Wayne.B wrote:
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.

Teflon tape is a No-No because if it gets in the injection pump you have
killed the engine. Good reason to ban its general use in the workshop
if your staff aren't the brightest, but as long as you don't use it down
stream of the final filter and are intelligent about not over applying
it, or using it on inappropriate joint types so you aren't getting
chunks breaking loose and blocking lines, no problem. I usually reach
for the Gastite and the yellow reel Teflon Gas tape.

The OP might be well served with a *very thin* smear of Hermitite Red on
his inspection port gasket. Put a fuel sender in with that on its
neoprene gasket 3 years ago with bolts into tapped holes from the
inside with fibre washers under the heads, and washers and nylocs on
the resulting studs. Absolutely no weepage to date

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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