99 Cadillac Deville overheating

Instead of guessing at a hose and wasting money unnecessarily, head to an auto parts store to borrow a pressure tester. Many stores are borrowing or renting tools now. Fill the radiator with water, then pump the system up to around 15 psi. That will let you search for the leak while everything is cold. Check for loose hose clamps if you see any seepage near the end of a hose.

If the leak is too slow to find this way, you can also add a small bottle of dye in the radiator. After driving long enough to warm the engine and build some pressure, you search with a black light. The dye will show up as a bright yellow stain that you can follow to the source of the leak.