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Sun Sep 18, 2016 9:56 pm

bus68us wrote:

Your tank definitely does not need to be resealed. I'd roll with it after your second wash and just keep an eye on the filter.

Wed Dec 07, 2016 5:20 pm

Just a quick update for you guys since it's been awhile and about 1500 miles since completing this job.

I'm happy to report that my tank and fuel system is doing great. Since restoring the tank the bus runs better, starts the first try (it took a few tries before) and seems overall "happier". I'm guessing with all the rust that was in there it was starving for gas. I solved a number of issues just by doing this one job that happened to be a little bit of a PITA.

BTW, replaced on my fuel lines and my engine seal while I had everything apart. Found out PO had SAE fuel hose installed. Dodged a big bullet here for sure.

Thanks to everyone for the help, she ran great out to San Diego and back.. :D

Thu Dec 08, 2016 11:13 am

One of the steps I was told and used in the muratic acid process was to dump a gallon of white vinegar in the tank after a rinse to neutralize the acid. That seemed to minimize the flash rust.

I did that in my bug which had sat for 7 years in San Diego empty tank and just rusting more each day. Before I did the acid, soapy water, vinegar process my filters would be rust red in days and clog each week. It's now been 5 years of no issues.

Thu Dec 08, 2016 1:53 pm

bus68us wrote: Here's what my tank looks like after 2 muriatic acid washes of 1 hour each and a phosphoric acid wash. Did I do something wrong or is it supposed to get flash rust after ospho?
That looks like it has flash rust after the hydrochloric acid (aka muriatic acid, for some reason) wash. With that bit of flash rust in there, it is perfectly ready to hit with Ospho (which has phosphoric acid in it, but is not the same as generic cheap phosphoric acid -- don't cheap out) to turn that nice thin layer of iron oxide into iron phosphate. Go back and read Ray Greenwood's bit on why you need a thin layer of iron oxide in order for the Ospho to work.

After the Ospho has had a chance to do its thing (let it dry well, like a day or two), the rust color should turn a dark brown or black. Then you hit it with a coating of mineral oil or ATF or thin motor oil just to keep it happy until it gets back into service.

At least that is my take on it, after reading this entire thread.

Thu Dec 08, 2016 5:43 pm

Ive used this https://www.kbs-coatings.com/ and havent had any issues. Its been atleast 4 yrs now.
ymmv

Tue Jan 24, 2017 8:59 am

Anyone use cider, not white vinegar? Saw it on YouTube.

Think I could get away w/o coating the inside of the tank?

Tue Jan 24, 2017 10:17 am

Don't seal that unless there's a hole in it, have a look at this: http://www.thesamba.com/vw/forum/viewtopic.php?t=378770

Tue Oct 10, 2017 5:38 pm

My tank is about the same condition as the above tank, maybe a little better. I dropped it off to have it acid cleaned at a shop that does fuel tanks. From what I see here I am not going to coat it with anything after getting it back? I didn't have any leaks either but I want to do this right before putting a new performance engine in. Does the acid wash remove a coating so now that I have it cleaned will it start to rust?

Also from what I read I will also remove my internal filter screen and just use the washer. Nothing else to seal the hose connection from what I see.

I will research my filters, I currently have a Carter (CB) fuel pump with a filter and 1 clear filter before... maybe too many. Either way I would like one quality filter before the pump.

74 Westy

Tue Oct 10, 2017 5:59 pm

jacoby1007 wrote: My tank is about the same condition as the above tank, maybe a little better. I dropped it off to have it acid cleaned at a shop that does fuel tanks. From what I see here I am not going to coat it with anything after getting it back? I didn't have any leaks either but I want to do this right before putting a new performance engine in. Does the acid wash remove a coating so now that I have it cleaned will it start to rust?

Also from what I read I will also remove my internal filter screen and just use the washer. Nothing else to seal the hose connection from what I see.

I will research my filters, I currently have a Carter (CB) fuel pump with a filter and 1 clear filter before... maybe too many. Either way I would like one quality filter before the pump.

74 Westy
Your filter ideas sound fine.
The screen is also the seal so you can't just leave it out, if you are concerned poke it full of holes or tear it off that aluminum washer and use that washer (that's the seal). I like the screen myself, if the fuel and tank are clean it's never going to clog up, if it does you can stab it with a piece of wire through the outlet nipple and be back on the road in minutes.

The tank isn't coated with anything when new, not even galvanized, slosh a cup full of ATF aroound in there to coat it until you put gas in and call it done, if the gas stays fresh and dry later in use it will never rust.

Tue Oct 10, 2017 6:07 pm

Thanks! I just got the new screen filter and will keep it, even the OG one I had was not even clogged. Glad to hear the tanks didn't have anything in them originally. I also drive this daily and it doesn't sit much. First time I bought ATF in a while!

[/quote]
Your filter ideas sound fine.
The screen is also the seal so you can't just leave it out, if you are concerned poke it full of holes or tear it off that aluminum washer and use that washer (that's the seal). I like the screen myself, if the fuel and tank are clean it's never going to clog up, if it does you can stab it with a piece of wire through the outlet nipple and be back on the road in minutes.

The tank isn't coated with anything when new, not even galvanized, slosh a cup full of ATF aroound in there to coat it until you put gas in and call it done, if the gas stays fresh and dry later in use it will never rust.[/quote]

Tue Oct 10, 2017 6:32 pm

Anything oily will work to coat it for storage, ATF is thin and leaves a film, motor oil or gear oil will too (might want to thin that with solvent first), or 1/2 a can of WD40 will even work as long as you slosh it around to coat the entire inside, drain off what's left and the residue will protect the metal until the gas washes it off and it gets burnt in with the first tankfull.

Tue Oct 10, 2017 6:45 pm

Also you don't think I will have any issues with the left over ATF residue on my new engine? I am guessing the amount is so small it doesn't matter?

busdaddy wrote: Anything oily will work to coat it for storage, ATF is thin and leaves a film, motor oil or gear oil will too (might want to thin that with solvent first), or 1/2 a can of WD40 will even work as long as you slosh it around to coat the entire inside, drain off what's left and the residue will protect the metal until the gas washes it off and it gets burnt in with the first tankfull.

Tue Oct 10, 2017 7:20 pm

jacoby1007 wrote: Also you don't think I will have any issues with the left over ATF residue on my new engine? I am guessing the amount is so small it doesn't matter?

busdaddy wrote: Anything oily will work to coat it for storage, ATF is thin and leaves a film, motor oil or gear oil will too (might want to thin that with solvent first), or 1/2 a can of WD40 will even work as long as you slosh it around to coat the entire inside, drain off what's left and the residue will protect the metal until the gas washes it off and it gets burnt in with the first tankfull.
Well of course you will stand it up in a corner and let the excess accumulate so you can dump out as much as possible, but a few spoonfulls missed won't make any difference or hurt your new engine in any way, consider it an added dose of top cylinder lubricant.

Sat Jan 30, 2021 5:44 pm

Hey guys,

So this weekend I finally pulled my fuel tank out.

It was pretty bad, basically the bottom half covered in rust. I did what was suggested. Muriatic acid 1:1 with water. Rinse with baking soda. Then I used fan to dry it quickly. Once that was done i poured some rust converter (phosphoric acid) into the tank. Will let dry over night. Tomorrow I will be pouring ATF in there.

I am very happy with the result. With the one exception.....my tank is now pink inside, like it was made out of copper. Is this normal? Did everybody else end up with pink tank after using phosphoric acid?

Thanks!

Sun Jan 31, 2021 2:09 pm

This is what I came to today. I am so dissapointed. After muriatic the tank was like brand new inside. Nice silver color. This is what the rust convertor did. I am not liking it at all

Sun Jan 31, 2021 3:04 pm

Too fast.

You do NOT want to dry the tank quickly after using muriatic acid. The object is to let is flash rust. It needs to have a nice even layer of DRY surface flash rust.

Which phosphoric acid product did you use?

You have to pay attention to the solution strength and what the product description is.

For example...in the past....Jasco metal prep and prime was my go to product (no longer made now). But....straight from the container....it is far too strong and will remove all rust and leave nothing to convert. Its directions note that for rust removal....use straight from teh container. For rust conversion....dilute it with water 2.5X to 1.

Also a lot of phosphoric acid based products have a surface coating polymer mixed in. That may be what you are seeing. Ray

Sun Jan 31, 2021 3:33 pm

Product i used is called Pro-Form rust comvertor. According to data sheet it contains 10-30% of phosphoric acid, isopropyl alcohol and cupric sulfate. It says fo not dilute and must be topcoated. Let dry for 24 hours.

Its pickle. What to do now? Repeat the while proces and hope it will deal with this brownes?

I would need to find something else obviously for conversion. And when you dilute phosphoric, you just use water?

Sun Jan 31, 2021 4:50 pm

You can try some Phosphoric and see what it does to that golden brownishess, if not a quick Muriatic wash will get it off. As Ray mentions a fine layer of orange after it dries from rinsing out the Muriatic makes the Phosphoric work better. Don't do more than 2 hours with the Phosphoric and dry it quick after rinsing that stuff out, a leaf blower works great for that.

Sun Jan 31, 2021 5:01 pm

busdaddy wrote: You can try some Phosphoric and see what it does to that golden brownishess, if not a quick Muriatic wash will get it off. As Ray mentions a fine layer of orange after it dries from rinsing out the Muriatic makes the Phosphoric work better. Don't do more than 2 hours with the Phosphoric and dry it quick after rinsing that stuff out, a leaf blower works great for that.

Thanks Mark, I will follow your recommendations. There is couple things I am no too sure about...

1.I will source the product you recommended, I have a shop not too far from me but they were not open on the weekend. But for that, do you use the phosphoric straight out of bottle or do you dilute it?
2.One of my mistakes I guess I left it there for 24 hours which was recommended on the bottle so I will definitely cut the time to 2 hours. Shop vac works magic for me for drying. When you say after rinsing that stuff out, you mean after two hours of Phosphoric, rinse with water? Or?

Also I will just sum thing up,
Muriatic Acid for 15-30 minutes
-) empty tank -) pour water with baking soda to neutralize the Muriatic -) let dry enough to create slight rust film -) Phosphoric Acid in the tank for 2 hours -) empty tank and rinse with water and use shop vac to dry quickly -) ATF because It will be sitting empty for a bit

Sun Jan 31, 2021 5:24 pm

I did one last week, repeated Muriatic soaks until clean, followed with a water rinse (no baking soda, no drying), next day a cup of hydroponic supply PH down (80% Phosphoric) into the cup or so of water that was still in the tank, roll around the yard an hour or two then drain and rinse with water. Then force dried immediately and finished with ~1/2 cup of ATF.
Since you have already gotten the big scale off it shouldn't take long with the Muriatic to get it bright inside again, the stuff in there now doesn't look heavy.