Sealant for fuel tank.

[Kalinka1]

Greetings all.
had to open my fiberglass diesel tank. Now have to reseal it. What have you used that works and will allow me to open it again.
Thanks Noel.

[Scubaseas]

Buna-N gasket material. Permatex Ultra Black would also work. Viton Flouroelastomer is good but expensive. Define reseal. Do you have an access plate or how did you open it?

[Kalinka1]

Thanks for the info. I have two plates on the top of the tank that I had to open to clean the tank. Now need to put them back on and seal them So need something that the diesel won't affect. Tank is 1/8 fibreglass.

[Scubaseas]

Permatex Ultra Black should work OK. Do not tighten all the way. Just snug it up then come back 24 hours later and go another 1/4 turn on the bolt or screw.

If you want the best way to do it IMHO would be to use gasket material like Buna-N sheet. It's reusable and looks better. Grainger's. McMaster-Carr or your local FLAP store should have some.

[Capt Clark]

Why not install a sealable lid since you may want to open it again?

https://www.agrisupply.com/hinged-li...iABEgLOF_D_BwE

[Capt Clark]

Here’s probably a better one….

https://marinesan.com/holding-tank-c...SABEgJ3sPD_BwE

[jamhass]

Methinks he already has a removable hatch. He just wants to seal it, and any diesel-compatible sheet gasket will work fine. Liquids and gels (RTVs etc) need to be checked for compatibility, but most are likely fine. In addition, if one is judicious in application (minimizing squeeze-out) nearly any FG-compatible (removable) sealant is likely just fine, as there should be nearly zero exposure of the sealant to diesel. Finally, one way to ensure that the hatch can be removed later is to first coat (very lightly) both mating surfaces with a compatible release agent (wax, oil, grease etc) before adding the sealant.

[Kalinka1]

Thanks all.