greg bender

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Fuel tank repair

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The fuel tank on my Ambassador was showing signs of rust on the inside. So, prior to having it painted, I used a several stage system designed to (1) remove gum, sludge, and varnish, (2) remove rust and prepare the tank for the sealer, (3) seal the tank against any further damage. The kit worked great and I've had no problems. The kit even came with a patch for repairing holes or weak areas, but I did not use it and cannot attest to it's ability. I purchased the entire kit from a company called POR-15. They call it a "cycle fuel tank repair kit".

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Thanks to Ken Giese for providing the following information on the Yahoo! Loopframe_Guzzi news group.

I picked up a gallon of horticultural molasses at a feed store. The 850T has a "collar" inside the fill hole which REALLY limits access and sight angles. Top to bottom filling really appealed to me considering the top of the tank was probably where the bulk of the rust was. I forgot to mention that I rinsed the tank out first with soap and water to loosen things up. I also shook some bb's around. A real hassle getting them out as the filler hole collar leaves drainage to the petcock holes. Plugged up those holes and filled 'er up.

Nothing happened for a few days (molasses is a long process) but about the 3rd day I noticed the solution was draining out the top onto the floor. Topped it back up and even more on the floor the next day. Then it started "burping" every once in awhile. Obviously some sort of chemical reaction. I decided to put the cap back on and shake it up in case of settling. Wow. When I opened the cap it exploded out like a shook up cola bottle. What a mess, so a word to the wise. All said I let it set for about 10 days, drained it and rinsed with water. Bare metal. I was impressed!

After it dried, I sloshed around some phosphoric acid to prevent rusting until I add gasoline. Figure I can treat the tank again in a few years if desired rather than add a sealer.

Update:

My yearlong, slow restoration project is nearly complete; meaning that blasted tank sat with nothing in it and rusted again! Not bad, but more than flash rust. The phosphoric acid treatment only lasts so long by itself. So, this time I sealed it with POR-15 after researching the product and corresponding with their service dept. I again got the rust out with molasses. I didn't buy their kit, just the sealer. Terrific product. Yes, if the bike was ready to ride I could have just filled it with gas and been done with it as originally intended. Interestingly, POR-15 thought I'd be ok "naked" with a full tank of gas. But with the next step of painting and a planned Oct launch I like knowing it's sealed.

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Thanks to Greg Barratt for providing the following information on the Yahoo! Loopframe_Guzzi news group.:

Milkstone remover is sold in gallons and is very reasonably priced - about USD $7.00. Use about 1/3 gallon, and then fill the tank with water to the very top. Let it sit for a day or so (in the sun helps a little), empty it, rinse it, and dry it with a heat gun and a little alcohol. The phosphate leaves a coating to inhibit rust. The solution also can be re-used. Just filter the crud out, and bottle it up.

You can get milkstone remover at Tractor Supply Company. Dairy farmers use it to clean their milking equipment.

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Thanks to Kevin Hahn for providing the following information on the Yahoo! Loopframe_Guzzi news group.

I can get a gallon of phosphoric acid for about $7 at the local farm store. Its labeled as pipeline cleaner or milkstone remover.

Works good as a rust remover but don't get it anywhere near aluminum. That includes the petcock. It will eat that away in a couple of days. For badly rusted tanks I will fill it with a mix of the acid and water and let it sit. Sometimes I will put some nuts and bolts or a length of chain it it to knock some of the stuff loose. Everytime I walk by it I'll give it a shake.

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Thanks to Greg Field for providing the following information on the Yahoo! Loopframe_Guzzi news group.

Milkstone remover for dairy bulk tanks. Available at Fleet Farm-type stores. Or OSPHO, available at good hardwares.

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Thanks to ??? McMillen for providing the following information on the Yahoo! Loopframe_Guzzi news group.

I have a bottle of some stuff called "The Works" - says it removes rust from bathrooms - has phosphoric acid and other stuff it says... after treating the interior of a tank with it one would want to "stop" the acid with baking soda solution washdown...then maybe a half ounce of marvel mystery oil in the tank before every fill up.

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Thanks to Charlie Mullendore of Antietam Classic Cycle for providing the following information on the Yahoo! Loopframe_Guzzi news group.

Charlie followed the instructions presented at Ken French's Electrolysis Setup. Here are a few notes and several photos...

• You want Arm & Hammer "Super Washing Soda" which is normally found at the supermarket in the aisle with the laundry detergent. Comes in a yellow box. Here's where I found the procedure in the first place: http://650rider.com/Content/pid=6.html I bought two large (5 gallon?) plastic buckets to mix the solution in and to drain it back into when done. Used a large plastic cup to transfer the solution from the bucket to the tank.
• I've had no reoccurance of rust so far, but it is winter (low humidity) and I do keep the tank full as much as possible.
• The rubber plugs were purchased at the local Ace Hardware, any good hardware store should have them. I've seen them in the hardware section of the local Lowe's. You want the black rubber not cork ones. The small ones are 3/8" at the smaller end, 9/16" at the larger end. The big one is 1.5" at the smaller end and 1.75" at the larger end. I used a 3/32" drill bit to make the holes in it for the sacrificial anode.

Sacrificial anode.

Placed into the tank. Tank filled with a solution of Arm & Hammer Washing Soda water.

Electricity supplied by battery charger. 12 volts, 6 amps.

Anode after 8 hours.

Final cleaning of the tank. Drained the solution, then flushed thoroughly with the pressure washer.

Clean metal. Two large bottles of rubbing alcohol are next, sloshed around to disperse any remaining water.

Drying the tank. Drained the alcohol, then used the heat gun on low to dry the insides.

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Thanks to Lannis Selz for providing the following information on the Yahoo! Loopframe_Guzzi news group. In Lannis' own words:

After years of fighting fuel tanks, trying to clean old braze out of seams to get a clean weld, experimenting with sealers, trying to figure out how to get the old sealer out (because it never seems to hold), I found Moyers Fuel Tank Renu and will never go back.

Having a known-good fuel tank is important to me, I hate leaks, I hate fires, I hate little stringers of goo in my jets stopping me in the rain on a long trip. And since it's something you only have to do ONCE per fuel tank if it's done right, it's worth it.

Moyers takes your tank, plasma-cuts the bottom out of it, bakes it at 800° F to burn all the old goop and solder out, fixes all the seams and leaks with MIG or TIG welds as needed, straightens it out, welds it back up, grinds and handworks the seam so you can't see it, seals it with some sort of red sealer that never quits, gives the outside a coat of primer, and sends it back. My last tank was USD $290.00 for this treatment; I've never had one leak or fail after all this...

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