Excess pressure can be caused by a defective radiator cap. Have the cap checked or get a radiator test kit, which includes an adapter to check cap relief pressure. Old caps don't fail as much as the cap seal gets old and or cracked and then does not hold correct pressure.
Remember having the correct cap pressure is what allows the high liquid boiling point along with coolant mix.
A TIG weld repair to the tank is a minor repair, not requiring deep grinding and v cut or notching as a structural steel penetration arc repair .
And you have checked the U shaped mounts, upper and lower not folded over the tank flanges sit flat and level. And the radiator is snug, doesn't wobble at all. The mounting plates, upper are holding straight up and down. Not applying any twisting or spreading pressure.
My dually cracked the upper inlet twice, found the long upper hose was bouncing moving to much. Upper should has small moulded are to guide hose but not held down. Placed a u shaped Adel clamp over it, and no more problem.
Good luck.
Remember having the correct cap pressure is what allows the high liquid boiling point along with coolant mix.
A TIG weld repair to the tank is a minor repair, not requiring deep grinding and v cut or notching as a structural steel penetration arc repair .
And you have checked the U shaped mounts, upper and lower not folded over the tank flanges sit flat and level. And the radiator is snug, doesn't wobble at all. The mounting plates, upper are holding straight up and down. Not applying any twisting or spreading pressure.
My dually cracked the upper inlet twice, found the long upper hose was bouncing moving to much. Upper should has small moulded are to guide hose but not held down. Placed a u shaped Adel clamp over it, and no more problem.
Good luck.