Until I got my '86 Diesel DoubleCab, I had never had a coolant level sensor on
the coolant expansion tank.

Now it appears I am leaking coolant around the sensor at the top of the
expansion tank.  Is this a common problem?  Does this indicate a bad o-ring?
sensor? expansion tank?  If it is just the o-ring (as I hope), is repair as
simple as replacing and screwing the sensor in hand tight?  Is there a call for
a thread sealer?  Should I replace the sensor while I have it out (although the
current one seems to work fine)?  Bentley shows the separate parts, but is mum
on reassembly and torques.  Any suggestions are appreciated!

Maynard Southard  (OvO) '79
'86 Double Cab Diesel "Col. Potter"
'82 Westy Diesel "Reinhardt"
'82 Vanagon GL Diesel "Sluggo"
'93 EV GL "Klinger"
'00 Golf GLS TDI "WooHoo"
'84 Jetta GL TD "Donor"