How to repair steam radiator leak?

I have a 2-pipe steam system, which is overall working very well, except for a couple of radiators with pinhole leaks. Last season (my first in this house) i just shut them off, but I would like to attempt to repair them this time around. I assume it's a matter of taking out the radiator, filling it with some substance that goops up the leak, and putting it all back?

First question: am I correct in my assumption?

Second question: what substance? Would car radiator leak plug stuff (never done it or used one) work?

Finally, I've heard of situations where such leak-plugging stufff was pumped throughout the system to plug leaks in walls etc. Anyone know about that? Seems like something like that might wreak hell on T&P valves, etc. (gum everything up). Or?

Thanks for any pointers.

 

The only thing I know of which MIGHT work is an epoxy called J B Weld. Usually the leaking section is just removed & a longer nipple installed on one end of the radiator unless you can find another radiator from which you could salvage parts.
Maybe, KField, who does more steam than I, will see this & jump in here.

 

I just got some JB Weld - thanks for the tip. I will give it a try. Looks like someone already attempted a fix, there's some rather hard black stuff in the general location of the leak... not looking forward to patching patches, though I guess I can always file it all off if it doesn't work, or start again. Thanks! Awesome response and response time for my first post :-).