diesel tank sealants

[rugila]

I have a 3 inch hole for a float-type sender in the aft end of my diesel fuel tank. Stainless steel tank.

The flange sealant that was there, put on before I bought the boat, now leaks. Result that diesel drips past the flange and finishes up in the bilges.

I've tried looking around for the best replacement sealant (gasket eliminator sort of thing) but hard to find one specifically resistant to diesel fuel.

I'm looking for ideas. Any suggestions as to best stuff to use?

[JimsCAL]

The usual sealant to replace (or use with) a gasket is Permatex. There are a number of types, and I am sure one is suitable for diesel fuel.

[sailingdog]

You might try a RTV silicone sealant. Many are highly fuel/oil resistant and should work for your application.

[timebandit]

Permatex # 2 works for oil and gas, no waiting.
DO NOT USE #1 unless you never want to take it apart.
To clean up afterwards use alchol.

[MidLandOne]

You might like to also look at hylomar-usa.com (sorry can't insert a link as apparantly I need a few more posts first ).

I and others have used it exposed to diesel - very effective, available in small quantities, and a pretty blue color to boot . I've found it in auto type supplies shoppes but that outside of USA.

[jones2r]

Permatex/LocTite makes an Ultra Blue RTV sealant that stands up to about anything (fuel,heat,etc.). Should be available at any of the chain auto stores. Follow the instructions for permanence.

[dennisvetter]

A friend of mine has the same problem (caused by a "professional" who polished his fuel and the reattached the flange on the sending unit with wood screws and polysulfide sealant). His tank is some type of polypropylene. Will the sealants mentioned work well on that tank as well?
Many Thanks
Dennis

[SteveInMD]

I use this stuff...

Gasoila Soft-Set Thread Sealant with Teflon

Gasoila Soft-Set Thread Sealant with Teflon

[sailingdog]

Polypropylene is a tough plastic to get much of anything to adhere to. A compression type gasket would probably be better.

[dennisvetter]

Sailingdog,

Thanks for your response! I don't think I need, or even want, the sending unit to attach to the tank ... I just need to be sure it's well sealed. What's happening is that when he tops up his tank, the fuel in the filler hose leaks at the sending unit. I'm not very experienced with diesel fuel fittings other than to know that it seems to be very good at finding it's way past anything but a perfect seal. My friends live on their boat, have some health issues already so the last thing they need is to be inhaling any diesel fumes from the bilge and, of course, the potential for it to be pumped overboard is one we want to avoid at all costs. So I really want to be sure I get this right the first time.

So my thought was that some form of sealant might help the gasket which came with the sending unit form a better seal ... e.g. "Coats pre-cut gaskets to increase reliability". Further, there are some imperfections around the top of the tank where the sending unit fits thanks to the nimnul (quote unquote "professional") who removed the sending unit to polish his fuel and reattached it with wood screws into the tank itself. Am I being overly zealous about this? i.e. should I just attach the unit with the precut gasket provided and see if it leaks?

Thanks again,
Dennis