The fuel leak in my left wing tank that I thought I had fixed a year ago
has returned. I have tanks in each outer wing panel, 12 1/2 gal, and
after 14 years the gasket that secures the sender units to the tank
developed a very minor leak, just enough to require fixing. Last year I
removed the wing, pulled the fuel sender assembly, installed a new
gasket and re-installed the sender unit. Unfortunately the threads in
the 1/8" mounting plate stripped in one of the five holes. I tried
threaded inserts but they would not fit tight enough to prevent
rotation. I installed heli-coil inserts and the fix was marginal so I
added sealant around the bolt heads and that seemed to work. Well, one
year later and the leak is back. Here is a photo from last year. The
patch you see on the tank is from 15 years ago to repair a leak after
the first fill. It is the sender unit / gasket / mount plate that is
the problem. I'd like the break the pencil of the engineer that
designed an 1/8" mounting plate.
https://www.dropbox.com/s/7oomdcvvj7uo40r/image000000-1%20copy.jpg?dl=0
After the Gathering I will pull the wing again and attempt a permanent
repair. Problem? What will be a good fix? I could rotate the sender
slightly and drill 5 new holes and thread but an 1/8" mount was a crappy
method the first time. No access to inside of tank. Here is a VERY
ROUGH line drawing of the setup. Excuse my total lack of artistic talent
and lack of motivation to improve it.
https://www.dropbox.com/s/kh2f69fborks986/fuel%20leak%20001.jpg?dl=0
I'm considering having a friend make up a matching aluminum puck approx
1/2" thick, drill and thread mount holes that do not penetrate to the
tank, then epoxy or J.B. Weld the puck to the existing tank mount.
That would give excellent mounting pressure for the gasket and the only
hole to seal would be the center hole where the sensor probe enters the
tank. I'm not inclined to cut the old mount from the tank and start
over without having access to the inside of the tank and I'm not
inclined to open up the tank. I'm convinced I could get a good seal on
the puck, especially with a lip / joggle turned on the puck on the tank
side and then covered with several layers of glass / epoxy. I'm liking
this fix better the longer I consider it and making mental adjustments.
Opinions?
Larry Flesner
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