Sonex Fuel Tank & Oops Fittings

[kevinh]

I think the idea to make tanks without the molded fittings is a great one. Would make the job easy.

Yep. I recently ordered my kit and it will be a bit of a hassle for me to to the same work you just did. It seems given the high rate of leaks with the molded in fittings that Sonex hasn't opted to do just what you describe. Over the next couple of years of building I'll have to decide if I'm going to go with the built in fittings and hope, or bite the bullet and do the mod preventatively.

[Bryan Cotton]

So on my initial leak check the only fitting that did not leak was the small fuel sender fitting. Ironically I did the worst job on that hole. Just goes to show that it is all about the O ring and its sealing surface. I am going to take out those two fittings because I don't want water trapped in there. I think on round 2 I will use air, because the inside of the fittings will stay dry. I can look for soap bubbles and torque the oops fittings until they are gone.

[Waiex 49]

Hi Bryan,

Nice job on the "oops" fittings.

You may want to consider using some locktite on the fittings.

I used locktite on mine, didn't want them to come loose while I was flying around!

Seems it is much easier to do these fittings while on the initial build.

Having to remove and replace the fuel tank to make these repairs is no fun.

[Bryan Cotton]

I thought I had a good wrench collection but my wrenches were either too thick or too small for the oops fitting. Also, I am not sure if they are SAE, metric, or whitworth. So, I made an oops fitting wrench out of 1/4" plate.

[WaiexN143NM]

Bryan,
And to everyone, the oops fittings I ordered from sonex have grooves machined on the inside the tank flange side. A green o ring on the 3/8 larger fitting and black o rings on the 1/8 fittings. The green o ring fits nicely in the groove, but the black o rings on the smaller fittings seem to large to fit and seal in the machined groove. Any one else notice this? They are too large to fit in the groove and then seal properly. Will measure and get some Viton o rings to fit.

WaiexN143NM
Michael RADTKE

[DCASonex]

Bryan,
And to everyone, the oops fittings I ordered from sonex have grooves machined on the inside the tank flange side. A green o ring on the 3/8 larger fitting and black o rings on the 1/8 fittings. The green o ring fits nicely in the groove, but the black o rings on the smaller fittings seem to large to fit and seal in the machined groove. Any one else notice this? They are too large to fit in the groove and then seal properly. Will measure and get some Viton o rings to fit.

WaiexN143NM
Michael RADTKE

Yes, had similar problem two years ago. At that time, Sonex just bought these off the shelf from another supplier, and had no knowledge of the O-ring size or their material. I replaced the O-rings on smaller fittings.

David A.

[WaiexN143NM]

Hi David,
Yep now i remember reading your post a couple years ago, thanks for the reminder. Bryan this could be part of your leak problem. Take one of the small fitting out and apart and size the o ring with the machined grove, u may find the o ring too big.

Cheers to everyone on this nations holiday memorial veterans weekend !

WaiexN143NM
Michael Radtke

[Klimek]

Bryan,
Not being nosy, but would it be better to check the fittings with a solvent
Or something like kerosene or the like. When I would complete a VW valve
I was trained to check the seating with kerosene. It will go where water
Won't. I think it has something to do with viscosity, surface tension or
The like. Some of you scientists / engineers would know.
Frank

[Bryan Cotton]

Frank,
I agree. A check with water is good because it is just water, and if the water leaks it is definitely no good. I am going to use compressed air and soapy water next.

[SonexEZ]

Hi David,
Yep now i remember reading your post a couple years ago, thanks for the reminder. Bryan this could be part of your leak problem. Take one of the small fitting out and apart and size the o ring with the machined grove, u may find the o ring too big.

Cheers to everyone on this nations holiday memorial veterans weekend !

WaiexN143NM
Michael Radtke

Hi I have a leak but its on the hex head right side of the fuel tank its not the oooppp fitting i have tried several things still seeps ,