Heater Valve question

[Bart]

Hi does anyone know what the thread is for the heater valve? It does not seem to match anything on my bolt gauge?

Thanks!

Bart.

[BDA]

The thread going into the block is 3/8" NPT which is a tapered thread. Pipe threads are meant to seal more than attach (much less clamp) like a bolt. Pipe threads must be augmented by some sealing mechanism such as Teflon tape.

[Bart]

Thanks BDA.

Bart