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Tiger Dale 05-19-2019 09:36 AM

How to remove old Seafoam from tank?
Working on a friend's Harley. He left Seafoam in the full gas tank for over 2 years. It destroyed the fuel pump, etc, and left a varnish coat. What's the best way to remove?



Tritn Thrashr 05-19-2019 09:47 AM

Drop it into a canal and get a Triumph.

Tiger Dale 05-19-2019 10:23 AM


Originally Posted by Tritn Thrashr (Post 2003933576)
Drop it into a canal and get a Triumph.

Come on TT the guy is a Vienam Vetern who wants to ride in Rolling Thunder to the Wall to pay respects to his fallen Lads.

After all it could happen to a britbike.


pmorritt 05-19-2019 10:30 AM


Originally Posted by Tritn Thrashr (Post 2003933576)
Drop it into a canal and get a Triumph.

Open mouth, insert foot!

Tritn Thrashr 05-19-2019 10:41 AM

It’s the most help I can give, seeing as I have no idea what Seafoam is.

TR7RVMan 05-20-2019 01:12 AM

Hi Tiger Dale, I have no answer, but a few thoughts. I'll attempt to explain why I feel about what I found in my tribulations.

Not certain the deposits are all from Sea Foam. I sometimes use gas to wash parts. I had a 1 gallon can of California E10 91 octane fuel in a gas can for about 2.5 years. Chevron brand. I needed it to wash some parts. It had rust in it from my tank rust so couldn't be used in motor. Was in metal gas can, lid on tight. Much to my surprise the gas had really gone very bad. Smelled like solvent, was turning dark amber & was thickening. Was beginning to put a coating of some sort inside can. Can was perfectly clean prior. However none had evaporated out. I expected deterioration, but not this bad! That's why I wouldn't just blame Sea Foam. I've never personally used Sea Foam, but it's sold in my area.

I had my Tiger 750 tank stored with gas in it 24 years. Dumb!! It was only supposed to be a few months. But that turned into much longer & bike was for years behind other stored items. Getting bike out of storage the tank had about 3/16" of black gunk inside it where fuel touched metal. I'd stored with full tank of course! Still had a good 3/4 tank of old fuel. I tried many things, but no normal stuff would touch it. I didn't try acetone though. My hunch is it would have cleaned it. Carb spray could slightly dissolve it, but barely. New gas didn't seem to dissolve it at all, but wasn't E10. Just normal unleaded. I didn't try lacquer thinner as it knew it was death to paint.

The local bike shop sold Kreem tank cleaner. An acid material to dissolve gunk & rust. Then you rinsed with water & finally acetone.
The acid indeed cleaned gunk well, however also removed the protective tin/zinc layer on metal. This allowed flash rust in tank & continuing rust for ever more. E10 fuel keeps metal squeaky clean below fuel line, but promotes rust above fuel line. I had to install real fuel filters & change them often. Rust would easily pass through tap & banjo screens & collect around float needle & carb bowl. Finally top inside of tank rusted so if tank 3/4 full it would seep gas from pin hole. I ended up cleaning tank again & using Caswell sealant. So far has worked perfectly. I got 1 drop of acetone on paint & it ate paint off instantly on the first cleaning. When I did 2nd cleaning I used Kreem Tank Mask paint protector. It 100% protected original paint from further damage. Oddly the acid wash didn't effect paint at all. I wanted to keep my original paint & Tank Masked allowed me to do that.

Back to your tank. I would start by draining & filling with E10 or higher E fuel & let it soak for a week or so & see if it softens gunk.

Next I would try acetone. I would use Kreem Tank Mask paint protector first though. You paint it on with a brush. Reminds me of white glue. I did 3 coats then wrapped with Glad Wrap to keep it from rubbing off. It peels easily & dissolves with water. Even 1 drop of sweat will compromise protector. Modern Harley paint is probably much more durable than old Triumph paint, but I'd still protect it. Kreem protects against acetone for certain, I don't know about lacquer thinner or any other solvents. Test it first.

I'm pretty certain if you used any type acid cleaner it will compromise metal surface & promote rusting. They say the metal was tin or zinc plated very thin to act as a lubricant during pressing of the metal. A side effect is some resistance to rust. I will for certain say every tank I've seen acid washed rusted bad afterwards. Not just mine. I would try all means before acid washing. I basically ruined my tank. I would have been better off leaving the gunk in it.

I've learned a lot since then. My hunch is acetone alone or acetone & 2 boxes of sheet rock screws 1-1/2" in tank would have cleaned my tank & saved a lot of heartache.

So I've given no real answer, but food for thought. Kreem Tank Mask really works good, is readily available online. Nobody sold it locally. 1 bottle was just enough for Triumph tank. Harley tank would need 2 bottles.

If it comes to acid wash & tank sealant, Kreem is the very worst sealant. Don't use it. I felt Caswell worked very well. Some use POR15 to good results. Again try to clean it any other way. Many sealers take at least a week to cure well. I gave it 2 weeks just to be sure.

There are a few companies that specialize in tank cleaning, lining & saving paint. Cost is $300-500+ out here to clean & save paint. Not cheap! But much cheaper than paint job. Tank will need cleaning in any case so add that to paint job.
Good luck.

KADUTZ 05-20-2019 06:40 AM


Originally Posted by Tritn Thrashr (Post 2003933618)
It’s the most help I can give, seeing as I have no idea what Seafoam is.

Seafoam is a brand of automotive chemicals marketed in the States. They sell various additives, cleaners,and chemicals. It's primarily a retail brand. A lot of guys over here like it.

As far as your comment anyone that posts about a non Triumph should expect to receive a bit of stuff in the feedback. I can just hear what would come back on a HD Forum about a TRIUMPH question.

Not to get political here I respect Vet's. Spent some time around the VA in the mid 60's to mid 70's. Saw a lot of Fd up guys.

As far as your current problem. As you are in a VOC compliant state your aerosol brake cleaner will contain acetone. You might want to try a few shots of this to see how the gunk reacts. Another cleaner to try would be something like the Castrol Purple cleaner. Be aware it probably contains Butyl and is nasty stuff be sure to protect the areas where any liquid is entering or leaving the tank


Rancidpegwoman 05-20-2019 04:34 PM

Hi Don,
My BSA Bantam had fine rust coming through the filters and into the float bowl.
I put a magnet on the bottom of the tank, this completely stopped the rust migrating out of the tank.


Apologies for using the B word.

TR7RVMan 05-21-2019 03:49 AM

Hi Peg, I tried a magnet, but didn't seem to really make much difference. I expected the magnet to be covered with rust, but not much. Others reported magnet worked. I found it puzzling it didn't help me. I used a round neodymium magnet about 3/4" dia with hole in middle. I placed it down on right side near the bung for the front cross strap.

What type magnet do you use? Where do you place it?

KADUTZ 05-25-2019 10:22 PM


Originally Posted by Tiger Dale (Post 2003933606)

Come on TT the guy is a Vienam Vetern who wants to ride in Rolling Thunder to the Wall to pay respects to his fallen Lads.



Thinking about your friend did you get his Scooter up for the run.


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