Hi, Sorry I have to say that if you need to ask how to replace a radiator, you will need help from someone who knows how. It's not a trivial job. Having said that, the problem may be relatively simple. It's not uncommon for the radiator thermostat to cause overheating symptoms and or produce symptoms of leaking. Plus it's a lot easier to replace than the radiator. What you could do is take the thermostat out just for testing reasons. A lot of people do that and then never put it back. But your should have a thermostat because your car will take a lot longer to heat up to normal temperature without it and also likely cost more in fuel to run. Okay, to change the thermostat: Make sure the car engine is cool to cold. Don't try to remove it after driving. It can be dangerous. There is a danger of getting burnt by boiling hot water if you ignore this advice. Once you are sure the car is cold, take the radiator cap off. Check the coolant levels while you are looking. Partially drain coolant. Remove the hose to the manifold, remove the thermostat. Also check out a few sites that show information on your brand and model of car. EG: http://www.2carpros.com/questions/oldsmobile-cutlass-1989-oldsmobile-cutlass-how-to-replace-thermostat - This site shows details on how to do it. Rgds, Dave.