So here’s where I’m at... I’ve removed the radiator, cleaned the area, and then I used my soldering iron to melt/close the cracks running away from the hole. I added an epoxy used for nylon/plastic. I hope the photos work. Also, I figured I’d go ahead and replace all the hoses (coolant, fuel, etc.), thermostat, and the radiator’s rubber bushings while I’ve got the thing apart. I plan to also apply some epoxy internally to fill any gaps there too. Anymore suggestions?!!?
Now the true test. Before putting it back on you need to do a pressure test.
Go to somewhere like TSC along with your rad hoses. Buy some cheap plastic fittings. One to plug one of the rad hoses and a second to reduce the size to the point that a schader valve will screw into. A schrader valve is like the one on a bicycle tube to add the air to keep in inflated. TSC will have schrader valves intended to be used on well pump tanks to add air to either the old style tank with a floating diaphragm or the new ones with an internal bladder.
You also should get a bicycle pump and a cheap pressure gauge to use with the schraeder valve.
DO NOT USE AN AIR COMPRESSOR!!!! NOT EVEN THE ONES YOU PLUG INTO YOUR CAR.
Fill the rad almost completely full with water.
Put the rad cap back on. Slowly add air through the schraeder valve checking often with the pressure gauge. Since the rad is almost completely full of water which is in-compressible, the pressure will go up much faster than when filling a flat bicycle tire.
If you go too high the rad cap will start releasing pressure. You want to find the pressure just below when the rad cap releases and let the rad sit for an hour. At the end of the hour check the pressure and look for leaks.
Pressure still good and no visible leaks you are good to re-install.
Don't continue to check the pressure during the test and the act of testing itself will drop the pressure.
DO NOT USE AN AIR COMPRESSOR!!!! If you do, even with great care and a regulator it is very very easy to rupture the rad.
Dave