Glow plug sealing point question

[mkdutchman]

Quick dumb question on this glow plug, where is the sealing point? I'm going to use this in a COV plug and need to know what surfaces are doing what

Does it seal just below the thread, or the whole length of the shaft or just below the shaft where it tapers down to the hot element?

[listerdiesel]

There is a tapered seating either below the thread or closer to the tip. In either case, it is to prevent combustion product getting into the threads.

Much older plugs had washers like injectors, but you won't see that many of that design on modern engines.

Peter