A good friend of mine has a 1996 Harley Dyna, and it's been sitting for the last 6 years with about 1/4 tank of fuel. He went in for bypass surgery late last year, and I trailed it home and told him I'd get it running. Just one of the many things to be dealt with was the gas tank.

In 96, HD installed an epoxy coating in the tank. As I've read, and read, and read, apparently they are known to fail. I bought 5 gallons of white vinager, and filled the tank for about two weeks. Much to my surprise, as I drained the vinegar, I found that 95% of the liner came free. Maybe 98%.

Of course, after flushing the tank, it flash rusted pretty badly almost immediately. I dumped a 1/2 pound of baking soda in (twice) and flushed it out twice. No bid deal, I thought, I have a plan. If I've read once, Ive read a hundred times to just throw a handful of nuts, bolts, and drywall screws in there and dance around a while. That didn't sound any fun to me. So, I went to Home Depot and bought a bag of sand. Not play sand, sand from the concrete aisle.

After spending a lot of time trying to get the tank absolutely dry, which I eventually accomplished with a hair dryer, I poured 1.5 gallons of sand into the tank. I then dug out an old king size comforter, about 6 old pillows, and my box car wash towels. I put the comforter in my dryer, followed by the gas tank, pillows, etc. Long story short, the tank ended up jammed in the middle of the dryer drum with no room to move and damage (or be damaged). I turned the heat off, and tumbled the tank for an hour. Stop. rotate the tank 90 degrees, repeat. 4 cycles altogether.

Upon removal, I was ecstatic with the results. The tank has a pretty large hole for the fuel guage/sender, in addition to the fill point, so I can see in there pretty well. 90% of the rust was gone, and most of the tank appeared to be bead blasted. I did notice though, after draining the sand out, that quite a bit of 'sand' was stuck to the walls. I decided that maybe the bag of sand I bought had some moisture in it. And there were just a few areas of very light rust color that hadn't disappeared yet. I also believe the hump in the tank reduces the effeciency of how the media rolls around in there.

No worries, I thought. I dumped a bottle of 6000 bb's in there, as well as a large handful of 1" drywall screws last night, and sent it on it's journey in my Whirlpool Media Tumbler again.

Now, imagine if flour was tan in color. No imagine using it to bread a chicken breast before frying. That's what the inside of the tank now looks like. Its a thick chalky residue, for lack of a better term, absolutely stuck to 100% of the tank interior. Of course the bb's and screws were also coated, so I pulled a handful of them out and headed to the sink. They rinsed clean without much effort, which is a good thing.

What's not a good thing, is that I don't want to fill that damn tank with water again. I anticipated the sand just falling out, and I was going to rinse with OSPHO (a product based on phosphorus acid) that would have absoluted killed any rust living in the pores and left a rust resistant coating.

I'm tempted to toss a quart of lacquer thinner in there and splash it around, but I know from experience that LT does nothing for dirt. Nothings better for oil, but dirt has always laughed at it in my endeavors.

Now, I'm sure that I can rinse with soap and water, rust it up again, and retumble with a better choice of media, but I can't stop trying to think of the best way to not have to do it all over again.

Any cleaning suggestions would be appreciated.

A few pics forthcoming...

Not sure if this would help or hurt in your case but years ago I was rebuilding an old Honda with a dirty, rusted and generally neglected gas tank....best advice I got was from an old guy at the machine shop where I took the head and cylinders.

He told me to dump some gravel in the tank and then a couple quarts of marvel mystery oil then shake it up for a few days, drain the mess and then flush with clean mystery oil. He also suggested soaking an old bed sheet and leaving inside until I was ready to fill with gas....it worked like a charm

Brake Cleaner perhaps? Doesn't leave a residue.

Carb cleaner? Will eat off about anything. Comes in gallon cans. Not sure about how much if any residue it leaves. May have to follow with brake cleaner to remove any residue left by the carb cleaner.

Thanks, Kevmo. I was planning to coat the walls with two stroke oil after the OSPHO treatment, but I had forgotten about Marvey Mystery Oil. The bed sheet is a great idea as well.

I don't know a lot about chemistry, but I've since read that excessive 'base' can be as detrimental as too much acid. I'm worried I over did it with all the baking soda, and I can't help but to fret if that caused or contributed to my residue problem.

I had good luck with evapo-rust. I used it to clean a Honda gas tank that sat with fuel for a few years. It did wonders on cleaning out the crud without hurting the tank.

I top off my tank after every ride but I’m OCD about avoiding rust/issues with my bikes. It’s been looking good inside the tank for 4+ years since I had to give it that thorough cleaning.

If the BBs and screws rinsed off easily with just running waster what about using gas to rinse the tank?

quote:

Originally posted by SpinZone:
If the BBs and screws rinsed off easily with just running waster what about using gas to rinse the tank?

Great call, SpinZone. I guess I was looking so hard for a complicated answer, I neglected the easy one. I'll try this next.

quote:

Originally posted by stickman428:
I had good luck with evapo-rust....

This is your answer. (and you may have to use soap and water to get all the sand out)

Evapo-rust will only chelate the iron oxide, not iron or steel.

After that is done, pour in the ospho and get it all coated, then pour out and follow up with reducer or Prep-all, and then force air dry.

Then you should be able to use a internal coating if you desire.

Thanks, Monkey and Stickman.

If the sand/dust insists on soap water, what do you think is the best detergent? Dawn? Simple Green? Purple Power?

As far as a coating, I believe I've decided against it, at least for now. I've read extensively about peoples experience with POR15, Red Kote, and Kream, and it seems there's as many failures as there are long term success stories. Heck, even Harley's version failed. (but to be fair, it is 22 years old and neglected)

My thought is that we ran around with bare steel tanks for years without problems, so far as the equipment was used and reasonably taken care of.

On the other hand though, it may well be that those folks just didn't do a good enough job at the prep. I did find a product yesterday by Caswell Plating that's marketed to repair POR 15 and Kream failed liners. Which really just pushed me even further away from the concept. I do think though, that if I were to be talked into a liner, I'd go with the Caswell.

To explain that just one step further, if the tank was truly round or square, I'd have more confidence. But with that huge hump in the middle, I don't know how hard it will be to roll it such that the coating is everywhere- and I wont be able to see it, to boot.

Keep in mind that todays fuels have ethanol in them and ethanol is a water magnet whereas in the old days we had unadulterated leaded fuel.

You could get one of those little snake-like inspection cameras (bore scope) used to inspect cylinders and such - they have gotten cheaper. They also make some USB versions that connect to the phone and use the phones camera.

I have a good friend that owns a Harley/Motorcycle Independent shop he's done this for different people so I asked his advice.

1) don't coat the tank inside, you should be fine if you have all of the liner and old rust out, it's a 96 dyna not worth a ton of money and should be fine.

2) If you are concerned with doing that, find a radiator shop, they can coat the inside with Red Cote, and you'll be done, few hundred bucks probably at the most

3) Buy 5 gallons of Metal Rescue, it's the stuff that will seal off the bare metal and kill off any rust, you pour it into the tank all 5 gallons and let it sit overnight, drain it back into the original container and you can use it again, sell it to a shop etc. It will seal any left over rust up and the bare metal.

4) If you want it lined get a pro, GTL in Hollywood CA is where he sends tanks for a liner and says they are top notch, and expensive Probably $400 to $500.

Link to GTL

Me, I'd drain it clean it out and run with it..

You want Damon Red-Kote.

Evapo-Rust is the right approach.