Matthias:

This is a common problem. The same thing happened to me and if you'll search the archives you'll find a lot of information on the subject along with discussions about the most likely cause of this problem. The short of it, is crystallization of the material where the radiator hose connects.

I continued to drive my car for a few weeks after the connection failed, but the hose is subject to pop off at any time. To better secure it, I used a piece of wire that I attached to the hose clamp (I think I ran it under the hose clamp and then once around the radiator hose) and then pulled it tight and somehow attached it in front of the radiator. It has been a long time, but this is the general idea.

This is obviously not a permanent fix, but it kept the car on the road until I could order a new radiator and intall it. The only alternative to a new replacement, is to talk to a reputable radiator shop about replacing the top tank of the radiator, assuming that your radiator core is good. You'll find that some shops will do this work, but not all. Those that don't, prefer to avoid the risk of a return due to a leak. To install a new top tank, the radiator has to be removed from the vehicle and taken into the shop. You'd want to get price comparisons between a new radiator and a new tank.

I don't know if you're a DIY person, but installing a radiator is fairly easy. Do a search in the archives and you'll find info on the subject.

I hope this helps.

William