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Gas tank rust, who's used what and, what's been the results?

5K views 30 replies 20 participants last post by  imlost 
#1 ·
Gang,
Just picked up an '07 that's been sitting for over 5 years. The tank has some substantial rust and, I yanked it off and dumped the fuel in a container. PHEW, that stuff stunk. And, it looked really GREEN, when I did it. Now, I've searched a bit on here in the technical section and can't seem to find any specific articles/write ups on the specifics of handling/removing rust inside these TW tanks. I've cruised Youtube and, there's a few on there. It appears I've got lots of choices as far as chemicals are concerned. I don't mind handling caustic chemicals at all. After 30+ years on an FD, dealing with some chemicals and a rusty fuel tank is well, sort of child's play. But, just WHICH chemicals do any of you use? What kind of time frame from the time you poured them in, to the time you removed them and, how well was the job done? I thank any and all of you in advance that could send some tech tips on this.

P.S. I don't think the tank is structurally damaged. I'm pretty sure it's just a nice even coat of rust but, no large flaking.
Scott
 
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#2 ·
I used a Kreem tank liner kit. It come with acid to eat the rust out of the tank, you neutralize the rust and remove the remaining acid with water. The acid turns the rust into iron and the water neutralizes it so it can safely be poured out anywhere such as a flower bed. The kit comes with some type of alcohol which removes all remaining water and moisture. Then you Kreem tank line the tank after the preparation. I have had my tank liner in two motorcycle tanks now for over 15 years. I live in Texas so I have had no issues at all. Others say they have had issues. I'm not sure if other climates are less suitable or if the preparation didn't include the complete kit. I bought the Kreem tank liner kit that was for a car gas tank. This included enough of the solutions to do two motorcycle gas tanks.
 
#6 ·
I've used the vinegar with good results. Patience is key. After the final soak rinse with water. Then if you don't do something to get the water out you'll have the bare metal flash rust. to avoid that you need to get the water out quick. I use some rubbing alcohol to absorb the water. Then dump that out and fill the tank with some fresh, non-ethanol fuel.
 
#7 ·
I have twice used POR-15 motorcycle tank repair kit with what I consider excellent results.

https://www.por15.com/POR-15-Motorcycle-Fuel-Tank-Repair-Kit-_p_106.html

The down side is it is labor intensive, very messy, and a bit on the expensive side.

My experience: Attach a long stick to the sponge brush and use that to mop up the excess liner from the bottom of the tank. If you get the liner on your hands and then touch the outside of the tank it is difficult to remove -- I think I used Chemtool on a paper towel but do it before it sets otherwise it is on there for good. As I recall, once I started there was no stopping start to finish. Plan accordingly. Remove the fuel valve and block the hole -- I think I used an old fuel valve. The quick and easy way is vinegar. You might try that way first.

Before and after:

Auto part Vehicle Automotive exterior Fuel tank Car
 
#8 ·
I have twice used POR-15 motorcycle tank repair kit with what I consider excellent results.

https://www.por15.com/POR-15-Motorcycle-Fuel-Tank-Repair-Kit-_p_106.html

The down side is it is labor intensive, very messy, and a bit on the expensive side.

My experience: Attach a long stick to the sponge brush and use that to mop up the excess liner from the bottom of the tank. If you get the liner on your hands and then touch the outside of the tank it is difficult to remove -- I think I used Chemtool on a paper towel but do it before it sets otherwise it is on there for good. As I recall, once I started there was no stopping start to finish. Plan accordingly. Remove the fuel valve and block the hole -- I think I used an old fuel valve. The quick and easy way is vinegar. You might try that way first.

Before and after:

View attachment 194726 View attachment 194728
Good details.
The Kreem tank liner process is about the same. Figure a whole day or more to do this process. One tank I had was so bad it took 3 days of sitting and reapplying the rust kill solution before it was all removed. The replacement tank on that bike was very expensive. The process is a pain on tank liners but you will be rewarded by clean carburetors for nearly as long as you have your bike as long as you use an inline filter. A side note is that with Kreem you can't use anything with Acetone once it is installed. I don't know if anything affects the POR-15 once it is set.
 
#10 ·
Hey Gang,
I want to thank all of you that have responded here. I took all of your suggestions into consideration and, also checked out a couple of youtube vids on the subject. Well, I ended up purchasing some "Evapo-rust" from Tractor Supply. It's about $22 a gallon so, I figure'd what the heck, I'll give it the old college try. Well, the tank, as stated had what I thought was minor rust. But, upon getting an inspection camera in there and a long flash light, I was in for some strategic work. I put the whole gallon of that evapo-rust in there and, followed the instructions. I let it sit for four hours. The instructions say 2-4, depending on severity of the rust. Since I was in my little man cave doing other things on the T-dub, I'd shake that tank every now and then to make sure the solution was getting to all parts.
After about 4 hours, I emptied it. The majority of the innards were pretty clear now. But, down in the crevis's, near the welds, was some pretty tough left over rust. So, I picked away it with some stainless steel, 1/8" welding rod (tough stuff, doesn't bend that easy) and decided that, I'd run the treatment again. Oh, when I thought I was done with the first treatment. I'd emptied about 85% of the solution and, inserted a couple of hand fulls of small, about 1/2" to 3/4" sharp edged ROCKS. I then would vigorously shake that tank in every possible direction 'till I was out of breath. I'd let it sit 'till I recouped and, hit it again. I did that, on and off for about 20 minutes. I then dumped out all the rocks and remaining solution. I got a lot more out of it by doing that. The tank was looking really good but, with the use of that inspection camera, I found out I still needed a bit more soaking. So, back in the solution went. It's gonna remain there over night. We'll see what's what in the morning. In the mean time, time to install my new, wazoo LED turn signals, yahoo!
Scott
 
#25 ·
Hey Gang,
I want to thank all of you that have responded here. I took all of your suggestions into consideration and, also checked out a couple of youtube vids on the subject. Well, I ended up purchasing some "Evapo-rust" from Tractor Supply. It's about $22 a gallon so, I figure'd what the heck, I'll give it the old college try. Well, the tank, as stated had what I thought was minor rust. But, upon getting an inspection camera in there and a long flash light, I was in for some strategic work. I put the whole gallon of that evapo-rust in there and, followed the instructions. I let it sit for four hours. The instructions say 2-4, depending on severity of the rust. Since I was in my little man cave doing other things on the T-dub, I'd shake that tank every now and then to make sure the solution was getting to all parts.
After about 4 hours, I emptied it. The majority of the innards were pretty clear now. But, down in the crevis's, near the welds, was some pretty tough left over rust. So, I picked away it with some stainless steel, 1/8" welding rod (tough stuff, doesn't bend that easy) and decided that, I'd run the treatment again. Oh, when I thought I was done with the first treatment. I'd emptied about 85% of the solution and, inserted a couple of hand fulls of small, about 1/2" to 3/4" sharp edged ROCKS. I then would vigorously shake that tank in every possible direction 'till I was out of breath. I'd let it sit 'till I recouped and, hit it again. I did that, on and off for about 20 minutes. I then dumped out all the rocks and remaining solution. I got a lot more out of it by doing that. The tank was looking really good but, with the use of that inspection camera, I found out I still needed a bit more soaking. So, back in the solution went. It's gonna remain there over night. We'll see what's what in the morning. In the mean time, time to install my new, wazoo LED turn signals, yahoo!
Scott
Hi Scott, thanks for your detailed rust treatment explanation. I have one question: Because the TW tanks have that circular 2" deep neck sticking down inside the filler hole, HOW DID YOU GET THE ROCKS OUT? I would think they would collect around that neck and you'd have a terrible time shaking them out. What's the secret?
 
#11 ·
I've found the chellation fluids (Evapo Rust, Metal Rescue, there's others) tend to be a little optimistic on how long they take. Most advertise anywhere from 4-12 hours for "heavy" rust, I've found that is often more realistically 3-5 days. Just turn the tank around every few hours to get all of the internal surfaces. You can dilute it with water to increase the volume up to about 50/50, it does still work but just a lot slower. Keeping it warm is also key. The labels warn it needs to be at least 65* or so, but I found warmer=faster. Stick the tank out in the sun on a hot day and the action is considerably accelerated.

I've used vinegar in the past and it does work well. It's also like $2 a gallon instead of $25. Fill 'er up and let it sit for a day or two. Dump it out and immediately refill with water and a few spoonfuls of baking soda. Dump that, repeat once more to make sure all the acid is neutralized (or it will flash rush in no time), and you're done.

The liner kits are hit and miss. Prep work is extremely critical to getting a half decent result. Generally to me they seem to cause more problems than they solve. I dealt with these constantly at the dealership where these DIY liners would just slowly dissolve and flake off, causing all sorts of problems with carburetors, fuel pumps, ect. They'd clean the carburetor out and a week later it's clogged with goo again. If you clean the tank properly using one of the above methods there is no need to then also do a liner. If the tank is so badly rusted it's leaking, don't even bother. Toss it. Stock TW tanks are cheap and plentiful, just replace it with one in better shape, or get one of the larger capacity plastic ones.
 
#12 ·
Thank you Sir for your experience here. Yep, I too think some manufacturers get a bit over zealous about just how well their products work and in what kind of time frame. Well, as stated, the 2-4 hours initially did do the job but, not as good as re-doing it and leaving it in overnight. I shook the tank quite a bit before I went to bed and, got up early and shook it again. At about 10:00 this morning, I emptied all the chemical out and washed the tank out several times with HOT water. It's now as good as it's gonna get. 98% of the rust is out. I have tiny spots, here and there I can see with my bore scope. Big deal. I have a new pet cock on order that's to be here on Wed. It of course, has new screens on it and, I'm planning on setting up an inline filter too. All I gotta do now is yank the carb and go through it to see what kind of goo is inside it.

I'm anxious as heck to get this Blue Noid running. We've had it now for almost a week and all I been doing is putzing with it in things like cleaning the tank, messing with new, LED sequential turn signals that don't work, and a few other odds and ends. Still need a chain guard and chain guide (bottom piece). Ordered up a new set of brake and clutch levers. The brake lever was broke. So, I'm getting there, just slowly. Thanks again for your assistance here.
Scott
 
#13 ·
A handful or two of small (1/4" or less) nuts a quart of vinegar, seal and shake the tank like it's a maraca should get out all the remaining rust, baking soda rinse then soap and water.
The only 'liner' I've found that works is made by a fellow named Bill Hirsch (hirschauto.com). Seems expensive at $30 a quart, BUT the pint ($20?) will coat two or three tanks. Pour into clean dry tank, swirl all about to coat every surface and pour the remainder back into the can to use on the next tank. I have two bikes with it in the tanks, one since about 1995... they still look like 'new' inside . Don't know what it is, seems like white plastic, nothing but Toluene(?) will apparently screw with it, none of the common gas additives, alcohol or fuel injection cleaners have any effect on it. I've put it into 'irreplaceable' tanks that were so far gone, the only thing keeping the fuel in was the paint holding the rust in place. They never rust again. If my TW starts showing any rust (thanks for 15% alcohol B.O.) that's what I'll coat it with. The 'kreme' and like kits (with directions followed diligently) all ended up flaking/peeling/failing.
 
#14 ·
Don't tell my wife this. After a few days with almost 2 gallons of metal rescue in the tank and in the bathtub it was mostly clean but still had the rust in the welded seams. I had a jar full of the old style small square 7/16" nuts with sharp edges. Don't use SS because you might need a magnet tool to get them all out. In the tank they went with about a half gallon of the fluid. I then wrapped the tank in a heavy moving blanket and tied it up with parachute cord so it would not come off. Next the wrapped tank went into my wife's clothes dryer on the No Heat cycle and it rocked and rolled for a 45 minute cycle. What a racket it made all the while but the wife was at work. After untying and emptying the fluid and getting all the nuts out almost all of the rust in the crevices was gone. You can never get it all out. Dry the tank real fast so it does not flash rust. If you plan to coat the inside just follow the instructions on whatever product you use. The key to success when coating the inside is to get the entire inside completely coated so there is absolutely no surface left uncoated with exposed metal. Any uncoated spots inside the tank will allow the fuel to get under the coating and start to flake off. Once you coat the inside you can't get it back out so you have just one shot at doing right.

GaryL
 
#15 ·
FWIW , my 87 came with a really nasty looking tank .

A trusted friend suggested " The Works " toilet bowl cleaner . Being that the inside looked looked like a toilet bowl , I figured what the heck .

Came in a 2 pack which was $10 or so .

Poured in the 1st bottle and water to top it off ( with the recommended shake rattle and roll nuts and bolts ) Next day emptied and very surprised . Repeat with the other bottle and called it good .

Made sure to install inline filter , but no problems so far .
 
#16 ·
This is a crackup. Reading about all the remedies for rusted tanks. I thought mine was pretty bad when we purchased it (along with the bike) about a week ago. But, with a double try of the EvapoRust, it's a darn clean and almost rust free tank. As has been stated, you can never get ALL of the rust out. But, with the use of a fuel filter, we all should be good to go. Can't wait to get the Blue Noid running for the first time. My new petcock should arrive today and, I went through the carb last night after a five year hiatus of not running and, it was actually in pretty good shape. Some varnish here and there but, I took care of all that. So, we'll see how goes when I try and start it later today.
Scott
 
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#17 ·
I bought a Honda Passport C70 that I thought the gas tank was rusted beyond repair. I used Apple Cider Vinegar. Plug the tank and make sure the cap seals tight. Pour about a quart of Vinegar in the tank. Shake it up for about 2min. Now just leave it alone and shake it up every time you think of it. When commercials are on TV, between programs or when you raid the refrigerator. The next day shake it up and dump the vinegar and rinse with garden hose with nozzle. Then repeat one more day. Keep doing it until you get the results that please you. Dry the inside of the tank the best you can. Put about a pint of gasoline and about 4oz of MMO (Marvel Mystery Oil) in the tank and shake it up. Now the raw metal will have a light coating of oil on it!
 
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#18 ·
I'm surprised this hasn't been mentioned yet but on a tractor that had a really rusty tank we emptied and filled with water and washing soda and hung a sacrificial annode in the tank and hooked a battery charger to the annode and the tank and left it on for a few days, I would pull the annode every day or so and grind the nasty stuff off the annode with an angle grinder, it worked really well and the tank cleaned up real shiny.
 
#20 ·
What, may I ask is, "Washing soda"?
Scott
 
#21 ·
Washing soda is an old time detergent booster. The electrolysis method works great for sure.

GaryL

All-purpose flour
 
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#22 ·
Washing soda is an old time detergent booster. The electrolysis method works great for sure.

GaryL

View attachment 194900
Thank you, I know a bit about baking soda but, I guess I've never heard of it being called "Washing Soda".
Scott
 
#24 ·
Ya know,
Talk about Freudian slips, I just glimpsed at that box and thought, hmmm, baking soda used as washing soda. Not a good plan to reverse those as you say. Thanks for pointing that out.
Scott
 
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#26 ·
I have had good luck with Evaporust. The nice thing about it is, it doesn’t harm paint. As long as there are no pinholes, my preference is not to coat. I’ve heard of a lot of failures. If a tank coating does fail, then you’ve got a real mess on your hands. Keep the tank full, or if you are mothballing a bike drain out all the fuel and coat the inside with fogging oil.

Of course the trick is to know when you are going to park a bike long-term. I did the tank on myXL 100 and it’s been sitting for about 8 years now up at my family’s property. It’s a mess again. :-(
 
#29 · (Edited)
I've been using evaporust for over 16 years. Always bought it in 5 gallon size. Lasts a very long time and works great. Have found that the entire piece submerged in the solution works best. Heavy rust is usually dug out first and then soaked. No problem leaving it in for a long time. Only eats the rust. Will not hurt the steel.

Back to fuel tanks. I use muriatic acid and put a gallon in the tank and close it with plastic tape. Do Not get your gas cap near this or any other acid.
Keep rotating the acid in the tank for about 15 minutes. Up to 30 mins max at a time. Pour the acid back into its container. Rinse immediately the tank with dish soap and watee. Repeat three times. Lots of rinsing in between. Then pour in a bunch of baking soda with just enough water to slosh it around. It is very important to neutralize the acid. Same for vinegar. Rinse well with clear water. Dry quickly using air nozzle.
Final thing to do is to mix solution of gas and motor oil ( 90% gas to 10% oil ) . Shake it around and empty it out.
A bit of work? Yes, but it works well.
Forgot to add, wear a proper respirator with catridge rated for the acid. And do this outside.
 
#30 ·
And be careful with that Muriatic Acid. Forty years ago I drove a Cement Mixer for a family friend who had a concrete/pool company.

I was through for the day pretty early, so I started at one end of the place and tried to tidy up a bit.

I came across a gallon jug with no label on it so I took a good long breathfull of it deep down inside me. I learned my lesson and lived to pass it on, but it was a painful minute or three.

Sent from my Pixel 3a XL using Tapatalk
 
#31 ·
And be careful with that Muriatic Acid. Forty years ago I drove a Cement Mixer for a family friend who had a concrete/pool company.

I was through for the day pretty early, so I started at one end of the place and tried to tidy up a bit.

I came across a gallon jug with no label on it so I took a good long breathfull of it deep down inside me. I learned my lesson and lived to pass it on, but it was a painful minute or three.

Sent from my Pixel 3a XL using Tapatalk
We were wondering what happened to you. 😜
 
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