I recently bought a 1991 F150, as a snow plow truck. The original radiator had issues, so I installed a new one. After a test drive, all is good. When I got home, the plastic end exploded off the new radiator, under the filler neck. Sooo, do I assume it's a defective radiator, or can a seperate issue cause this explosion? Please help!?!?

 

Did you also use a new radiator cap? If the cap is defective it can overpressure.

 

A leaking head gasket could cause that, leaking compression into the cooling system building up too much pressure. Hope it's not that. Very well could have been a bad radiator.