...for a copper/asbestos crush washer.
8 and 10 TPI - 67 degrees
12 and 14 TPI - 90 degrees
16, 18 and 20 TPI - 135 degrees
24 and 28 TPI - 180 degrees
The degrees number is the amount of "turn" after contact, with lubricated threads. The unbroken surface of the crush washer should be against the part being tightened.
I think the temp sensor is a 18 TPI thread, but measure it... If so, 3/8 of a turn (135 degrees) might be better...
Printing this page and keeping it in your workshop is probably worth it...
http://i644.photobucket.com/albums/u...la/torques.jpg