Gas Tank Rust

[Crossrodes]

Bad news.  

I flushed my gas tank with water a few weeks ago (got all the water out and dried it) and then proceeded to prepare to paint the tank and other parts.  During that process I was doing a lot of wet sanding.  I had plugged the tank to prevent water from getting in but damp vapor got in anyway.  I noticed at one point that the inside of the tank was damp so I dried it out.  Well now that the painting is completed (looks great by the way) I decided to stick a flashlight in the tank to see if any rust had formed and yes it has.  There are little rusty lesions in the tank.  So I'm guessing that the coating was marginal.

I know there was a posting recently on flushing the tank and re-coating and went looking but could not find it.  So here are the questions:

1. What product is recommended to clean the tank and remove all the factory coating.  Is the procedure included in the product packaging?

2. What product is recommended to re-coat the tank? Same question re the procedure?

3. What is used to seal the tank before the products are poured in?  I'm assuming that the petcock is left out.

4. Are there any hidden vent holes that I need to protect so that the tank will operate correctly after re-coating?

5. Are there any other precautions or procedures I should be aware of?

[Rob Valdez 79 R65]

Vinegar to remove the original red lining.

I think I would go with POR-15 for a relining product.  
It would appear they have more than one kit, and I am not sure which to recommend, as I've never done this.
http://www.por15.com/Fuel-System-Restoration/products/12/

Since I've never done it, I am not much help on the rest.  But there are plenty of folks here that can.

[Crossrodes]

Thanks Rob.  Do you know if the vinegar will get rid of the rust also?

[Rob Valdez 79 R65]

I doubt it.  But the etcher in one of the kits would probably do it.

http://www.por15.com/PREP-READY/productinfo/MRG/

[Crossrodes]

Thanks Rob.  The etching looks good.  Now the question is how much?  Maybe someone who has done this will chime in.

[Rob Valdez 79 R65]

Well, they sell the coating in pints and quarts.  I'd be willing to bet (not too much!) that a pint would do it.

I don't know where everyone is, tonight!

http://www.por15.com/POR-15/productinfo/1GB/

[Bob_Roller]

I went through this process about a year ago .

I had a fuel tank from an '84 LS, the interior of the tank looked like an old exhaust system off of a four wheeler .

I got a POR 15 motorcycle kit and tried it .

The first component is a 'sludge' remover, the quart bottle had the contents that looked like it was a sodium hydroxide solution, common drain cleaner .

I tried it and it did some good, but not nearly good enough .

The second bottle had some sort of acid solution, again in my instance, it didn't really do any good .

I had heard of using molasses in water, sounded a bit out there, but I tried it .

To make the story short, molasses in water 'ferments' into a compound that contains acetic acid, the acid that is in vinegar .

I have to admit, it did a great job of removing the rust and remaining liner in the tank .

I have no idea what acid concentration the solution had .

If I were to try it again, I think I would try generic white vinegar and see what happens, with the average acid concentration of 4-5 % in retail vinegar, it may take a bit longer to remove the rust and liner .

A couple of members have used muriatic acid with good results .

You can get 35 % muriatic acid for use as a ph reducer for pool use, I don't know if it is widely available in your area or not .

The sealant in the POR 15 kit comes in an 8 fluid ounce, or 237 ml can, more than enough to do one R65 fuel tank .

When I try this again with the fuel tank from the Guzzi, I'm going to just use vinegar, and get the smallest can of liner material I can get, as the POR 15 motorcycle kit, at least in my case really didn't do the job.

[Crossrodes]

Thanks Bob.  I think I'll try the vinegar.  I'm assuming I will have to turn the tank every half hour or so to get the vinegar working in every nook and cranny.  Any idea how long I should leave it in the tank?

Right now I'm experimenting with some vinegar in a small bowl and some saran wrap.  I'm thinking that if I put the saran wrap over my gas tank stopper it will stop the vinegar from leaking out the vent in the cap (I'm assuming there is a vent in the cap).  I'm also thinking of making some kind of a stopper for the pipe leading to the carbs and wrapping that with saran wrap.  Any thoughts on that?  Also I'm thinking there is no other vent...am I right?    

[Rob Valdez 79 R65]

There is a vent in the cap, I think.  
The overflow inlet is located at the top of the tank, part of the cap opening, I believe.  See the outlet located on the bottom of the tank?  Just follow that up to the top and you should see it.

I just used white vinegar for the first time to clean the lime scale off of my bathroom shower head.  Since I have a removable WaterPic, I just took it off and put the whole thing in a 1 gallon plastic zip-lock bag and let it soak for about 8 hours.  I found out some have really small holes in them!

I had always assumed one would just pour 5 gallons of vinegar into the tank and let it do it's thing.  Hopefully a rubber stopper in the petcock hole would be enough, but it would have to be a GOOD fit.

And then, of course, you have the mess to clean up, afterward.  Too bad you painted the tank, first.  The best way to go about this is to take it to a radiator repair shop and have them "dip" the tank.

[Bob_Roller]

I used rubber stoppers in all of the holes in the tank, I removed the fuel tap as well .

I completely filled the tank when I did this process .

The tank needs some sort of vent, as during the rust removal process, gasses are released, so don't completely seal the tank .

I'm not certain, but I think vinegar may very well stain the paint if it gets on a freshly painted surface .

[Crossrodes]

Bob I'm not sure I can find a rubber stopper to fit the gas cap.  So my question is because I need a vent why not just leave the gas cap in.  Also why not leave the fuel tap in...would it get damaged by the vinegar?

I've thought about the new paint getting damaged and I'm thinking I'll have to be really careful.  I'm also thinking of "almost" filling the tank with vinegar on the first go round and then having a second go round with vinegar but inverting the tank this time so that the coating on the inside top of the tank gets cleaned off.  I've done a little experiment with saran wrap in a bowl overnight to see if the vinegar would burn through it...it did not.  So I'm thinking on the second vinegar treatment to put saran wrap over the the fuel cap to stop the vinegar from leaking through the vent in the cap when the tank is inverted....any thoughts on this method?

I used to use muriatic acid in my boat to clear sewage hoses and I've used it to etch concrete.  That is rally nasty stuff.  It would certainly do the job but I think I'll stay away from it unless I need it.

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[Bob_Roller]

I tried cleaning up a fuel tap using 9% acid content vinegar, there was rust on the threads .

After 30 minutes, I saw the acid was attacking the zinc or whatever plating is on the steel parts .

The aluminum wasn't any happier, it had turned almost black .

I personally wouldn't expose the fuel tap to vinegar .

You need to get the top of the fuel tank clean down to bare metal, or there is the possibility of the lining material you use, may not adhere to the remaining OEM liner .

Large rubber stoppers are available at home brewing and wine supply stores, that's where I got mine, don't know if you have any nearby or not .

[Crossrodes]

Thanks Bob.  I'll try my winery.

[Lucky_Lou]

I seem to recall a similar thread a while ago where Coke (or Pepsi) was used to good effect,, better than drinking it anyway.
Lou

[Bob_Roller]

Look at a container of Coke, it contains phosphoric acid .

Lou, thanks for bringing this up, as it is another effective way to clean out a tank .

I forgot to mention phosphoric acid, it will work, but it's around $12US per gallon and it's useless after using it for this .

It's a good etching solution after using some other acid or substance to clean up a fuel tank interior .