What size threads are the engine block coolant drain plugs on the 2000 7.3? I'm having to demolish them to get them out...

 

 

They are 1/4" square holes for those plugs. For a 3/8" breaker bar you will need an 3/8" to 1/4" adapter.

I have one that is rounded and the other one doesn't want to budge with as much force as I feel comfortable putting to it.

I'm curious if someone has the size too so I can replace mine next time I flush the coolant.

I remember reading another thread on this but I don't remember if they figured it out or where the thread is.

 

The plug looks like it's 1/2" diameter, so it's probably 1/4 NPT. Mine won't budge at all, and I may have to drill and tap it to 3/8 NPT.

 

 

Already tried PB Blaster and let it sit overnight. Still won't come out.

 

 

I drilled and tapped it to 3/8 NPT and put in some brass hex-head plugs. There was just barely room enough for the bigger plug on the left side. Flushed the cooling system, used Form-a-Gasket #2 on the plug threads, and I have no leaks.