[zzmac]

Yesterday I tried the shopvac and I also tried our central vac with a smaller hose attached to it so it could get around the corner of the lower outlet and into the rad. Didn't work.

The bolt is made of brass and when I was drilling a small hole in it, it grabbed the bolt and spun it right through the threads of the opening (the threads are fine, just needs a new bolt).

What harm , if any, could happen if I just left the bolt in the rad?