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Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Sat Nov 04, 2023 11:09 pm
by BRS
Moving at a snails pace. Yesterday, Davids tool showed up. Today I spent a small amount of time trying to get the tool in place but to no avail. Seems this flange may be slightly tapered making it hard to get the tool lined up. That flange that is maybe 3/4" or more deep (see pic). I'm thinking I'll have to get a knife and remove part of this before I can get the sanding tool in place. Is this flange common? I'll try again to attack it on Monday.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Mon Nov 06, 2023 9:31 am
by DCASonex
It does look to have a significant tilt to it, as mentioned before, rotational molded tanks are like snow flakes, no two are alike. Can you post or email a photo with the toll partly in place to get a better idea of the extent of the problem ?

David A.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Mon Nov 06, 2023 10:19 pm
by BRS
Not at an angle. It's the wide angle lens on my phone.
Question: Was I supposed to use an Xacto knife and remove as much as that flange before using the sanding tool? I was thinking/tried to use the tool to remove the flange.

Later I found a small dremel circular saw and cut about 1/2" off then managed to get the tool in place. So far it doesn't seem to be removing any plastic. I'll attack it again tomorrow. Something I didn't read but figured out was that after using the tool it would be handy to still have the wire avialable to remove the tool. My solution, remove the two washers (pictured) and carefully slide the wire into the end of the tool and let the tool rotate around the wire.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Tue Nov 07, 2023 11:51 am
by DCASonex
Thanks for the photo. I would remove your fuel level sensor just to make sure it does not get damaged.

Usual method I used to remove the tool was to feed the wire into the tool and back up toward inlet opening.

Key to removing material with that tool is relatively high pressure and very slow speed . Need to cut the plastic not melt it. It is not fast but all you need to do is make a flat surface, parallel to the outside surface, for the O ring to seal on. Make sure the grit is not clogged. If you need more grit, that open weave material is it is the stuff used for sanding drywall joints it seems to resist clogging, but other coarse sandpapers will also work..

David A.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Tue Nov 07, 2023 2:57 pm
by BRS
DCASonex wrote:Thanks for the photo. I would remove your fuel level sensor just to make sure it does not get damaged....

David A.


Ha, I told myself that (remove sensor) several times. Yet the thought of disturbing the insert and having to install another OOPs fitting kept me from doing that. Yesterday after taking the above picture I couldn't remove the tool as the fuel-level-sensor was in the way. Scratching my head as to how I got the tool in place and removed before one already without an issue.

As they say... Good judgement comes from bad judgement. ;-)

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Wed Nov 08, 2023 9:31 am
by DCASonex
What concerned me about the fuel level sensor was that you mentioned leaving the wire threaded through the tool while using it, if the wire should snag on the tool or the drill chuck holding it, it would thrash about and very likely damage that sensor.

Re-reading the previous post of yours, it might not have been clear that you do not need to remove the mound of plastic that used to surround the molded in fitting, just flatten the inside surface enough to give the O-ring a surface to seal on. If the oops fitting is not long enough to put on a fiber washer and thread the nut the on outside, then you will have to grind it down a bit.

David A.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Wed Nov 08, 2023 11:59 am
by BRS
DCASonex wrote:...
Re-reading the previous post of yours, it might not have been clear that you do not need to remove the mound of plastic that used to surround the molded in fitting, just flatten the inside surface enough to give the O-ring a surface to seal on. If the oops fitting is not long enough to put on a fiber washer and thread the nut the on outside, then you will have to grind it down a bit.
David A.


David! Oh wow that is huge information. Yes, I had understood that I needed to sand the "mound" down to a smooth tank wall. Sanding/grinding has been going frustratingly slow but you are saying I've likely done plenty of that. Now I just hope I have the 'mound' true to the outside wall. That 'mound' neck is about " fro1/2" fromm the outer wall at the moment.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Tue Nov 14, 2023 11:27 pm
by BRS
The OOPS saga continues but I feel there is light at the end of the tunnel. I purchased an endoscope with a loooong flexible shaft. It enabled me to look into the tank from the outside while I was upside down under the pannel. So hopefully these pictures will be of some use to someone else. They would have helped me.

As you can see I ended up removing more material than needed. Tomorrow I'll try to install the OOPS fitting and check for leaks.
Q. How tight have you folks been turning down the nut? Are the O-rings visibly flat?
Q. How smooth does that neck need to be. I want to polish it but can't.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Wed Nov 15, 2023 10:27 am
by Bryan Cotton
Not sure how tight I made the fitting. I did leak check it though. Made an adapter to put a tire valve stem on one fitting. On another fitting I secured a balloon to it for use as an indicator and a fuse. Pictures on my Photo Album thread probably towards the middle.

Re: Sonex Fuel Tank & Oops Fittings

PostPosted: Sun Nov 19, 2023 4:24 pm
by tps8903
How many and which oops fitting do I require to replace them all?

I have a weeping leak out of the main fitting, not enough to ever Drip, but the blue dye is obviously on the outside of the tank.

I figure if I'm taking the tank out I'm going to replace them all.