Andrew Davies 3 Posted March 19, 2016 Share Posted March 19, 2016 Hi all, Thanks for your help last weekend. I'm now putting the fuel tank in, and having read that I should pressure test it before I fit it, I could do with some help. I submerged the tank in a bowl of water, and with two of the pipes blocked, blew into the other. There are some small bubbles escaping which appear to be coming from near to where one of the pipes exits the bung. I've tightened the screw as far as I dare and wondered whether I could use some silicon or something between the inner metal circle and the rubber bung? If not, any other tips? Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 19, 2016 Share Posted March 19, 2016 I think you have a faulty tank if correctly assembled. I don't think a bit of silicone is going to be a lasting fix, and a dodgy tank is potentially a broken plane after the dead stick. Take it apart, and see if you can find a fixable problem. Frustrating I know but a tank has to be right. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 19, 2016 Share Posted March 19, 2016 Tubes are a bad fit in the bung, replace the bung/tubes. John Quote Link to comment Share on other sites More sharing options...
Martin Whybrow Posted March 19, 2016 Share Posted March 19, 2016 Are the pipes plastic? If so, I had one and the pipes were really badly moulded and had no chance of sealing; I replaced them with new ones made from some alumium 1/8" tubing. Quote Link to comment Share on other sites More sharing options...
kc Posted March 19, 2016 Share Posted March 19, 2016 A faulty tank will just take all the joy out of flying - replace it or just the bung. Now that so many have gone over to electric flight there must be stacks of unused tanks around.......someone in your club must have a spare bung lying around. Quote Link to comment Share on other sites More sharing options...
Andrew Davies 3 Posted March 19, 2016 Author Share Posted March 19, 2016 I've tried two bungs and two sets of pipes. I broke one of the plastic pipes which came with the kit, and so bought a new set of copper pipes (and a new bung). I'll have another try tomorrow. I take it there should be NO bubbles at all, what sort of pressure does the exhaust put into the tank? Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 19, 2016 Share Posted March 19, 2016 Not a lot of pressure, but no bubbles. I normally check by sealing all but one pipe, and suck on the last pipe, and expect the vacuum on the tongue sealed pipe to stay vacuumed. Tiny leaks play havoc wth fuel/air mixture, and hence dead sticks. As I said earlier, the tank has to be perfect. Quote Link to comment Share on other sites More sharing options...
bert baker Posted March 19, 2016 Share Posted March 19, 2016 Have done the vacuum way but did find one day the pipe sealed itself under vac but opened up with pressure. Another one to watch for is split Clunk lines, but that's another story, Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted March 19, 2016 Share Posted March 19, 2016 The best test is to seal all pipes and submerge the tank in a bowl of hot tap water. Sounds as if you need a new tank. I prefer Radio active tanks myself. Quote Link to comment Share on other sites More sharing options...
Shaunie Posted March 19, 2016 Share Posted March 19, 2016 Pull the bung out and see if the inside of the neck has any moulding flash in it, if so trim it out and sand smooth if necessary. Shaunie. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted March 19, 2016 Share Posted March 19, 2016 We all know that a leaking tank can lead to a dead stick, and loss of a model. Get a decent SLEC tank from Blackburn Models, it will save your model Quote Link to comment Share on other sites More sharing options...
jrman Posted March 20, 2016 Share Posted March 20, 2016 Have you tried tightening the screw just a little more? Quote Link to comment Share on other sites More sharing options...
Former Member Posted March 20, 2016 Share Posted March 20, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
cymaz Posted March 20, 2016 Share Posted March 20, 2016 Posted by Percy Verance on 20/03/2016 07:30:47: A decent SLEC tank? Hopefully you don't mean one of those awful square things with the plastic inlets/outlets Denis? Dubro or Sullivan all the way for me........ Edited By Percy Verance on 20/03/2016 07:31:16 +1 Quote Link to comment Share on other sites More sharing options...
bert baker Posted March 20, 2016 Share Posted March 20, 2016 Have you overtightened the bung and split the neck. Quote Link to comment Share on other sites More sharing options...
Andrew Davies 3 Posted March 20, 2016 Author Share Posted March 20, 2016 I don't think so, it seems to be leaking from around one of the brass tubes rather from the neck. I'll have another go shortly and see how I get on. If not then I reckon I may need a new tank? Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted March 20, 2016 Share Posted March 20, 2016 Do yourself a favour and dump the ARTF tank - you might fudge it and get it sealed now, but as sure as eggs are eggs, it'll give you problems in the future. Go for a Dubro or Sullivan, there's just too much to risk for the sake of a few quid to get a reliable and well engineered tank. Quote Link to comment Share on other sites More sharing options...
Former Member Posted March 20, 2016 Share Posted March 20, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted March 20, 2016 Share Posted March 20, 2016 I've never used any of the tanks that have come with the ARTFs that I've had over the years (just remembered the exception being the one in a Great Planes ARF kit that was fine) but the Seagull and Vmar ones were hopeless. I've tried them and they've either leaked on test or the horrible bendy plastic tubes looked fit to break at any moment. I hacksaw off the tops and use them for brush cleaning etc - waste not, want not Quote Link to comment Share on other sites More sharing options...
Andrew Davies 3 Posted March 20, 2016 Author Share Posted March 20, 2016 Thanks guys, new tank it is then. Will go and get one tomorrow. Will do seven later instead. Cheers Quote Link to comment Share on other sites More sharing options...
Andrew Davies 3 Posted March 20, 2016 Author Share Posted March 20, 2016 Spellcheck!! Servos... Quote Link to comment Share on other sites More sharing options...
ASH. Posted March 20, 2016 Share Posted March 20, 2016 +1 for Dubro tanks. Artf tanks can work well too. With minute air bubbles you can sometimes just push/pull on the tubes a bit so rubber forms a better seal or tighten/slacken the centre screw if bubbles are coming from there. Putting on the final fuel tubing may also put a strain on the seals so best to check again. I also like to put fuel line clips on to ensure everything stays in place. They are fiddly and sharp so care has to be taken.I then wrap masking tape around the whole lot. Job done and it's fit and forget. It's a pain otherwise having to remove the tank to fix fuel supply/engine problems. Best to get it right first time! I also use the smallest tank possible for the engine to get a good 15 minute flight. No excess baggage! Quote Link to comment Share on other sites More sharing options...
cymaz Posted March 20, 2016 Share Posted March 20, 2016 Experience with a Dubro tank has taught me that the hole are slightly smaller that the brass tube. I slip the tube into the hole and push the pipe against a piece of wood. This effectively forces the tube to make its own hole giving a good tight seal. The other good thing with that make is that there is only two holes fully cut. The third is moly half cut, giving the option of a two or three line fuelling set up from one bung. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted March 20, 2016 Share Posted March 20, 2016 I pressure test tanks prior to fitting by sealing off two tubes with a piece of fuel tube . Then I pump air into the tank with a large syringe and clamp the pipe with a pair of forceps . If it stays pumped up for 1/2 hr or so then its ok . If not pump up again and dunk it in a bowl of water to trace the leak . Be careful when tightening the bung as the cheaper tanks can split on the seam as the bung expands or as is usually the case split at a later date soaking the moed with fuel . These are usually cheap tanks supplied with artfs and should be dumped . Better tanks have a brass ring that fits over the neck to stop it from splitting when tightened. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 20, 2016 Share Posted March 20, 2016 Posted by Peter Miller on 19/03/2016 20:55:13: The best test is to seal all pipes and submerge the tank in a bowl of hot tap water. Sounds as if you need a new tank. I prefer Radio active tanks myself. Why didn't I think of that, simples. Quote Link to comment Share on other sites More sharing options...
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