seal for H20 temp gauge sender on cylinder head?

[88regular]

Hello everyone,
I have a '64 series IIA 88" sold in North America which has a Smith's gauge for oil pressure and H2O temperature. The temp probe has female threads and attaches to the cylinder head just below the thermostat housing to an adapter with male threads which is screwed into the head. Is there a copper crush ring or other kind of seal between the two? Or are people just wrapping it with teflon tape? The fitting does not appear to be tapered as I would expect for a pipe thread. Without tape or a seal in there I can thread the probe on all the way until it bottoms out on the adapter in the head.
Thanks!

[o2batsea]

The sender adapter threads for the bulb are good old hardware store gas fitting 5/8-16. The adapter is (I think) either BSPT or NPT. Sooo the adapter you will want to wrap with teflon tape and run it in snug on the engine. Then the bulb nut you want that to bottom out on the adapter with no tape; should be a "jam" fit. These are all soft metal so don't over tighten or you'll be sorry.

[wrenchnsax]

Related question: (MIL-109) working from the inside out, head female threaded below thermo, copper bulb sending unit into head, a threaded aluminum knurled fitting into the head, the back of the bulb sending unit, a hex head brass fitting (looks like its the jam nut for the back of the bulb into the alum fitting), and last the protected wire headed for the gauge. The hex head backs off just fine, but the aluminum is now one piece with the bulb and wire. I don't know how I was able to disengage it when I started my valve job, but now I'm risking breakage trying to get more than one thread engaged into the head (I have to rotate the knurled alum fitting CCW, try to start the thread and hope I can get a full turn which probably won't be enough. So first, am I right that the alum fitting should be able turn without the bulb/wire turning; and if so, how to disengage without damaging the bulb/wire assembly (no WD-40 overnight didn't work)?

Thanks for your insight.

[mearstrae]

Try soaking (submerging in) in PB Blaster or (of all things...) Coca-Cola, at least overnight. It should loosen up.

'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S