Steam radiator vent

[LiveFreeOrDie]

Hello,

I have a steam radiator that is always cold, and I'm guessing it's the air valves. Problem is I can't get the existing top plug air vent out to clean it, and I can't get the small middle slot screw out to install a new angle vent. Any thoughts on how to move forward before I start drilling and extracting things?

Sorry for the very small picture.

Thanks for any help!

John

[HayZee518]

chances are the steel pipe plug is "welded, rusted" in place. a 5/16" drill is the size for a one eighth inch pipe tap. I would center punch the plug and drill in progressively larger sizes up to the 5/16" bit. then run your tap in slowly. if it taps steel you'll have a spiral chip come out. if its in cast iron, the chips are just cast iron chips.