch in the cement department with cement stain. .  about $12 a gallon. .  then neutralize with baking soda. .
It leaves the tank shiny just like new. .
remove the lose junk with a hand full of aquarium pebbles first. .

Try and avoid rust converter getting on the paint if your not painting, some converters don't like paint at all....

[flybox1]

Phosphoric acid, which is the active indigent in commercial rust converters. . .  Sold at home depot as
 concrete etch in the cement department with cement stain. .  about $12 a gallon. .  then neutralize with baking soda. .
It leaves the tank shiny just like new. .
remove the lose junk with a hand full of aquarium pebbles first. .

Try and avoid rust converter getting on the paint if your not painting, some converters don't like paint at all....

+1
Prep-n-etch did not harm my paint/clear(spraymax2k)

[at84lp]

Thanks a lot. Appreciate the inputs from everyone

[Patrick]

I like the muriatic acid bath approach with one variation, taught to me by an old guy at an old radiator shop. Cean it with acid, but then wash it out with a strong mixture of laundry detergent. Laundry detergent is based on lye, which is a base, which neutralizes the acid. It mixes with water easier than baking soda and the detergent mixture gets in all the same crevices as the acid. Leave it in the tank for half hour, 45 minutes, then rinse with the hose and compressed air to dry. No oil, or gasoline is necessary. If you do it right, you get no flash rust. If you do it wrong, do it again. I treated my K0 tank using this method in 2008. Most of the time since then it has sat empty in the garage. I have had no rust return.

Patrick

[78whiteorbs]

Use to be a murat in acid and chain kinda guy and it worked great but have since switch teams to evaporated as it is non corrosive , the fumes are minimal and won't kill me and it is completely safe for paint which is a BIG plus. Also it's reuseable.....beat that.

[DWS]

Electrolysis is a cheap way to go if it's not too bad Try them all, have fun