Topic: gas tank restore . Pull dents or clean inside and recoat , Which one first .

[ajf cb 650]

 I am sure there are a ton of links on this , but I am surfing at work and not alot of time to source them .
 Need to remove minimal rust from interior of tank and a few minor dings on outer tank. 
 Should I do the electrolysis method ( never have done this technique before , electricity and water a bit frightening to me ) or Thw works cleaner method .
I plan to recoat interior with Caswell epoxy sealer . The tank is empty now and dry , This is how it was when I bought . unsure of pulling dent with possibile trace of gasoline in tank and having a Boom.

  Any help much appreciated , 72 and beautiful out here in Northern Cal. Damn shame to be stuck inside.

[75cb550 (kyle)]

i would say pull the dent first just to make sure that part gets done. it all depends on the size of the dent. i used the electrolysis method on mine, which worked. it did take out a lot of rust, but i didnt have enough steel left under the rust. also have to guard against flash rust afterwards. will almost rust in front of your eyes. i used ATF on the inside as soon as i got the water out.

i did use the KREEM kit on my brand new tank i bought. it comes with the etching solution, the washer and the liner. i think it was $30-35. per the directions, you just left the etching solution in longer to remove rust and the old chain'o'bolts trick. it worked great for me, but that was a brand new tank. so you may have someone else chime in there....

[greasy j]

i would say pull the dent first just to make sure that part gets done. it all depends on the size of the dent. i used the electrolysis method on mine, which worked. it did take out a lot of rust, but i didnt have enough steel left under the rust. also have to guard against flash rust afterwards. will almost rust in front of your eyes. i used ATF on the inside as soon as i got the water out.

i did use the KREEM kit on my brand new tank i bought. it comes with the etching solution, the washer and the liner. i think it was $30-35. per the directions, you just left the etching solution in longer to remove rust and the old chain'o'bolts trick. it worked great for me, but that was a brand new tank. so you may have someone else chime in there....

+1

dent first.

look up the 'ding king' works great!

I used Kreem, too. worked great, but you have to do it right or it's a mess. make sure it's completely covered and get it all the way clean first, and etched so it'll stick well.

baking soda water will prevent flash rust supposedly, I think it works from what I can tell. but I usually try not to wait around to see if rust is gonna happen, I rinse w/ the soda water after it's done being etched, compressed air dry, then oil if it's being left alone for more than a nanosecond.

[ajf cb 650]

 Does the flash rust happen after you clean it all out and remove the old rust before you used the Kreem , or is this after you cleaned and put the Kreem in ?   The oil used to prevent from flash rust anything specific , is it just enough to slosh it around to cover all the interior ? 
 These may be silly ? to alot , but i am learning .

[75cb550 (kyle)]

once the kreem liner is in, you shouldnt have to worry about rust. i just rinse out with their solution and dryed with compressed air then right in with the liner. if you plan on waiting to for any reason or not lining, just use any type of oil sloshed around inside. just be sure you got as much water as possible out of it. i used atf but motor oil should work just as good.

[greasy j]

once the kreem liner is in, you shouldnt have to worry about rust. i just rinse out with their solution and dryed with compressed air then right in with the liner. if you plan on waiting to for any reason or not lining, just use any type of oil sloshed around inside. just be sure you got as much water as possible out of it. i used atf but motor oil should work just as good.

what he said.

if you do it quick you don't need the oil. whenever you leave bare, especially etched metal alone to get condensation on it protect it w/ oil. I like gibb's oil because supposedly you can paint over it, I always still clean anything I paint w/ denatured alky, but I feel safer w/ the gibbs. and it will prevent rust for 6 mos. w/ one light application. or they have anti-rust light oil in a spray can for garden tools, it's cheap and works well. I put that inside gas tanks that will sit for a long time, but you have to rinse w/ gas or something be4 you use it again.

once the tank is coated with kreem or whatev, though you don't have to do anything. make sure you get a solid coat, if you can see metal poking through it will fail at that spot. you can always reactivate it w/ the solvent (usually mek) and slosh it around a bit more. the kreem bottle is just  enough for a 750 tank if you don't spill any on your shoe.

[75cb550 (kyle)]

yeah i did 3.3 gal tank and coated 3 times. i still have almost a half a bottle left

[TyMatthews]

I just did my tank last month, using the cycle tank sealer kit from KBS coatings.  Their instructions are very well written, and they supposedly have excellent tech support (although I never had to call them for questions).  They also have a number of videos on YouTube showing you how to do each step.  There's a lot of fluff crap in there about how they removed the old tank from some ancient car, so just skip that.  The really useful vids are parts #3 and #4, when they've already got the tank ready to go.  No electricity needed, this is a purely chemical approach.  Best part, you don't have to worry about flash rust because the etching step involves a solution of zinc ions and phosphoric acid... the acid eats the iron oxide and leaves behind a zinc phosphate thin film in its stead.  This film stops flash rust by binding directly with the raw iron atoms, thereby preventing oxidation, and will last you more than enough time before putting the final sealer on. 

All tolled, it was a multi-stage process that took me more than a week with all the drying and waiting.  First stage, wash out the old rust and crap with some bolts and a soap-like degreaser solution.  Second stage is etching the remaining surface rust with phosphoric acid.  Final stage is permanently sealing the tank with a urethane-based sealant that, if done right, will never have to be touched again.  Well, for decades, at least.  You really need to have a completely, bone-dry tank to do the final sealer, or risk having to strip it all out and do it again if it goes wrong.  I didn't want to risk that, so I was extremely patient with it.  Check out my project thread in my sig below for some further details about how I did my tank process if you're curious. 

The KBS kit is the only one I can comment on, since it's the only one I've ever tried; however, it worked well for me and I'm really happy to have it all sealed well.  POR-15 also has an almost identical three-step cycle kit for a bit more $$.  Theirs also includes the zinc phosphate solution to prevent flash rust in between the 2nd and 3rd stages.  My advice, if you go the chemicals route from any of these kits... take your time, be patient, follow instructions to the letter, and you'll be more than satisfied in the end. 

Oh, and pull the dent first!