What is all the causes for a engine to over heat?

Suspect a leaking cylinder head gasket. You can verify that by adding a small bottle of dark purple dye, then check at the tail pipe with a black light. If the head gasket is leaking the dye will show up as a bright yellow stain.

Yes, when the engine is still cold. You can buy the dye at auto parts stores. They will ask you what you're going to be adding it to and they'll give you the right product.