Sonex fuel tank revision

[aferddaberts]

Well Well Well, so nobody has even given my suggestion a try, which I submitted about a week ago. So go ahead, keep on trying Hot Glue, which won't even stick to glass, (Super Glue does,) and what other ideas you guys can come up with. According to the comments from many of you with leaking and weeping fuel connections, nothing you try works.
Super Glue may not work for you but it should be worth a try.

AL Roberts

[Darick]

I'm installing the oops fitting before I install my tank...what a pain! Trying to remove the high ridge inside the tank by just using an exacto knife is ...well let's just say it is an unsatisfactory method. To get a flat surface on the inside for the O-ring to seat on, can only be accomplished by inserting a tool like a dremel tool, with a cut off tool being used.
This is the cutting tool I used. I haven't done any leak tests yet so I don't know how successful it will be.

The scrap piece of aluminum is just keep the Dremel tool at the correct depth.

The diameter of the cutting tool is small enough to insert into the hole but I don't know if the flat area it has cut off, will be a big enough diameter for the fitting. I'm unhappy with this procedure since you really can't see the end result and the only way to confirm a tight seal is of course is to do a leak test.

This view is looking into the largest hole to one of the smaller holes which I just finished cutting the flange. You can't really see what's happening and is a lot of trial and error cutting. Quite an unsatisfactory way of making a leak proof job.

[Waiex 49]

Hi Darick,

Having replaced the defective fittings in my fuel tank I can tell you the Sonex "instructions" are poorly written. It is some sort of sick and twisted joke when they recommend removing the internal ridge of plastic with an exacto knife. It is pretty difficult to cut that plastic with an exacto knife, and you won't get the flat, smooth surface you want for those o-rings to seal.

The good gentleman who posts on this forum under the handle "DCASonex" created some very special tools that do a wonderful job of removing the ridge on the inside of the tank. I was going through what you are experiencing and thought I was at a dead end until he lent me those tools. You might want to look him up and see if you might borrow the tools. I posted the entire "oops" fitting repair (with photos) to my web page. Photos of the tools can be found there. www.mykitlog.com/donbowen

Changing out these fittings is a certain form of "reality check" that will cure you of any addiction to Wisconsin cool aid. If I were building up a new Sonex I would light the plastic gas tank on fire and dance around it while it burned. Then I would fabricate a set of wing tanks!

Good luck with your "oops" fittings,

Waiex 49

[Bryan Cotton]

Definitely borrow David's tool. I wrote a post on it. It was awesome.

Edit: here was my input on the subject:
viewtopic.php?f=33&t=1916&start=40

I think I had some info on my build thread too.

[DCASonex]

Last I knew, those tools were lent to someone out in the Chicago area and advised that they could be contributed to the Sonex foundation tool lending collection.

David A.

[Sonex1517]

I do have David's fuel tank tool - if anyone needs it drop me a note.


Robbie Culver
Sonex 1517
Chicagoland
N1517S

[Darick]

Don Bowen's kitlog website is an excellent review before starting the oops fitting installation. http://www.mykitlog.com/donbowen