cleaning gas tanks

If it's rusty, you'll need to rinse it, clean it, pickle it (also known as chemical etching) and then seal it - or - if you can find someone who has a tank tumbler - you can just put some aquarium gravel and water into the tank and let it roll around for a couple of days to clean it. Some people even use roofing nails or ball bearings and water in the tank instead of gravel. BTW - the tank tumbler is a machine which rotates the tank around all three axes at once (think - portable cement mixer). The action is slow and fairly gentle but two days of that motion, along with a couple of rinses, and the tank will be shiny and clean inside.

During this past fall, I did that tumbler routine with my XS750 tank for my cafe build (see the thread '81 Special to cafe build" - there is a video of the machine working and it did an excellent job. Once it was clean, I just sprayed in a little WD40 and sealed it up with the petcock and the fuel filler cap. Once I start to use it the tank should stay clean as long as I keep fresh fuel in it.

Last winter, prior to finding the local chap who had built his own tank tumbler, I had a rusty tank on my '76 Standard after it had sat empty for a long time. I did a fair bit of research and I found that the best stuff to clean and seal a rusty tank is called POR15.

A lot of the bike shops around here used an older chemical treatment called KREME - but apparently it can be dissolved by the ethanol which is added to many brands of gasoline these days and so it will eventually flake off and clog up your fuel system. If you look around, you'll find that a lot of people have had very unhappy experiences with KREME - but POR15 seems to have a very good reputation.

I would suggest that you check out the POR15 website - it is the same stuff that Jay Leno uses on all of his big-dollar vintage cars and he did a very convincing testimonial on the POR website for them. You can get a POR15 motorcycle tank cleaning and sealing kit that includes all of the necessary stuff and it did a superb job on my '76 tank. One of our local autoparts places sells the kit for around $70 I think, although I got my kit on-line.

A couple of things to note about using POR15:
- sealing the fuel filler hole and petcocks holes is not easy. I found that no type of tape would do it. I used a rubber bung (like a cork) from a wine making store in the filler neck and I made a couple of patches out of old hotel plastic keys (sort of like credit cards) for the petcock holes and I simply fastened them onto the tank with the petcock screws.
- the chemicals you'll be using are pretty strong so follow the instructions to the letter and don't spill them on anything you care about - particularly the sealant which is a silvery liquid about the viscosity of maple syrup. It is impervious to any type of paint thinner or stripper.

Personally, I liked the tank tumbler method because there were no nasty chemicals and now that I know a local guy who has one, I'll always use it for dealing with an old fuel tank (assuming my wife ever lets me buy another old bike that is). However, I was perfectly satisfied with the job that POR15 did on my '76 XS650C fuel tank, so I wouldn't hesitate to use it if you don't have a tank tumbler handy.

Which ever method you use, it is obviously important to ensure that the fuel in your tank stays clean and that no crud gets down those little hoses into the carbs. Once you get it cleaned out - keep the darned thing full of clean fuel and use it so that the fuel doesn't go skunky and cause problems in the future.

Cheers,

Pete
 
I like the real simple way of filling it up with vinegar and letting it sit for a few days. Depending on how bad it is, you could cut a couple 8 or 10 inch pieces of jack chain and swirl them around with a bit of vinegar to get the big chunks of rust out, then rinse out and refill with vinegar and let it sit for 2 or 3 days, giving it a little shake once in a while.
Once you are ok with those results, dump it out and put a litre or so of metal rescue in and let it bath all sides of the tank so it will treat the clean inside, or you will have a case of flash rust that you will not believe.
I have done the electrolysis method and it works well too, plus you are using science, but the vinegar keeps it simple and works just as well.
 
I have done vinegar in 2 tanks and it worked really well!

- Take tank off bike
- Cut up old innertube and use a piece to seal off the opening where the petcock goes. Pull out the straw and only cut holes for the screws, not the middle or your petcock will melt.
- Put a piece of 2x4 under the rear end of the tank, this will tilt it so that you can fill it up completely
- Put 3 or so gallons of vinegar into tank
- Check on it every few days.


After a week or so I dumped maybe a 1/3 of vinegar out and then shook the hell out of it and dumped the rest - TONS of rust came with it.

I then rinsed it with a garden hose and IMMEDIATELY poured in a bottle of 3/4 2-stroke oil and 1/4 gasoline and sloshed it around to prevent the tank from flash rusting.

I'm using one of the tanks on my bike right now.
 
I would suggest that you avoid nails or drywall screws or gravel or aquarium gravel or loose diamonds as you have to get them out and there is quite a lip under the filler neck and the petcock openings are small enough to discourage vigorous flushing. Throw a chunk or two of chain in there, and if you cannot reach it after with your finger, a coathanger with a hook on it will get it out.
 
Yes, for sure white vinegar, some misguided back to nature folks will say cider vinegar as it is more natural, but its already opaque brown so you can't see it working and what you need is a 5% solution of acetic acid, period. I have bought the cheap stuff at the dollar store, but it seemed a bit slower to work than the no label brand at the supermarket.
Incidentally, I have found rubbing alcohol for rinsing at the dollar store way cheaper than a drug store and bigger quantity, too.
 
I just did 2 tanks recently that were rusty. One had a sealer in it that had failed, so I had to get that out first...but then I only used evaporust (Got it at Harbor Freight and found it online for a little less). This stuff is pretty amazing, non-toxic, and super easy. I've been using it to refurb my latest project and all nuts/bolts, chrome bits, etc. come out looking great (a little greyish depending on the type of metal, but clean up great). This method is similar to the vinegar concept (albeit more expensive but faster)... Anyways, pour it into your tank, leave it for a day, pour it out (save it as it can be reused until it's dark brown/black), rinse and your done. Depending on how much rust we're talking...you could leave it for a few days. Once you rinse, you'll want to fill it up with gas or coat it (2 stroke oil) to limit flash rusting.

In the tank that had sealer in it, I got that out using nasty chemicals...with a handful of metal nuts to get the walls cleaned. (Use a magnet to get them out later if needed). I avoid sealer if at all possible. I know it is and can been done successfully (I do have a tank that I picked up where the sealer is still perfectly solid) but more often than not, most of the tanks I seem to pick up that have had it done have failed.

Good luck!
 
I have used evorust on two tanks. Filled them up, slosh around in the morn, slosh around befor bed for a week. Shiny!!
 
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You can buy this rust cutting media in a 5 lb container at Harbor Freight. Strips the rust and won't cut the good metal. I did it in the dryer. I put the tank in an old sleeping bag and stuffed it full of pillows. Do I have to say run the dryer with the heat off?

I'm afraid the electrolysis method may cause hydrogen embrittlement and weaken the metal. Vinegar of phosphoric acid work well, but etch good metal. It has worked well for me.

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This is good, so is Evaporust (I've been told). Metal Rescue was what I used.


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This is the stuff to seal it up!
 
My vote, the cheapest and easiest is vinegar. I follow the vinegar with a quick water rinse, then rubbing alcohol to dry and Red Kote to line.
Not only will Red Kote line to prevent future rust it will seal small pin holes and ethanol isn't a problem. I've got a 10 year old lining on the F model no worries.
There are some pictures on the site somewhere that show the pin hole seepage on a D tank. It was lined and two weeks later ridden 1800+ miles in 7 days.
I just took it to work day yesterday, still no problems.
 
Lots of useful ideas here - and it sounds like they all work!

I did note that nobody was an advocate of KREME - which all that the shops around here wanted to use.

Pete
 
I guess I've lucked out,
none of the tanks I've ever had to deal with needed their insides de-rusted.
But if I ever had it to do I'd use a mechanical abrasive that I could fish out with a magnet then a propriatory jollop like metal rescue.
And of all the posts I've ever seen about Kreem, I've never seen one that liked it.
 
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