Radiator replacement? Or teflon on petcock threads?

[abscate]

JB world or any epoxy will hold well there. I patched a hole on a radiator with JB on metal and it held fine.

Here, you are just plugging threads of the petcock in the hole..no problem, great application

[98v70dad]

Marco,
I haven't looked closely as to why mine is leaking and at first I thought of replacing it with a new one although I didn't see anything wrong with the current one. I too, get variations in the actual leak. At times it doesn't drip at all, other times will make a 1-2" size puddle.

98v70dad,
My issue with JB Weld is that you have two different materials and when one heats up it expands and if both materials are not chemically the same, the rate of expansion and contraction is not the same thus making JB Weld let go. Now RTV (grey for water pumps and thermostats) might be a better candidate and i will try that before I go the bolt way. I'm still running on distilled water (had to put some silicone hoses) so for me it won't be an issue.

JBweld makes a pretty good repair for many things on a car. The only thing I tried that didn't work was a repair to the high pressure steel line on my steering pump. I knew when I did it that it wouldn't last before it started leaking again and it didn't. However, it lasted for 2 days and I was just trying to get it to the weekend. Its best to design your repair to put epoxy or JB weld (an epoxy putty with metal fillers) in shear or compression. Tension or pulling on JBweld usually is a bad choice unless the loads are low.

For your drain you would just be putting it on threads which has the JBweld trapped between two pieces of plastic. The JB has no real choice but to go along for the temperature change ride. IF you decide to go that route, you need to get the surfaces clean and dry. Rubbing alcohol is a good way to clean the surface and it also aids in drying. What I meant by being committed is that you're essentially glueing two parts together and they will not come apart afterwards. The RTV sealant, if you can find something suitable, will fill the voids and you at least have a chance of getting it apart if you need to do that.