I like the "stop leak" to seal the water passages. The fine silver powder that you get at any parts store. I've used it for years and it works great! I've been amazed at how well it stops leaks. I keep a tube of it in my glove box for emergency.
Don't use the Bars Leak pellets that look like rabbit ****. They will clog your heater core.
Just pour a little of the silver powder into the radiator (like 1/4 the tube for small issues is needed) then run it for 40 minutes until any leeking/seepage stops and you are good.
