rick1 Posted January 18, 2007 Report Share Posted January 18, 2007 Do any of you old timers (like me ) have a slick new way to repair fiberglass gas tanks. I have a Bultaco Sherpa tank that is leaking along the lower seem and at two spots up near the frame head stock (looks like it was damage on either side by the handlebars). The tank was lined with a Kreem type liner product which obviously wasn't working. I managed to get all that out with an Acetone rinse. Fiberglass is a thermoset type product which means you can't add more fiberglass to it after is has set and get the same strength and bond as when it was orginally setup. So I am looking for info and suggestions that folks may have on repairing tanks maybe with some other type bonding agent. Any ideas / Advice? Quote Link to comment Share on other sites More sharing options...
muddytires Posted January 18, 2007 Report Share Posted January 18, 2007 I don't know where you are, but here in the U.S, POR-15 makes a tank sealer for fiberglass. The white kreem is used on metal tanks, so won't work. They say that an epoxy resin is more chemical resistant than the normal poly resin. But like you said it's probably best to find a tank sealer made for fiberglass rather than coating it again with more resin. Oh, and a tip for anyone using Kreem on metal tanks : Thin it down a little ,before pouring . I found out that the stuff was too thick to get into the nooks and crannys, and still leaked in the places it didn't reach. Quote Link to comment Share on other sites More sharing options...
shercomike Posted January 18, 2007 Report Share Posted January 18, 2007 I struggled with a leaking Bultaco tank for some years. I finally broke down and used a guy in Texas who advertises in the SMOG newsletter--James Enterprises, I think. He has a high tech approach to sealing the old crappy Spanish tanks. He puts epoxy in the tank and then rotates it for some days while it dries. He also did a stellar job of painting the outside including adding a few coats of clearcoat. It wasn't cheap, $250 if I remember, but it saved me a lot of time and hassle and gas fumes. In the UK, the fibreglass tanks were illegal for street use (trials bikes were/are street legal) and they were sold with aluminum or aluminium tanks. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted January 19, 2007 Report Share Posted January 19, 2007 Brushing epoxy works perfectly. It is thin enough to get it to coat everywhere inside and it takes hours to set so you can leave the tank to drain out and only a thin coating remains. It sticks great to old fibreglass if you clean out the premix properly. I cleaned my tanks out with turps, then thinners, then acetone and left them to dry fully overnight before the epoxy. Choose a bright day so you can see inside easily to see that you have coated everything. I put plasticene where I dont want the epoxy to stick ie like the cap thread. Brushing epoxy protects the fibreglass from the ethanol that is in some car fuels too. You should be able to buy it from boat shops and model aircraft shops. It cost me $40 for 500ml which is enough to do an M138 Alpina and an M49 Sherpa. If you do them all with the one mix, that would probably be enough to do three tanks. Only about 75ml stays inside the tank but you need to put about 250ml inside to start with to make sure everything gets coated. Quote Link to comment Share on other sites More sharing options...
twinnshock Posted January 19, 2007 Report Share Posted January 19, 2007 In the UK, the fibreglass tanks were illegal for street use (trials bikes were/are street legal) and they were sold with aluminum or aluminium tanks. Fiberglass tanks were not made illgal until the early 70's and this law was not made retrospective. So the sherpa fitted with the kit campion fiberglass tank or earlier has always been road legal in the UK. Bultaco did introduce the aluminium tank to get around this law and continued to supply aluminium tanks for the UK market long after introducing the plastic (polyprop?) tank for other markets. Stuart Quote Link to comment Share on other sites More sharing options...
dgshannon Posted July 27, 2008 Report Share Posted July 27, 2008 After a TON of research, the only product that seems to have any merit, for preventing the ethanol attack on fiberglass fuel tanks is made by Caswell Inc. gas tank sealer. Link: http://www.caswellplating.com/aids/epoxygas.htm In a post above, reference is made to "a guy in Texas who advertises in the SMOG newsletter--James Enterprises". His name is Ed James, and here is his website: http://www.edsbultaco.com/ After coming across various postings, on marine websites, discussing the failure of such products (POR15, KBS Coatings, Caswell, etc.) in fiberglass boat fuel tanks, I contacted Ed James to gain his insight. In the end, the Caswell sealer is the product of choice. But, the key is in the preparation for sealing, and then the sealing process itself. Here is where Ed is a pro worth paying for his service. He has fine tuned the process, and developed machinery for keeping the tank rotating across multiple axis, for at least an 8 hour period. My tanks (2 Cota 247 bodies) are headed off to Ed, so he can work his magic. I will let you know how it comes out. Quote Link to comment Share on other sites More sharing options...
swooshdave Posted July 27, 2008 Report Share Posted July 27, 2008 After multiple failures with POR-15 (in it's defense it's not made for fiberglass specifically) and the only tank that is holding up has Caswells in it, I concur with your findings. I'm currently draining the tank(s) after each use (if they are going to sit for more than a couple days). Quote Link to comment Share on other sites More sharing options...
fsb Posted July 27, 2008 Report Share Posted July 27, 2008 In germany I've found the "Kreem wei Quote Link to comment Share on other sites More sharing options...
swooshdave Posted July 28, 2008 Report Share Posted July 28, 2008 I wouldn't suggest Kreem to my worse enemy. Quote Link to comment Share on other sites More sharing options...
fsb Posted July 28, 2008 Report Share Posted July 28, 2008 I wouldn't suggest Kreem to my worse enemy. Ok, I understand. Felix Quote Link to comment Share on other sites More sharing options...
motovintage Posted July 28, 2008 Report Share Posted July 28, 2008 the caswell coating is the only one I would recomend Quote Link to comment Share on other sites More sharing options...
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