TRex 700 Fuel Tank Bung

[Steve]

The centre tank bung (the solid blank one) on my 700 is leaking like a sieve and I don't think you can buy them on their own without buying a whole tank, which is a bit of a pain.

Is there an alternative supply, can they be bought alone, is there a decent way to seal it up, or does any kind soul have one kicking around that they could send my way if I were to grease their palm with PayPal?

Engine is a YS so it's a pressurised system and I don't really want it to go pop with a lack-of-pressure lean run.

[jamiem]

Mine leaked from new, I found an o-ring in my spares that was a perfect fit for the inside of the tank hole. Put the o-ring over the grommet, then push the grommet in, and then peel back the edges of the grommet and make sure the o-ring has gone in to the hole to seal it. Works a treat for me, and has been like it for a few gallons now.

[bish]

A little silicone sealant around the bung works for me not sure why they need two holes its just asking for trouble IMO

[Steve]

A little silicone sealant around the bung works for me not sure why they need two holes its just asking for trouble IMO

Thanks

I did that maybe 20 flights ago and it's started leaking again already which is why I'm considering a new bung this time around.

[bish]

I always keep my tank fueled up not sure if it makes a difference to the bung but it has stopped my clunk lines perishing and falling off something to do with the exhaust gases in the tank after a flight rotting the silicone.

[Steve]

I always keep my tank fueled up not sure if it makes a difference to the bung but it has stopped my clunk lines perishing and falling off something to do with the exhaust gases in the tank after a flight rotting the silicone.

I hear what you're saying, but the current bung has lasted for over 2.5 years before it started playing up even when stored with an empty exhaust gas tank. Just seems a bit OTT to buy a whole new tank for the sake of the bung

[bish]

I guess if its lasted two and a half years then it ows you nothing and a tenner on a new tank is money well spent IMO

[Nick B]

Black pond silicone dries like the bungs material,sticks sh1t to blankets!.....dont get it on yer fingers!

innotec adheseal 50ml | eBay

[Rctintin]

I used the small Futaba servo wheel disc, slightly trimmed down in diameter, and threaded it to M4 in the centre. Then a M4 Stainless bolt with a penny washer on the outside of the bung, and then tightened with the servo disc on the inside. This squashes the bung in the hole, and I have had no leaks with a YS for almost 100 flights.

[Steve]

I used the small Futaba servo wheel disc, slightly trimmed down in diameter, and threaded it to M4 in the centre. Then a M4 Stainless bolt with a penny washer on the outside of the bung, and then tightened with the servo disc on the inside. This squashes the bung in the hole, and I have had no leaks with a YS for almost 100 flights.

Now that's a proper RC modelling engineering solution. Thanks.

[trexsteve700]

I have one spare if your still after it.
Just send address.
if your worried at all as im not well known ask around ive sent parts to a few people on here.
Steve




(sorry ive tidied up my workshop and now i cant find it. youll be the first to know when i do)

[Steve]

I have one spare if your still after it.
Just send address.
if your worried at all as im not well known ask around ive sent parts to a few people on here.
Steve


(sorry ive tidied up my workshop and now i cant find it. youll be the first to know when i do)

Thanks for the offer. I've just fitted a bolt through with servo disc, big wide washer, M3 cap bolt and a nut on the inside like Rob suggested. Pulled up great. Hope to see how it goes this afternoon.

[Steve]

Works a treat. Hopefully it will last. Thanks RCT.

[Si_B]

I'm so glad I search for this before buying a new tank/bung. Maidened my 700N today and fuel was leaking badly from the bung so only did a couple of running in flights. What a great solution..........this is what this forum is about.

Thanks for the fix.

[gorber]

I've just bought a 700 to build and will do this mod from the beginning.

How do you stop the nut from turning inside the tank when tightening the bolt?