Cleaning out an old glass tank

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I'd like to put my Fireflake Royal Blue tank back on the bike. It's full of "muck" however, and when I bought the tank last summer it quickly gummed up my carbs. Not sure what the muck is but I'd guess it's just old dried up fuel residue.

But how to clean it out? Sounds like MEK isn't a good idea as it would melt the resin. How about acetone? Would that be safe? I tried a quart of acetone and some deck screws. Dumped the stuff in and shook it around for a few minutes, until my arms got tired. That got some of it out but I think the tank needs a good long soak.

So, just looking for advice on how to proceed. Don't want to damage my tank and I'd prefer to do it myself (meaning minimal shaking - upper body strength is not my thing!)

thanks,
Debby
 

Ron L

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Debby,

Don't leave acetone in your glass tank. Chemically, acetone is very similar to MEK and both are very good solvents for the polyester resin in fiberglass. If your residue is old gasoline (varnish) then your best (and easily available) option is mineral spirits. This is not nearly as aggressive as acetone or MEK, but should be safe to allow to "soak" for a bit. If you have access to other solvents, try xylene and/or toluene. Several rinses with small amounts is more effective than filling the tank to the top and dumping it out, so I would suggest using a quart or so and slosh it then let it sit. Maybe turn it on its side after sloshing some more. Dump this out and add another quart and repeat until the mineral spirits comes out pretty clean.

P.S. - I have been an Analytical Chemist for 30 years.
 
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Debbie:

I was seeing plenty of black, gummy varnish coming from my glass tank last year. Ron can correct me if I'm wrong, but my understanding is that MTBE and ETBE do a pretty good job of dissolving the old fiberglass resins. Sealing the tank with Kreem or POR-15 is probably your best bet.

I lined my tank with POR-15 last year. Their tank sealing kit comes with sealant, a cleaner that smells like "simple green" and a surface prep solution.

The cleaner is mixed with scalding-hot water, poured in, shaken vigorously and allowed to sit, then drain and repeat. I think citri-solv or simple green would do just as well.

After drying the inside of the tank with a hair dryer on low for a few days, you use their surface-prep solution then the sealant. I let the sealant cure for a week before putting any gas in it. Two months later I drained the tank and found that the sealant still looked brand new and there was no sign of weirdness in the tank.

Can't vouch for the long term, but it looks like the tank varnish problem is solved.
 
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Dr. Good advice for a steel tank but not a fiberglass one. This may sound strange but I like gas as a solvent for spoiled gas. It's cheaper than all other things listed and very effective. A box of 100 - 5/16 nuts from the hardware and gas does wonders. norbsa
 
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One of the guys in our club suggested gas also. I guess that's worth a try. Certainly less expensive and less damaging to the resin than the other things.

So far the stuff that's come out is kind of yellowish-orangish which makes me think it's just old gas. The sealing resin coat appears to be blue (as you might expect for a blue tank).

I also still have the Hirsch kit. I could also try the cleaner from that. Don't think I want to use the Hirsch liner after hearing about people having problems with it. Caswell Plating sells a two-part epoxy liner. I might try that as it cures by chemical action not by MEK outgassing.

Debby
 
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What sort of problems have people been experiencing with the Hirsch liner? Hirsch is one of the few tank liner manufacturers that claims to have a product that works on fiberglass.

Jason
 
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Jason,

Several people have reported tank rot a year or two after applying the liner. Norbsa could probably give you more details, I believe he had a tank fail.

Debby
 
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The thing is any tiny pin hole that is unseen will make any tank liner fail. You can't see the whole inside of the tank But you must make an effort to do so or you are only wasting time and money. My Hirsh liner is still all there and still holding gas on both sides it has not melted or broken down. Gas just found it's way through some thin spot after two years and than right out of the tank. It seems to me that the only way to fix it right is to cut the bottom of the tank out and line it with Purane resen that is the stuff they make gas containers out of. Not a job for beginers. norbsa
 
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Hey all, new member here. I've finally begun restoring a 1972 Commando Interstate that I bought years ago (not running but complete), so this will likely be the first of many posts. The fiberglass tank has two very small leaks on each side at the bottom rear of the tank. I sanded the areas down a bit and put a couple of layers of fiberglass cloth down with polyesther resin, and I bought the two-part epoxy gas tank liner kit from Caswell but have not yet used it. The inside of my tank seems very clean (no previous liner material or gummy deposits); I've cleaned it out several times with hot water and detergent. Ron L mentioned that cleaning the tank out with acetone could soften the tank, and that would be bad. But, my question is, would a quick rinse out with actetone be a good thing to do before using the epoxy liner kit because it would allow for better adhesion of the epoxy to the tank (because the inside of the tank was softened up a bit) ? Also, has anybody used the Caswell epoxy liner kit? After researching all the fiberglass tank liner options it seemed the best way to go.
 
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Here's some other ideas just to stir the pot;
To avoid the flamability issues I think I would try TSP (tri sodium phosphate) in really hot water if it's still available. Used it way back when to clean everything prior to painting.
The Caswell sealer may be the best choice for glass fiber tanks; Hugh's Bultaco sells it for those spanish glass tanks whick leaked from day one. I doubt he would sell it if it didn't work.

Scooter
 
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Here's some other ideas just to stir the pot;
To avoid the flamability issues I think I would try TSP (tri sodium phosphate) in really hot water if it's still available. Used it way back when to clean everything prior to painting.
The Caswell sealer may be the best choice for glass fiber tanks; Hugh's Bultaco sells it for those spanish glass tanks whick leaked from day one. I doubt he would sell it if it didn't work.

Scooter
 
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Well I've made some progress on cleaning my tank. I've been using gasoline and a handfull of drywall screws. It's pretty clean now, and all the varnish and sludge appears to be gone. But - there's a lot of white scale deposits in the bottom part of the tank that stubbornly remain. Looks like the same stuff you get in carb float bowls from the DPO parking it for a decade or two without draining the fuel. :roll:

Any suggestions for getting the scale out? Or is it ok to just ignore it?

Debby
 
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I like to go to the hardware and buy a box of 100 5/16 nuts. there cheap and heavey with lots of sharp edges. I have seen painters set up tanks on rotiserree's(sp) made for barbaque (sp) then turn them for a day with gas and nuts slosh (sp) norbsa
 
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