John,
they both use washers.  The TEMP II sensor uses a copper crush washer; the
smaller gauge sender also uses a washer but it's not copper.

-Wes

On Sun, May 4, 2008 at 1:37 PM, John Reynolds <kayakjr@comcast.net> wrote:

> Can anyone tell me if the coolant gauge temperature sensor (in thermostat
> housing - not the level sensor in the expansion tank) uses an O-Ring?   I'
> can't tell if this sensor and it's cousin for the fuel injection make direct
> contact with coolant and need a o-ring of some sorts.
>
> John
>