I have a 2000 Jaguar S-type 4.0. It has been overheating

Do yourself a favor and take the car to someone who is experianced with Jag's. you will save more money in the end by doing this. You have air in your cooling system that needs to be blead properly. Their is a lot of components that work in conjunction with the cooling system and they all have to be in working order for the engine not to over heat. Let me ask you this, do you have heat in the car? Is your climit control valve working properly? Is the upper hose have a working bleeder valve on it. is the expension tank in good condition with out any cracks in it. Is your expasion bleeder good? Are you useing the correct coolent. Good luck!

hard to say. you are fixing it yourself with suggestions from mechanics. you need a real shop with real techs to properly diag the car correctly and not guess what the issue is. Roy