I have sealed holes around cables and pipes with steel wool . . . it tends to discourage gnawing; however, if it's in a moist location, it will rust like crazy. I now use fiberglas insulation for the same purpose.
Radiators do not have exhaust.
Drill a hole in the rock until you get to the oil. Insert a steel pipe into the hole, and pump the oil up from the bottom of the hole.
Copper you can. Treat it as you would any other connection, clean the area, surface and hole, get the moisture out and solder a patch over it. Small hole, you can just use solder or you can cut a small piece of pipe in half, clean and flux it and put it over the hole. Steel pipe, you can braze over the hole, same basic process as soldering, clean and fill with braze.
China is a large country to export steel pipe, if you want to buy steel pipe, you can import from China.
it is inside the steel pipe in front of the throttle body. Just follow the upper radiator hose from the radiator. It will lead you to the thermostat housing.
what kind of "pipe"? solid metal pipe, or flexible rubber "pipe"? number one cause is from aged rubber that dries out and cracks. loose hose clamps, wore a hole through it, cracked thermostat housing, etc.
Mexico exports steel pipe and tubes
Australia makes steel pipe and tubes
Brazil makes steel pipe and tubes
California makes steel pipe and tubes
China exports steel pipe and tubes
China makes steel pipe and tubes