New pipe plug (to replace transmission drain plug)
 

Thinking this is to be expected given that the threads on the original 737-0177 plug were likely worn down? Just wondering though and don't want to strip anything.

The original plug went in nearly all the way - perhaps only 2/16" remaining at the end of the plug. This new one - which is slightly longer - is only going in partway but gets tight. Leave well enough alone? I probably had the habit of overtightening the old one - typically would give it a few taps with a hammer after tightening with a ratchet so probably over the years I'm thinking I kept driving it in farther and farther. Overly paranoid about it coming loose I guess...

The pipe plug is a tapered thread, when it gets snug. it is good.
You don't want to hit it with a hammer, or try to tighten it till it is flush,pipe threads don't work that way.
a proper tapered thread should turn about 1 turn by hand then a wrench is needed.
usually being tight enough 1/2 or 3/4 ways in.
But it is a feel thing, if it feels tight than it is tight.
If one over tightens a tapered thread, they is always the chance of breaking the item it is threaded into.
Don't over think this.:beerchug:

Hmmmm...so the implication being that I overthink things?.....LOL Understatement for sure! Thanks for the advice. Will go easy on it.

That's pretty much it. :beerchug:

As George wrote, it's a tapered pipe thread. The taper itself ( along with good threads in the fitting and the plug) is the seal.

The only difference to what George wrote is the plug should turn in about 2 or so turns ( clean male and female threads). But he is dead on on just snugging with a wrench after hand tight.

If cutting new threads with a pipe tap, only go about 2/3 of the length into the hole. I use NPT thread gauges at work but the 2/3 rule gets you close.

Jeff

Thanks Jeff.....great advice.