What do you have that has a fitting like that?

NPT fittings are tapered and the further you screw them in the tighter they get.

I would think that just three thread is not enough to establish the correct seal pattern.

G

"What do you have that has a fitting like that?"

Heat exchanging block

"NPT fittings are tapered and the further you screw them in the tighter they get."

Correct, but problem is I am getting them so tight the corners of the fittings are beginning to round off.

"I would think that just three thread is not enough to establish the correct seal pattern."

You're very right, and I'll try applying more torque when I attempt to reseal them.

I've found a 15mil thick 1/2" wide teflon tape designed more for fuel sealing purposes. I will try that next along with increasing the amount of torque applied to the NPT fittings. I'm going to have to get a longer 6-point box end wrench.

Pictures please. That will reaaaaaally help.

I will post pictures in another thread. Good news. I grabbed a 6 point impact socket, stuck it on a breaker bar and smoked those fittings down. So far I have observed no leaks. Thanks Gadget for the help and originally the idea.

NO MORE LEAKS