View Full Version : How to repair/seal a rusted gas tank


g21-30
December 8th, 2008, 04:39 PM
I found the following article on the 'Net. It does not appear to be copyrighted. "I" did not create this document, so the "I" in the document is not me.

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Motorcycle Gas Tank Rust Removal Technique

Before you consider doing the following, please check the METHYL ETHYL KETONE (MEK) safety sheet at:

http://www.jtbaker.com/msds/englishhtml/m4628.htm

1. Get a Kreem Fuel Tank Liner. Available at Dennis Kirk, part #3160, $14. You can also order the complete tank prep kit for $26 if desired, but in compliance with CBMMA, I took an even cheaper approach. The kit basically has three parts: part A (acid), part B (MEK), and part C (the liner).
2. Empty the fuel from the tank if it is not already. Remove the petcocks and fuel filters from the tank.
3. Block the openings for the petcocks. I fashioned two stops using a couple layers of heavy corrugated cardboard wrapped in duct tape, cut to fit and held in place with the petcock screws. I sealed them on with cheap silicone sealant (which comes off fairly easily afterward). A wood or metal stop might be more appropriate, but this worked fine for me.
4. If the tank sat with gas in it that evaporated (like mine), clean the tank with a little acetone (or MEK) to remove the worst of the varnish left by the gas.
5. If the tank has large chunks of rust, you may want to add BBs (or chain, etc.) and rotate the tank for a bit to remove the worst of it. Mine didn't need this since it had only small flakes of loose, powdery rust.
6. Mix up a 10% solution of muriatic acid. This is available from most hardware stores as a 20% solution, so just dilute it with an equal amount of water (always add acid to water, not the other way around). I mixed half a gallon of acid with half a gallon of water for my tank. Pour the solution into the tank, taking care not to get any on the paint, unless you plan on repainting. This goes for the acetone or MEK as well.
7. Set the tank on one side for about ten minutes. Then switch to another side for ten minutes... etc. so all the sides get cleaned. I let the whole tank sit with the acid solution for a total of about an hour and a half I think. Look through the gas cap carefully with a flashlight to check the progress periodically. The tank should look brand new inside when done.
8. When all the rust is gone, dump the solution and rinse the tank very thoroughly with water. Immediately clean all inside surfaces with a little acetone or MEK and empty out as much as you can when clean. Any small amount leftover will only slightly thin the liner (which contains MEK anyway). Do not let all the MEK evaporate completely because oxidation will begin right away. Immediately proceed with the next step.
9. Pour in liner according to its directions and follow remainder of directions from liner.
10. The liner may end up a bit lumpy looking, but this is okay, the tank at least sealed and protected. I would recommend doing the whole process outside (for fumes) with a hose handy for diluting any spilled acid. The acid bath may open leaks in the tank if the rust was very severe, so be prepared. If not too large, these can be patched with epoxy filler or by soldering. I was fortunate enough not to have any leaks. I should also mention you may want to check the gasket on your gas cap before you begin any of the process. Mine was so hardened it did not seal properly, but I found a thin rubber gasket at a plumbing supply store for $1.50 which I fit on top of the old gasket for a perfect seal.

======Another technique follows:===============================

RED-KOTEŽ FUEL TANK LINER
STAYS FLEXIBLE - Will never crack or peel off.
ALCOHOL RESISTANT - No expensive come-backs.
BRIGHT COLOR - Both you and the customer can see results.
COVERS RUST - Seals old rust in and prevents future rusting.
SEALS LEAKS - Gets the multitude of pin-holes you can't find.

Damon Industries, Inc. P.O. Box 2120 Alliance, Ohio 44601 E-mail: Rad@DamonQ.com
Phone: 330-821-5310 Fax: 330-821-6355 Toll Free in North America: 800-362-9850


Red-KoteŽ is a new polymer coating developed by Damon Chemical. Red-KoteŽ is resistant to gasoline, diesel fuel, alcohol and other fuel additives. Its major use is to seal leaking fuel tanks. Solvents such as methyl ethyl ketone, acetone, methylene chloride and propylene oxide will completely dissolve the polymer. Other industrial solvents will affect the coating but, not completely dissolve it.

Red-KoteŽ is easy to use if the directions are followed closely. It seals the multitude of small leaks that often form where the straps wrap around the tank. You fix the obvious leaks and Red-KoteŽ seals the rest. Contrary to what some people will tell you, rust does form inside gas tanks. The cause is condensation and water in gas. Red-KoteŽ seals rust under the coating so it cannot flake off to plug fuel-line filters or cause engine damage.
Further rusting is reduced also. Red-KoteŽ is a safe and sure way to solve your customer's problems and increase your own profits. Since most of the time is spent in drying you can be doing other work while Red-KoteŽ makes you money.

Red-KoteŽ also offers the advantage of not interfering with the reinstallation of the tank. External coating, especially fiberglass, are sometimes too thick to allow reinstallation with the original straps and bolts. Some of the specific advantages of Red- KoteŽ are as follows:

1. The coating is very flexible and does not crack as do some of the others. This gives the repair a much longer life. Tanks coated in 1984 are still doing well.

2. The polymer was specifically chosen because of its tight adhering qualities. In comparison to some other coatings, Red-KoteŽ does not peel off even when the metal is bent. This protects against loosening of the coating by vibration or denting of the tank.

3. Red-KoteŽ is resistant to methanol. In fuels with a high percentage of methanol the coating is bleached, but remains tightly bonded to the metal. In 1985 the federal government allowed 5% methanol in fuel. Standard Oil's ice-guard is 0.5% methanol. The cheap gas tank anti-freezes are methanol. (The good ones are isopropanol.) Some gas tank liners are dissolved by methanol into sticky lumps and strings that plug the fuel line. This will not happen with Red-KoteŽ.

4. Red-KoteŽ dries faster than many other sealers saving you time. You can reduce time further by thinning with Methyl Ethyl Ketone and using two thin coats instead of one thick coat.

5. Red-KoteŽ levels very well. You will not get a wide variation in thickness as with some other coatings.

6. Red-KoteŽ is thicker and usually requires only one coat as opposed to two coats for many other coatings. Holes up to 1/32nd may be coated and sealed safely. Rust is sealed in so that it cannot flake off.

7. The bright red color is easily visible to you and the customer. You can be sure you didn't miss a spot and the customer can see you did something. Some coatings are almost invisible. The new dye does not leach into gasoline (turning it pink) when the vehicle is not used for long periods of time.

Packaging: Red-KoteŽ is available in one quart metal cans packed 9 per case or in one gallon metal cans packed 1 per case. It is backed by our guarantee and our over 53 years of service to the radiator industry.

Directions:

1. Empty all fuel from tank.

2. Remove sending unit, float, feed lines, filters, anything that could be clogged by the coating.

3. Remove any loose rust by tapping on the tank with a rubber mallet or by tumbling with a piece of chain in the tank. Flush out debris.

4. Clean tank by steaming for about 15 minutes. Boil out is not recommended because the high alkalinity removes the tin from the terne plate. A standard water soluble degreasing chemical works well.

5. Any leaks larger than 1/32nd of an inch should be repaired by soldering or your usual method.

6. Make sure that the tank is completely dry before continuing. This is very important. Without a blower, drying may take up to 12 hours. The use of a blower to circulate air through the tank will cut the time to an hour or so. The fastest method is to drain the tank for 5 minutes and then pour 1 pint of Methyl Ethyl Ketone into the tank, slosh thoroughly and pour out. Repeat with a second pint of M.E.K. and you are ready to use Red-KoteŽ immediately. Do not re-use the first pint of M.E.K., instead let it evaporate safely away from flames or sparks. The second pint of M.E.K. may be used as the first pint on the next job. One quart of M.E.K. will only absorb up to 3 ounces of water. This is why it should not be reused.

7. Cover all open holes in the tank by plugging or covering with tape, except the one to be used for pouring in the coating.

8. Pour one to two quarts of Red-KoteŽ into the tank and cover the last opening. You can get by with one quart on tanks of about 12 gallons or less. We recommend two quarts for larger tanks to make sure you get the coating to flow behind all the baffles.

9. Tip the tank onto each side and slosh the coating around to completely cover the inside. Use a rocking motion rather than shaking. It is important to do a thorough job or you may miss parts of the tank behind baffles.

10. Drain out the excess coating and cover tightly to save for reuse. The best method is to stand the tank up with a corner drain hole over a can to collect the excess as it drips out. It is very important that you do not leave puddles in the tank.

11. Open all tank openings to allow the best air flow. Air dry for 8 to 24 hours. When cured there will be almost no solvent smell left in the tank. If the coating is not completely cured before fuel is added the curing process will be stopped. Do not use open flame or an electric element for drying or an explosion may result. Do not blow air into the tank until at least 60 minutes of drying time have passed. Using air sooner may cause bubbles may form in the coating.

12. If the leaks or rust are severe it is a good idea to use a second coat after the first coat dries completely.

13. Reassemble and install the tank on the vehicle.

14. For clean-up use methyl ethyl ketone, acetone or a quality lacquer thinner with no alcohol in it.

Tips & Hints:
Do not leave the can open to the air as it will thicken or form a skin on top. When Red-KoteŽ is reused after pouring it back out of a gas tank it may need thinning before reuse. Red-KoteŽ may be thinned with M.E.K. or Acetone. Do not use lacquer thinner to dilute Red-Kote. For removing water from the tank prior to coating you may use acetone. Acetone absorbs much more water than M.E.K. and is less expensive. We do not sell acetone. Most shops are punching a hole in a corner of the tank to aid in draining it completely. Then they solder in a drain cock. Do not solder or weld on the tank after it has been coated. The coating will turn to ash if heated above 250°F.

Some of our customers have reported a way to speed up the process significantly. They are thinning Red-KoteŽ about 20 - 25% with M.E.K. (1 part M.E.K. to 4 or 5 parts Red-KoteŽ). This allows the Red-KoteŽ to dry in only a couple of hours in many cases. They also report that using air to dry the inside does not cause the bubbles that form when straight Red-KoteŽ is dried with air. You will get a much thinner coating.

We are told that two of these thin coats still take less time to dry than one thick coat. Red-KoteŽ does not stick well to plastic tanks or to plastic parts inside a gas tank. Do not coat over other coatings. Remove old coatings completely first, using M.E.K. or other solvent. Call us if you have a problem. The two most common problems we see are:

1) Not completely drying the tank of water before coating. Red-KoteŽ will not stick to wet metal. When it dries it will peel off in sheets.

2) Not allowing the Red-KoteŽ to dry completely. If Red-KoteŽ is not completely dry or has puddles left it will form strings or flecks in the gas. These may get past the fuel filter and plug carburetors or injectors. Puddles of Red-KoteŽ left behind baffles or in corners may never dry completely. This is because a skin forms over the puddles and prevents drying underneath. Once the skin ruptures Red-KoteŽ forms strings in the gas. Damon Industries guarantees the product only, not your application of it. After application to over 50,000 cars we have seen 7 problems. All were application errors as described above. We have never seen failure due to ageing. Both of these conditions are prevented easily by proper drying. All problems are correctable by stripping out the Red-KoteŽ with M.E.K. and recoating. We recommend that you tell your customers not to use fuel additives containing methanol or methyl alcohol. We have had instances of methanol pulling the red dye out of Red-KoteŽ which turns the gas red. This has not caused any damage to our knowledge. Usually only "cheap" additives contain methanol. Good products contain isopropanol or other solvents. Most engine warranties are voided by the use of methanol anyway.
Do not rush the job. In many cases it will take more than one day to do a job worthy of your time and guarantee.

Red-Kote.pub - 3/14/04

kkim
December 10th, 2008, 03:47 AM
I looked into coating products when I ended up with a severely rusted BMW (car) gas tank. What I found was that the results was only as good as the prep job. When not done right (and it is fairly hard to do right in an enclosed gas tank) the coating will start to delaminate from the tank walls and eventually prove to be more of a problem from coating debris in the fuel system. When done right, it was an excellent choice.

Instead of chancing it (and getting stranded somewhere), I ended up purchasing a new replacement gas tank and installing it.

TonyKZ1
December 10th, 2008, 08:07 AM
I had this rusting problem on my old bike, a '75 Kawasaki KZ400. After having fuel filters clog up on me multiple times due to so much rust in my tank, not good while you riding down the road and loose power.
I had a local radiator & ac shop clean my tank and coat it. He's had quite a bit experience with the gas tanks as it turned out and didn't damage the outside paint job. He used the red-coat product I believe as the tank afterwards had a red opaque coating on the inside.
My Ninja 250's tank was already coated from one of the p.o.'s with a whitish creamy coating and that's working fine too.
Tony

kkim
January 5th, 2009, 02:57 AM
An example of what can happen when coating starts to delaminate.

http://www.kawiforums.com/showthread.php?t=125152

KnoxNinja
January 5th, 2009, 03:06 PM
An example of what can happen when coating starts to delaminate.

http://www.kawiforums.com/showthread.php?t=125152

Haha... I'm glad my turmoil is helping others. The coating inside my tanks is a white/gray kind. I'm going to be redoing both tanks soon, probably with Redcoat. It tends to loosen most at the top of the tank and around the cap, as that area is exposed to air the most. While it's way better than having your tank rust through, it can still be problematic if you don't watch it.

TnNinjaGirl
January 7th, 2009, 04:45 AM
For what it's worth we have used Kreem several times on old British Cars. It seems to work really well. The application process is a little tricky, but given these were huge tanks with baffles and such inside. I'm sure on a motorcycle tank it'd be easy-peasy.

KnoxNinja
January 8th, 2009, 12:51 AM
Whatever I can get that works is fine with me. Gotta keep the Ninjas happy!