I need a diesel proof sealant

[Two Bit]

I have a 50 gallon aux. diesel tank in the bed of the truck. I installed a new fuel level sender unit in the top of it, (cut a 1 inch hole and 5 screw holes) and when it sloshes there is a slight leak of fuel onto the top of the tank (like a seep around the gasket and bolts). I need a good sealant to use to help the gasket stop this leak and subsequently to prevent rainwater from entering the tank. What is the best sealant? RTV? JB-WELD? ??? The tank has a vent line plus a prevent filler cap to stop high pressure buildup so there is little or no positive pressure inside. A friend gave me some special fuel resistant clear vasaline type stuff for sealing. He uses it on aircraft fuel fittings. It stays pliable. I used it and tightened the sender down as much as I dared. This slowed the leak but did not stop it. I'm not opposed to using something that hardens.
Thanks

[Two Bit]

I have a 50 gallon aux. diesel tank in the bed of the truck. I installed a new fuel level sender unit in the top of it, (cut a 1 inch hole and 5 screw holes) and when it sloshes there is a slight leak of fuel onto the top of the tank (like a seep around the gasket and bolts). I need a good sealant to use to help the gasket stop this leak and subsequently to prevent rainwater from entering the tank. What is the best sealant? RTV? JB-WELD? ??? The tank has a vent line plus a prevent filler cap to stop high pressure buildup so there is little or no positive pressure inside. A friend gave me some special fuel resistant clear vasaline type stuff for sealing. He uses it on aircraft fuel fittings. It stays pliable. I used it and tightened the sender down as much as I dared. This slowed the leak but did not stop it. I'm not opposed to using something that hardens.
Thanks

[CyberVet65]

Go over to http://www.thedieselstop.com
ask them there.
Chet

[Two Bit]

I have asked there also since I am also a member there, but everyone knows this is the best board for the best answers to all things related to RV's and tow vehicles.

[Gary RVRoamer]

Permatex Form a Gasket #2 is suitable for use with fuels and oils. #1 can be used with commn shop fluids and fuels too, but #2 is better for that application according to Permatex. RTV Silicone is not suitable for fuels, according to the Permatex website anyway.

But if you can get the area dry and clean once, almost any epoxy product that bonds to metal should do it. The problem would be to get all residual fuel oil off the surfaces first.

[Dougmyers]

If you can locate a good aircraft parts and supply place go in and ask them for PRC 1435 or maybe just order some from this link.

PR-1435 Quick Repair Fuel Tank Sealant
Description
PR-1435 is a quick repair, aircraft integral fuel tank sealant. It has a service temperature range from -75?F (-59?C) to 250?F (121?C), with intermittent excursions up to 275?F (135?C). This material is designed for sealing of fuel tanks and other aircraft fuselage sealing applications. The cured sealant maintains elastomeric properties after exposure to both jet fuel and aviation gas.

PR-1435 is a two part, dichromate cured polysulfide compound. The uncured material is suitable for application by extrusion gun or brush. It has excellent adhesion to common aircraft substrates when correctly primed with PR-148 Adhesion Promoter.

Technical Data Sheet for PR-1435

http://www.bergdahl.com/PR-1435.htm

[doc]

I believe Gary haS the simplest idea. Permatex has been taking care of ole boys working under shade trees down South for years. See no reason it would not work here. Make sure you get the oil resistant type.

[RustyJC]

Permatex #2 has been sealing threaded connections and gasketed joints in the oil field against hydrocarbons for many decades. All of the threaded connections for my truck's fuel pressure gauges are sealed with Permatex #2.

Rusty

[Two Bit]

Update and final; I used Permetex #2 over the weekend and have test driven it a few days with the fuel sloshing in the tank. So far no leaks or seeps have developed, looks like it is going to hold OK. Thanks everybody