2003 Jaguar S-Type coolant

that is not a very clear pic because of hoses in the way. In our manual we don 't list a 2.0 unless this is a diesel. all we list is 2.5 and 3.0 and it either connects to another hose or it's part of the water pump. pic is what we show in our books.....

Oops I meant 4.2L v8. And I believe there's a waterpump hose right behind this mysterious part?

ya know it always helps when you give the correct info. the pic i sent was for a 2.5L ok I think this beast of a car is also supercharged as I went and looked at auto parts and this is what I could find. we call them freeze plugs here but there is another technical term for them. Anyhow see if you can find one at an auto parts the same size and make sure water pump isn't damaged. where it goes in. then clean out hole and get some blue Loctite put on the edge of plug all around then drive it in, you should feel resistance going in. you can use a socket. if it just slides in get another water pump. because even Loctite won't help. Wait a coupe of hours before refilling system to give the Loctite time to set up.