whats this plug for?(not electrical)

[Cobra_Dusten]

Bottom of my master cylinder. Square brass plugs, its dripping fluid and causing me to have a hyraulic leak...

do you guys think its something i can pull and put a new plug in, or is it going to require a new master cylinder.
I already tried tightening it.

here is a picture. This is on an 89 vert, but because i have sn95 brakes i assume its an sn95 master cylinder
View attachment 249949

 

[Cobra_Dusten]

imma pull the plug later this week and see if its got an o-ring on it

 

[1991vert]

my bet is no. im willing to bet it's a regular NPT plug, which are flat on the bottom and that port is dished inwards so it would need the correct plug to seal. looks like a 3-to-2 conversion gone wrong

 

[Cobra_Dusten]

my bet is no. im willing to bet it's a regular NPT plug, which are flat on the bottom and that port is dished inwards so it would need the correct plug to seal. looks like a 3-to-2 conversion gone wrong

any ideas on what to do?