On Mon, 5 Oct 2009 06:49:06 -0700 (PDT), RichH
wrote:

On Oct 4, 10:45*pm, matt_colie wrote:
Tom Dacon wrote:
What's your favorite diesel-resistant gasket sealant?

*This is for the nitrile gasket on a clean-out port on the top ofa small diesel fuel tank.
I wouldn't mind something that worked well for pipe threads, too.

Thanks,
Tom Dacon

Tom,
Why do you think it needs a sealant in addition to the gasket.
If you are having a distinct problem with the assembly,
there may be some other issue here.
Matt

Most threaded connections is a fuel system shouldnt ever need gaskets,
sealants, etc. Compression fittings, double flared fittings, etc.
are *dry* metal to metal 'ring sealed', and the 'threads' on these are
ONLY to apply force to the rings seal (compression faces). So, if you
need to seal such fitting with goo/glop/dope, etc. then you have a BAD
fitting or a fitting that is worn-out .... and you should replace the
fitting in its entirety.

Compression fittings are designed for 'one time tighten only' and if
you need to open and reconnect you 'should' cut off the tubing area
that the 'compression ferrule' fits and put the compression ferrule
back onto 'uncompressed' (copper) tube; copper tube deforms under
these ferrules and you 'should' always cut off any part of the tube
that WAS previously compressed.

Double flared fittings can be opened/retightened, etc. many times;
and, should be the 'choice' for boat installations.

That's fine for gasoline engines but many large diesels and their
external filtration systems used ordinary pipe threads. Diesel
mechanics routinely use something like blue Permatex goop to seal the
pipe threads. Supposedly teflon tape is a big no-no with diesel.