M

Mark Jackson

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I have been trying to test my fuel tanks for a month now. Pretty sure the tanks themselves don't leak. But I have been unsuccessful in sealing the test fittings (see attached photo.) The leaks seem to be around the threads. Any ideas on how to seel these. I have tried tape, plumbers putty, and wax.

At whit's end.

6s3pkw.jpg
 
It looks like the leak is coming from the Jam Nut that keeps the fitting on the tank. If it is, you need Pro-Seal on the fitting.

IF the leak is coming from the cap, try a "Copper Conical Seal" between the cap and fitting. I use a Copper Conical Seal everywhere I have a Steel to Steel flare connection.

If you have any "Bakers Seal" or "Tite Seal" that also MAY work. I do not like using any kind of sealant on flare fittings. If you use any for pressure testing, make sure you get it cleaned off before doing the final tube mate. Sealant used on this flare fitting could end up causing a fuel blockage down stream in the future.
 
seal

I made two fittings for the vent with 1/4" tube. They are about 4" long with a 90 degree bend. The plastic tubing fits over the end with a hose clamp. I used the same B nuts and sleeves as the vent line from the kit and bought additional for replacement.
If you didn't torque the cap on the fuel line, it might be the leak. I torqued all the test fittings on mine to minimum and they held fine.
There are pictures on the tank page of my blog.
 
This is a bit of a problem. I just went through this on my second tank a few days ago. For the fuel line I used a few wraps of Teflon tape and that fixed that leak. I had a balloon installed on my vent line. It looks like you are using the alternate approach. With the balloon method I first put a couple of wraps of duct tape on the vent fitting making sure that it didn't go down onto the conical section of the fitting. Then I installed the balloon over the taped area. Then I put another wrap of duct tape on the balloon in the fitting area. I then used safety wire and tightened it down to make the seal. I put two sets of wire down just to be sure. Seemed to work pretty well.

The first time I did this I was fighting the same problem that you are. I seemed to have fixed the leak around the vent fitting. I kept checking it and finally I wandered off to do something else and I left the garage door open. I think the wind must have blown the balloon into the end of the safety wire and it popped. That was after I had checked in after 2 hours. Finally I did manage to get through a 24 hour test.
 
Well, finally got the tubes sealed and it turns out that the tanks do have two large leaks around rivets on the back seams. Appears that the sealant didn't do well when the back bulkhead was slid into place. I am going to cut two round holes in the back and reseal the seams, then close the holes using the same plates used on the round fuel level gauge hole.

Never thought I would be happy to find my tanks leaking but now can get it fixed :)

Mark Jackson
 
Mark Jackson said:
Well, finally got the tubes sealed and it turns out that the tanks do have two large leaks around rivets on the back seams. Appears that the sealant didn't do well when the back bulkhead was slid into place. I am going to cut two round holes in the back and reseal the seams, then close the holes using the same plates used on the round fuel level gauge hole.

Never thought I would be happy to find my tanks leaking but now can get it fixed :)

Mark Jackson
Click to expand...

Might be worthwile to just fix the two rivets and see if that takes care of it. That's what I did on the only leak I could find (baffle seam, like yours):
FP20012013A00057.jpg
 
I think the instructions over state the amount of caution that is required for using too much sealant on the baffle. This resulted in a leak in my first tank and many others it appears from reading this forum. By my second tank I realized the mistake that I had made on the first tank, used more sealant and didn't have any problems.

Looks like you are on the road now to finishing your tanks. I can tell you it is a great feeling to have that behind you.
 
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