TheSamba.com :: View topic

Sun Aug 18, 2013 7:18 pm

if it were me, i would try lacquer thinner. that shit eats anything, and seeing that the stuff in the tank is still curing, i would almost bet it will come right off

Sun Aug 18, 2013 7:18 pm

Here in Toronto there's a tank renew place that cuts a hole large enough to allow the inside to be sandblasted, welded shut, cleaned and then the sealer is applied. I had my tank done 3 years ago and I've had no issues.

Sun Aug 18, 2013 7:25 pm

I thought the reason for sealing tanks was because of rust, not leaks. Am I wrong?

What will ATF do that gas won't undo?

Sun Aug 18, 2013 7:54 pm

I only seal if the rust goes right through, muriatic acid and a followup with rustmort/ospho removes all the loose crap and the ATF prevents flashrust until there's gas in it on a bare metal tank.

Sun Aug 18, 2013 8:08 pm

Thanks again everyone, it seems like its peeling even more on its own, got it soaking Ina coat of brake fluid, degreaser, and easy off. I'm gonna work on it some tomorrow, if I can get this handled, I can start getting the old girl put back together and hit the road!

Sun Aug 18, 2013 8:17 pm

I will never understand why people use muriatic acid. Hydrogen chloride gas is one of the most corrosive gases in existence - the moment you remove rust in one spot, you're creating it in another.

To the ATF question, ATF is just a (relatively) thin oil, so you're coating it in oil to prevent rust. Works in the short run, but long-term, it's not going to really do a whole lot.

Were it me, I would pour a quart of xylene in, and see what happens. If that doesn't work, get it boiled out for $50 or so.

The best way to remove rust in your tank is electrolysis. It is dirt cheap and extremely effective.

The best way to prevent rust in your gas tank is to use a phosphoric acid treatment, rinse it out and air dry it, and forget about adding some whiz-band topcoat. Iron phosphate is inert and won't hurt anything because there is nothing to peel off.

Sun Aug 18, 2013 8:20 pm

How about acetone nail polish remover.

Sun Aug 18, 2013 8:28 pm

guitarman63mm wrote: I will never understand why people use muriatic acid. Hydrogen chloride gas is one of the most corrosive gases in existence - the moment you remove rust in one spot, you're creating it in another.

Because it gets the rust out in a hurry and it's cheap and easy to use, TSP is a strong base and neutralizes it if you are lazy on the rinsing but I like the phosphate treatment right after myself followed by a drying and oiling.

Any better options you can suggest for home use?

Mon Aug 19, 2013 8:37 am

After having coated several tanks with POR15 the one thing I'll say is that it bubbles...but just because you see bubbles inside doesn't mean that the metal isn't solidly coated...it's just that there are bubbles where the top of the bubble popped and you might have that debris sloshing around. It seems that the key to POR15 is to be able to get out as much of the excess as possible once the tank is completely coated. The tanks where I've seen the worst bubbling were the ones that had the most excess goo remaining in the tank during the drying process.

Also, did you use the chain & Marine Clean and do the required sloshing procedure, and then use Metal Ready?

- Doug

Mon Aug 19, 2013 9:49 am

skills@eurocarsplus wrote:
since then, i have parted out a bus that had this red shit in the tank, looked like a candy apple coating. that tank too is pulling away.

:? I just bought 2 quarts of Red Kote. I read almost no complaints here and in the American muscle forums. I was going to do this this afternoon. Now I'm second guessing myself. I did the muriatic acid wash and the tank is pretty clean.
The Red Kote instructions say to allow all excess product to drain out of the tank as the excess will bubble and peel if it is too thick. :-k

Mon Aug 19, 2013 9:58 am

Just washing your tank with water, and pouring it out, should give you an idea as to how much will be inextractable when drip-drying...this was the case with some motorcycle tanks I coated with POR15...the filler neck protruded down into the tank a bit and when letting the POR15 drip out (tank upside down) there was some liquid that couldn't exit, and pooled inside. That said, I haven't had a lick of trouble with that tank despite some bubbling where the goo pooled.

I was planning on coating the inside of my '75's tank next month using POR15...in this vintage tank is it pretty easy to get out as much of the excess coating as possible (via drip draining, before it dries), or are there protrusions or pockets where the goo will pool?

Mon Aug 19, 2013 10:26 am

I did the chain washed it out, muratic acid bath, marine clean, another muratic acid bath, then the metal ready, then sealed it and let it sit for a week. For the first 4 or 5 days it looked great there were some minor bubbles on the surface but those didn't concearn me. All of a sudden the bottom half of the tank began coming off in sheets with the little bubbles still intact on the surface. It appears that the bottom is going to come off on its own up to the seam around the middle of the tank. Above that seam looks to be holding fast unfortunately, hope it just keeps sheeting off and get outta my tank!!

Mon Aug 19, 2013 10:42 am

Quote: Works in the short run, but long-term, it's not going to really do a whole lot.

Not the concept of why ATF is used - The ATF keeps the rust away until you fill the tank. Keeping clean fuel in the tank will keep rust away although the higher the percentage of alcohol or MTBE in the fuel the higher the Oxygen levels in the fuel. Pure gasoline has little Oxygen in it. Tanks rust because often water gets in the fuel and the O2 in the water gets in contact with the FE and forms rust. That or the tank is run low all the time and humidity and oxygen in the air get to it.

Liners are a crap shoot. They work out for some folks and don't for others.

Mon Aug 19, 2013 10:50 am

busdaddy wrote: guitarman63mm wrote: I will never understand why people use muriatic acid. Hydrogen chloride gas is one of the most corrosive gases in existence - the moment you remove rust in one spot, you're creating it in another.

Because it gets the rust out in a hurry and it's cheap and easy to use, TSP is a strong base and neutralizes it if you are lazy on the rinsing but I like the phosphate treatment right after myself followed by a drying and oiling.

Any better options you can suggest for home use?

I use electrolysis to remove the rust and paint on all my parts, followed by an acid etch for 20 minutes or so with ospho to remove loose iron and any residual rust. Then I wire brush and rinse it off, hand dry with a towel, and toss it in the oven at 175 or hit it with a heat gun for a few moments. This is time-consuming, but I hate rust.

Knowledgeable motorcyclists use electrolysis to clean their tanks. It's easier on that because you can just stick a piece of rebar with some pipe foam around it right into the tank, where as we have awkward curves and a much larger volume, but when I get around to doing my tanks, I'm doing the electrolysis + phosphoric acid treatment.

Mon Aug 19, 2013 11:14 am

I had these guy do it for me (the local radiator shop shipped it to canada to have it done though).

http://www.gastankrenu.com/index.htm

Mon Aug 26, 2013 2:07 pm

Ahhh it's slow goin.... But it's goin. Aircraft stripper with methelyne chloride is buy far the most effective, not as effective as I would like but I think I can get this crap out!💩

Mon Aug 26, 2013 7:32 pm

Mr. Unpopular wrote: I got a sweet old Dodge K-car from a friends mom who barely drove it. Since she barely drove it, she barely put more than a gallon or two of gas in it. The top 3/4 of the tank was rusty because it never got washed in gas.

I did the muratic acid and chain bit, then filled it with gas, and keep filling it with gas when it's low. No issues.

Same with our bay tank. I was scared to use the POR15 because I heard it doesn't like the new E10 gas we are forced to live with. So I keep it full and don't have issues.

Oh, and get a fuel filter from an early 90's 300zx. It's big, metal, and has 5/16" in/out.

^This. With every bus I get I do an acid clean then pop it back in and drive it daily. Just had the tank out of my 79 after doing this some 9 years ago and it was absolutely spotless inside. Buses like to be driven.

Mon Aug 26, 2013 7:45 pm

Actually, taking out the tank on a Beetle is so easy I wouldn't hesitate in the future to just take it out and have it cleaned by a radiator shop when it gets too rusty. But I understand it's harder to take it out on a bus.

Mon Aug 26, 2013 7:55 pm

I just used evaporust on my ghia's gas tank, I rotated it every few hours. I then washed it out and dried it with compressed air, I then coated it with master coat. I let it sit for three days. We shall see how it goes but if it starts peeling I'll be buying a new one:(

Mon Sep 02, 2013 9:45 am

Well everyone, I'm sad to say I threw in the towel! I just couldn't waste anymore time on a tank I still can't use. I just ordered a used one from interstate vw. I hope it's overall condition is as nice as the one I have, we shall see. I'm going to make a witches brew for the current one to soak in and I'll let you know the results. Watch that POR-15 sealer if it goes bad its REALLY BAD!!