Gregory Bender

Fuel tank cleaning and coating

Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models

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Electrolysis

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 from Charlie....

  • 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 recurrence 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 38 inch at the smaller end, 916 inch at the larger end. The big one is 1.5 inch at the smaller end and 1.75 inch at the larger end. I used a 332 inch drill bit to make the holes in it for the sacrificial anode.
Sacrificial anode.
Sacrificial anode.

Photo courtesy of Charlie Mullendore of Antietam Classic Cycle.

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

Photo courtesy of Charlie Mullendore of Antietam Classic Cycle.

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

Photo courtesy of Charlie Mullendore of Antietam Classic Cycle.

Anode after 8 hours.
Anode after 8 hours.

Photo courtesy of Charlie Mullendore of Antietam Classic Cycle.

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

Photo courtesy of Charlie Mullendore of Antietam Classic Cycle.

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

Photo courtesy of Charlie Mullendore of Antietam Classic Cycle.

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

Photo courtesy of Charlie Mullendore of Antietam Classic Cycle.

Following Charlie's lead, I now use this electrolysis technique prior to any coating. It works very well. Here are a couple notes from my personal experience.

  • If you cannot find the Arm & Hammer Super Washing Soda, just look in the pool section of your hardware store for Soda Ash (which is sodium carbonate). Soda ash is used to raise the pH level in swimming pools and is inexpensive.
  • I found coat hangers would disintegrate pretty quickly (I use a power supply). So, instead, I used bicycle hanging hooks (for hanging a bicycle from the rafters in a garage) that I purchased from the local hardware store inexpensively. It is really nothing more than a thick rod and they last a long time.
  • Keeping the tank in a horizontal position and filling it to the brim with the solution will still leave the underside of the top of the tank exposed. I found it necessary to carefully rotate the tank to ensure that all parts are submerged during electrolysis.

Evapo-Rust

Thanks to Charlie Mullendore of Antietam Classic Cycle for sending me this information via persona email. In Charlie's own words:

Just a quick note. Needed to remove some light rust from the inside of the latest customer's Eldo tank. Didn't want to go through the whole electrolysis process and couldn't find any milkstone remover locally. Did find a gallon of Evapo-Rust, so I thought I'd give it a try.

Since it was only a gallon, I had to rotate the tank to a different position every few hours. Did this for two days, then drained the Evapo-Rust, rinsed it out with water, then flushed with 92% isopropyl alcohol and dried it with the heat gun. The Evapo-Rust did an excellent job - the metal was clean and rust free. Another nice thing is it's reusable.

Horticultural molasses

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 850 T 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.

Moyer Fuel Tank Renu

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...

Phosphoric acid

Thanks to Greg Field, Greg Barratt of Stainless Cycle, and Kevin Hahn of Scrambler Cycle for providing the following information on the Yahoo! Loopframe_Guzzi news group.

Greg Field:

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

Greg Barratt of Stainless Cycle:

Milkstone remover is sold in gallons and is very reasonably priced - about USD $7.00. Use about 13 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.

I have mixed it 50:50 for the really rusty stuff. You just have to be more careful if you are trying to preserve original paint. More dilute mix just takes longer. After use it I filter it through a fine screen and re-use.

Kevin Hahn of Scrambler Cycle:

I can get a gallon of phosphoric acid for about USD $7.00 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. Every time I walk by it I'll give it a shake.

POR-15

In Gregory Bender's own words:

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.