what sealant to use on fuel sending unit gasket?

[tfret]

New fuel tank, everything fits like a glove. Except when they drilled and tapped the five holes for the sending unit, one hole is off center a good bit. This required me to "slot" the screw hole in the sending unit as well as the gasket. I'm concerned out fuel leakage. I'd like to seal it well with something but I've been told NOT to use silicon because it will disolve. What product should I use?

 

[fishrdan]

Re: what sealant to use on fuel sending unit gasket?

How about some pics? How far off was/is the screw. What material is the tank, aluminum?

Since the screws should have gaskets on them (to seal the screw to the sending unit), even if the tank and gasket have 1 screw hole a bit off, the gasket should still seal it off, the gasket crushes pretty good. It really depends on how far off the hole is.

If in doubt, JB weld a SS nut on the bottom side of that screw hole, so it fills in the imperfection and gives the screw something to bite into, instead of cracking the JBweld. Then use a SS machine screw for that hole. Gas is impervious to JBweld, but I wouldn't use it as a "Sealant

 

[Solittle]

Re: what sealant to use on fuel sending unit gasket?

Since the tank is not under pressure the only thing you need to seal for is leakage. The four screws will adequately secure the sending unit to the tank. For the buggered up hole I would use Marine Tex to fill the hole in the tank and the corresponding screw hole in the sender. When dry (Marine Tex dries like stainless steel) dab the mating surface and all screw holes with Permatex Form a Gasket.

 

[tschmidty]

Re: what sealant to use on fuel sending unit gasket?

There are a number of different products to seal it. I have used a flexible high-temp sealant from permatex on that sort of thing with good success.

 

[Art Bernard]

Re: what sealant to use on fuel sending unit gasket?

Use the same permatex sealant you'd use on a car's mechanical fuel pump.

Art

 

[metriccrescentwrench]

Re: what sealant to use on fuel sending unit gasket?

Except when they drilled and tapped the five holes for the sending unit, one hole is off center a good bit.

Don't ask me why but there is one and only one way to line up those holes for fuel sending units (yes, I found out the hard way). When there's a gasket involved that makes a hell of a lot of combinations to try, but it does eventually line up.