Fiberglass Fuel Tank Advice Needed.

Gentlemen,
I'm about to refinish my fiberglass tank and side panels on my 71 750 roadster. My tank has two small blisters on the edge of the fuel filler about 1" to its right. They appear to be from fuel osmosis as I have squished fuel from inside one. Examining the tank insides with a bright light and mirror shows the bottom panel of the tank to be a light blue in colour. The top/ side skin is a green akin to olive drab in colour. The change appears to be where the two meet along the bottom of the tank. The inside of the filler neck had a tan coloured sealant merging the lower metal in the neck to the fiberglass. This was coming unstuck so I have now removed it. The plan at the moment is to flush out the tank with some acetone or MEK then seal it with Red Kote. Were these tanks originally two colours of fiberglass or am I looking at a repair from the past? Has anyone else used Red Kote and if so any recommendations for a successful outcome? What was that tan sealant I removed?

Thanks,
Simon.

Hey Simon, used to use a lot of red coat on automotive tanks. great stuff. Was going to use it on my own fiberglass tank. The cans I have are several years old now, but when I read through the directions, said not for use on fiberglass. possible they have a new formula now, i dont know.

Dan

I haven't used any of these sealers yet but Caswell seems to be very popular around here. If you do a search for "gas tank sealer" you should get lots of info and testimonials.

I just purchased the Caswell product and am just waiting for the weather to warm up a bit to use it. I will let you know how it is to use, As far as how long it lasts that may take awhile, But some have said it is the best, I shall see, Chuck.

I sealed my glass tank with Caswell three years ago and it's still doing fine. I've heard Redkote is ok too, but have no personal experience with it.

My tank didn't have any blisters or soft spots when I sealed it, but I did run gas in it before I sealed it and the carb slides became stuck with brown goo. It only took two weeks for that to happen. Seems ok now though.

Debby

2 years of Red-kote and it has been fine in my fiberglass tank with 10% ethanol fuel. The original Damon Industries instructions from their website do not say not to use on fiberglass but their distributor has added a statement in. I think as long as you rough it up well beforehand it will stick. (Drywall screws, etc)

Whatever you use it will not last forever (even Caswell epoxy) so plan accordingly. I bought a used 850 steel tank and will have it repainted to match - not nearly as nice - seams ya know.

Lots of additional info and horror stories on fiberglass tanks melting in the boating world.

Russ

Steel replacement tanks are getting cheaper - only available for Roadster or Interstate, though.

bought a used 850 steel tank and will have it repainted to match - not nearly as nice - seams ya know.

Click to expand...

If you can find a Mk3 roadster tank, the seams are lapped rather than pinched and other than the lack of "buttons" for the rubber band is nearly impossible to tell from the glass tank!

Thanks for the feedback everyone. I'll clean out the inside with some methyl hydrate and a couple handfuls of nuts for abrasion purposes. Once its had a couple days to dry I'll give it a first coat of Red Coat sometime this weekend. A couple of the local Norton knowledgeables recommended today to do three coats, each about a week apart then let the tank sit and 'cure' for three or four weeks before refinishing.I'll keep you updated as it progresses.
Cheers,
Simon.

I still have a glass tank on my Commando. No problems, so far. From what I'm reading here, I will probably develop a leaker someday. That being the case, I'm looking for a metal tank. The coating solution seems temporary, as well as fraught with problems. I think it's best to bite the bullet, metal, that is and be done with it. What say all of you?

You may well be right Jim. New metal tanks are now being reproduced in roadster and interstate form. I believe they are made in Pakistan. I understand some of the seams are located differently and the base may not fit quite the same as an original though I haven't tried to fit one myself.
If sealing this doesn't work out I may spring for a Terry Baker tank. In polished aluminium they just look amazing and there's no internal rust issues either.
Cheers,
Simon.

I have a fiberglass fastback tank that was NOS, but I cleaned it and sealed it fifteen years ago (and that was with Kreem!) that is still going strong today. I would never use Kreem again as I believe that the Caswell epoxy is much better suited to fiberglass. I have seen some pretty ugly Kreem disasters. I can't explain why mine is still perfect. I beieve if properly cleaned and allowed to thoroughly cure there is no reason why the Caswell epoxy system should not be a permanent solution.

On the other hand if I had the choice between steel and fiberglass.....

If you decide to go with one of tne new steel tanks you need to make sure and pre fit before painting. The under side of the tank needs some work before they fit over the head steady area and the front tabs on my frame had to have some very slight filling to get the tank to sit down over them.

Just wanted to report back on my sealing of my fiberglass tank with Caswell, I was very careful in mixing it and followed the directions to the letter. I was a little worried about how long it took to set up but it was on the cool side. But I can say boy does it seem dry now, In the morning I checked the left over stuff and it set up perfect. This tank didn't have any leaks but I really want to use it because the steel reproduction tank does not have the same lines as the original. And Caswell says it is a permanent fix. I will report back in 5 or so years. As for the tank from Pakistan, I think that one will get the camo treatment. Should help hide the weak lines.