A project that I laid aside was to take my third gas tank (the one from the parts bike) and buff it out so it was very shiny. Didn't work. Primarily because the tank had been dinged a few times and the dings were near impossible to take out. So now I've decided that I can use it as a spare to work on while I continue to ride the Silver. Its tank has blemishes and a few scratches so fix this spare and eventually use it as a replacement.

But my question has two parts 1.) is how to remove crud from the inside and 2.) how to remove glue etc from the bottom of the tank.

Inside the tank there appear to be small bits of discoloration. Looking very much like iron rust. But of course the tank is aluminum. I sealed everything up that I could reach, dumped in a half lb. of lead shot and shook until I felt very much like a paint shaking machine. Removed the shot and some odd bits of trash. But the discolorations remain. Tried a cloth on the end of a long screw driver and could get some of the crud off but not all. Are there any compounds suitable to clean the inside of a gas tank?

The bottom of the tank has glue from the heat shielding still clinging to the metal and some just crud. I tried "Ooops" and got a good deal of the glue off. But it looks like another application or two are going to be needed. But I've been using straight gasoline to help aid in removing the glue and any dirt crud still clinging to the metal.

Any suggestions on cleaning preparatory to bondo and repainting the tank?

This all came about because the weather was quite nice today, 71F outside, and I got started on redoing the tank while the weather holds.

ScotchBrite pushed around with a stick does a pretty good job of scrubbing the inside of a tank Throw a quart of vinegar in and let it sit for a day or two and then go at it with the ScotchBrite.

Lacquer thinner is a pretty good cleaning solvent for paint prep. I would think it would get the glue off when used with a ScotchBrite pad.

I had a good result with a very bad inside coating of dried fuel 'lacquer'. I turned the tank upside down and stuffed the hose from a wallpaper steamer inside it for a day or so. Kept rinsing it out and eventually all the brown staining just went.
Nice, low-effort solution. Suited me 

I got an aluminium boat / truck from a big hardware store which has a small amount of acid in it 
It worked a treat getting rid of the black goo from a E10 melt down

How did you get the boat inside the tank? I'm impressed.

Matthew-Brisbane wrote:I got an aluminium boat / truck from a big hardware store which has a small amount of acid in it 
It worked a treat getting rid of the black goo from a E10 melt down

E10's have meltdowns? Man, I gotta learn this language!

Yes we seem to have a small problem with out E10 10%methanol in cheap fuel. We tend to use premium fuels but ya cant pick if they happen to dilute the premium to shore up their bottom line occasionally. Truck wash CT18 it used to be called does a great job on all alloy found in boats and on trucks.

So the E10 is up to 10% ethanol. And of course in the US Fuel ethanol is denatured, usually prior to transport from the ethanol production facility, by adding 2 to 5 volume percent denaturant. I was wondering what the nature of the meltdown was. Yesterday I saw a K100 pump which had the rubber/plastic bits sort of dissolve  and wondered if that was the nature of the meltdown. Never had heard it referred to as a meltdown before though I suppose it fits. And does anyone know what the denaturant is? Haven't found any information on that. Just wondering why my little K is having such an issue with some of the local gas.

jjefferies wrote:So the E10 is up to 10% ethanol. And of course in the US Fuel ethanol is denatured, . . .

Where'd you get that idea? Food grade ethanol is shipped throughout the country. Is ethanol denatured for gasoline so folks won't drink E10? The Bay Area is decadent but I had no idea it was partying so hard. 

Yep the tank is aluminium but the level sensor and return valve is steel, so that could be where rust particles come from.

If your fuel is coloured this time of year, you may see water at the low spots of the tank. Condensation can build up in your tank, or the service station tank, or a ships tank.

I think of California weather like Victoria I guess, under 40 degrees from the equator. At a certain time of the year when the sun hits the cold shed tin roof, the warm air in the shed condenses with droplets under the tin. Same if the sun hits your bike in the morning. Or you park your bike on a cold night and the fuel is hot.

Ethanol (alcohol)  absorbs moisture, but it also attracts it, so when I do a lot of miles, I'll put ethanol in and use it up quick. Generalising, you couldn't buy ethanol blended fuel when bricks were made, so the rubber bits were not made to withstand it.

Alcohol is also a good cleaner. When they started selling E10 blend in Victoria, a lot of cars conked out a few miles after filling up with E10. If a truck, or service station, that's carried fuel for years, starts carrying E10, the tank gets a good clean, and the fuel gets dirty. Don't buy fuel from a service station that's suddenly selling E10 (or shortly after the station tanks up) wait until it gets clean.

Laitch wrote:

jjefferies wrote:So the E10 is up to 10% ethanol. And of course in the US Fuel ethanol is denatured, . . .

Where'd you get that idea? Food grade ethanol is shipped throughout the country. Is ethanol denatured for gasoline so folks won't drink E10? The Bay Area is decadent but I had no idea it was partying so hard. 

Uh, Duh, Here: https://www.eia.gov/tools/faqs/faq.php?id=27&t=10
"The U.S. Energy Information Administration (EIA) estimates that in 2019, the 142.71 billion gallons of finished motor gasoline consumed in the United States contained about 14.16 billion gallons of [url=https://www.eia.gov/tools/glossary/index.php?id=Fuel ethanol]fuel ethanol[/url], equal to about 10% of the total volume of finished motor gasoline consumption. Fuel ethanol contains a denaturant that is added to ethanol to make fuel ethanol unfit for human consumption. Federal law requires that fuel ethanol contain at least 2% denaturant by volume, but the actual amount in fuel ethanol may be higher."

It looked OFFICIAL. Must be Fake News.

Is it sill good for sniffing? Just asking for a friend.

I guess they are partying that hard!

Vinegar did the job for me. Give it a brisk shake now and then. Give it time and a couple of refills and it does a great job without caustic odors or flame dangers.

By the way if the fuel is good and you still have condensation problems, keeping the tank full helps. I've seen it here sometimes at winter with people who live at higher altitudes, and park their cars outside. A litre (one US quart?) of metho in the tank  typically used to fix it, but now you can just buy E10 instead.

daveyson wrote:By the way if the fuel is good and you still have condensation problems, keeping the tank full helps. I've seen it here sometimes at winter with people who live at higher altitudes, and park their cars outside. A litre (one US quart?) of metho in the tank  typically used to fix it, but now you can just buy E10 instead.

Likewise SeaFoam claims to do a good job with keeping condensation at bay/minimum.

If you use an acid like vinegar to clean the tank, along with the crud does it remove any sort of chemical lining that needs to be redone?

tedmckey wrote:If you use an acid like vinegar to clean the tank, along with the crud does it remove any sort of chemical lining that needs to be redone?

No.

I used Oxy laundry soaker to clean that crud oud of a tank. The rubber mount had totally dissolved and the fuel was like treacle.
Tip the whole container in a 9 litre bucket of warm water and fill the tank. Let it soak for a day. Repeat if necessary. Did a good job.

As for adding metho to the tank. I think about 100ml now and then is enough to absorb any water that's collected at the bottom of the tank.