mac, stress is the big factor - like if a previous owner had front collision (many pay cash,showing NOTHING on Carfax
). Sometimes when working on engine compartment WE put heavy things "on top" that transfer pressure onto those damn plastic radiators. Oughta just get a replacement Lifetime Warranty one , since your NOT sure why it broke - You'll want to go back and get a FREE one in a year and 1/2 right?
Tip - Get NEW radiator CAP too,in case too much pressure not relieved properly is a problem.
You have one of those "mobile mechanics" do the labor
,put like an Autozone (one in myJ30 great for 6+ years now).