Sealing Fuel Sender Unit

[danboy]

Long story short, I need to replace my fuel sender units after I finished constructing the tanks. Those of you that have done QB wings, how did you seal the sender unit? Squirt a little pro-seal in each nutplate and then seal the head of each screw? I'm thinking that would do it...

[Auburntsts]

I don't have QB wings but a few months ago I had to pull a sender to trouble shoot an issue. For the re-install I used a fuel appropriate Permatex gasket maker from a local auto parts store. I simply put bead down around the access and over the screw holes then reinstalled the rubber gasket and sender. No leaks or issues since I reinstalled it. YMMV....

[Planecrazy232]

I recently replaced my sending units in my 6A. I don't trust gaskets or permatex immersed in fuel. I Prosealed mine in place without gaskets, Proseal on screw threads and a blob over each screw. If I need to get it apart I'll deal with it at that time.

[ERushing]

If you're putting a new float sender in, you will probably want to adjust the floats so that they hit the top and bottom of the tank. You can do that a couple ways.

1) Initially, I was able to look through the fuel outflow hole and the vent hole to determine whether the float was hitting the top and bottom and if it cleared all the structural elements and vent line. (Drop a string in through the fuel drain and tie it onto the float to raise and lower it.) This method resulted in a lot of insert/ remove cycles.

2) The alternative is to cut a access panel in the back of the tank. I ended up doing this anyway for another mistake. It makes adjusting the float a piece of cake. Vans sells a fuel-tank repair kit that makes this a pretty easy proposition.



But to answer your first question - Yes just put some pro-seal on the screws and on the inner surface of the float plate. You might want to order some socket head screws which make tightening a lot easier. And if you ever have to make a repair, they will make loosening much easier than phillips head screws!

[Wyzepilot]

I used an ohms meter to test the sender and make sure that the float was against the top and bottom of the wing at the senders min and max read out respectively.

To seal I discarded the rubber gasket as per Vans (although that has been debated on this site) and used pro-seal just as Eric described above. I haven't put fuel in it yet however it did pass a leak test with no problem.
Dave

[219PB]

Vans recommends sealing with ProSeal. This is what is on the 14's instruction:

Discard the gasket supplied with the fuel level sender.

Apply a 1/16" thick layer of sealant to the area of the rib where the fuel level sender will be installed.

Place the fuel level sender in tis position on the rib but do not push it down into its "bed" of sealant.

Start a screw into each hole in the fuel level sender. Note that a lock wash is installed under the head of one of the screws. This should be free of sealant as much as possible for a good electrical ground connection.

Evenly and progressively tighten the screws just enough to cause sealant to bulge evenly from underneath the perimeter of the sender plate.

When finished, there should be a minimum 1/32" layer of sealant between the rib and the sender.

Leaving a thickness of sealant is important; should the sender ever need to be removed, it allows sufficient gap for a blade to be inserted between the sender and the rib to cut the bond.

Check for continuity between the ground plate on the Fuel Level Sender and the fuel tank skin using a multimeter.

[danboy]

That all makes sense; however, I just looked at the fuel tank section in the manual and it doesn't say "discard the supplied rubber gasket" -anywhere. Am I missing something??

[ERushing]

I believe it actually says it in the documentation that comes with the sender.

[Wyzepilot]

I called Vans for clarification when I was sealing mine and they told me to discard it.

[AAflyer]

Just a thought...I put my iPhone inside the tank with the video running, then screwed the plate mostly on, and moved the sender up and down with a wire slid through a small crack left in the slightly loose plate. Am pretty sure I got a good "bend", after looking at the video.