brucey Posted September 3, 2011 Report Share Posted September 3, 2011 Hi, After running my newly built Cub for around 8 hours, it has developed a pin hole in the new Vinylester petrol tank. I drain the fuel after every use but I noticed petrol dripping from a small (2mm diam) blister on the inside section near the bottom(where it hangs over the Oil in the frame top oil tank tube). I'm assuming it has a pin hole that has leaked into the gel coat causing the blister. To be honest, I have a feeling the blister was always there and I may have popped it whilst cleaning the tank! My thought is to buy some 2 part 'chemical metal' putty, gouge out the blister and make a small counter sunk hole, then slap the filler in the hole. I'm assuming polyester glassfibre resin or normal 2 part epoxy (araldite) will not put up with the ethanol in modern petrol. Has anyone else had similar problems and found a good repair method? I wish I had paid the extra and bought an ally tank now! Bruce. Quote Link to comment Share on other sites More sharing options...
bultaco49 Posted September 4, 2011 Report Share Posted September 4, 2011 Hi If you do a search on this forum or on the internet generally for fibreglass tanks and enthanol, modern fuels and fibreglass tanks etc you will see that the ethanol content (and some other additives) is causing major problems for those that store fuel in fibreglass. Ethanol has only been introduced relatively recently to pump fuels so its a new problem. I first encountered this problem on my Bultaco Sherpa and subsequently on my Alpina also. Both have fibreglass tanks. As far as I am concerned there is only one remedy that works and that is an internal two part tank sealer from Caswell Europe. You can find their stockist via an internet search. If you try any other cheaper alternative phone the producer and ask directly if the sealer is suitable for fibreglass tanks. Most are not and are aimed at sealing steel tanks and will not bond to fibreglass but fail to mention this in their blurb. Once used they are a nightmare to get out. Its important the tank is cleaned out properly before using sealer. Some people recommend acetone but this will immediately eat any paint it comes into contact with and will also attack the fibreglass if left in too long. I use a strong alkaline solution such as Marine Clean which will do the job but must be rinsed out with water and the water completely dried out of the tank. I have sealed all my Bultaco's and my Historic Kart tanks with Caswell and have had no blistering, delaminating or leakege. I sealed the Sherpa tank six years ago. Tim Quote Link to comment Share on other sites More sharing options...
bigshineybike Posted September 5, 2011 Report Share Posted September 5, 2011 There is an artical in last moths Vintage motorcycle club news letter regarding tank sealers. It seems that the new higher levels of bio fuel in pump petrol is having an effect on older tank sealers. bearing in mind the awful problems getting the wrong sealant out you should hang back on any solution that worked 6 years ago. I have taken to emptying my fibreglass Montesa tank after every outing. This ethanol thing is quite worrying for anyone with any machine (including lawnmowers and boats etc) built prior to the past few years. Ill try to summarise that artical soon. Quote Link to comment Share on other sites More sharing options...
brucey Posted September 6, 2011 Author Report Share Posted September 6, 2011 Bultaco & Bigshiney, thanks for your replies. My tank is slightly different to yours in that it was made less than a year ago in Vinylester rather than Polyester resin. This should give it the required resistance against ethonol. I used Vinylester products when I worked in the papermaking industry a few years ago and can vouch for there resistance to quite severe chemicals. I counter sunk holes where the bubbles had appeared and filled them with 'tank repair filler' purchased from Halfrouds(which included petrol tanks in the blurb). I waited 12 hours filled it up with petrol and watched it seep through the filler! (it went soft!) I have now removed that filler and repeated the operation but have used epoxy putty this time. I wait with baited breath to test it! If this is successful, I will also consider applying a sealant to the inside of the tank as I still believe I'm 'not out of the woods' yet! Has anyone got a decent Ally Cub Trials Tank spare? I may have to save up my pennies and contact Terry Weedy! life is too short. Bruce. Quote Link to comment Share on other sites More sharing options...
bultaco49 Posted September 6, 2011 Report Share Posted September 6, 2011 Hi Brucey I don't think any of the vinyl ester resin producers or manufacturers of products using vinyl ester will guarentee their products as resistant to ethanol(which is the 'bio' element current unleaded). If you use your fibreglass Cub tank with pump unleaded you should line it with a product that does guarentee ethanol resistance as not only does ethanol dissolve fibreglass, the gunk it turns into will clog up carb jets and galleries. And just for good measure, drain the tank anyway when not in use as Bigshiney suggests. Tim Quote Link to comment Share on other sites More sharing options...
brucey Posted September 7, 2011 Author Report Share Posted September 7, 2011 Tim, Thanks for the information. After looking it up, the Caswell treatment appears to be a good solution. I will also try to contact the guy who manufactured the tank for his comments. It might be a goog idea if he included the Caswell treatment as an option on new tanks because he would get the required 'economies of scale' to keep the price down. I tested my tank for a couple of hours last night and the epoxy putty seems to be holding up well. The 'Plastic Padding Petrol Tank Sealer' failed almost immediately when tested! Bruce. Quote Link to comment Share on other sites More sharing options...
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