I have a 1986 560 sl. I was driving it one day when a spray came out from under the hood. I stopped the car and found the upper radiator hose had come off top of rt side of radiator. The plastic neck had broken off and was inside the detached hose. There was enough of the neck remaining on the radiator so I reattached the hose. Before this happened temps were normal(80). The reservoir was to its full mark. It did not appear very much coolant came out. When I continued driving the temp imediattely started to climb and got no more than a half of a mile before I had to stop(120 degrees)and shut off engine. I checked under hood and the hose was on and coolant still showed in reservoir to its full mark. I let cool down to 80 and drove again but could only go a short way(120 degrees) before had to stop and go through whole process of cooling down. I had to do this for about 6 miles until I got home. I let cool down over night. As soon as I opened reservoir it drained down and I put about 8 qts. of water in. Now it works fine. So, what happened. Specifically I am wondering why the neck of the radiator broke? Why didn't the coolant in the resevoir drain into the radiator? the coolant that sprayed out appeared to be only about a quart or two. Did I hurt anything by driving it in short distances, until it got to about 120 degrees and then shutting off for the 6 miles home. The hose appears to be secure on the short neck but would you put new radiator in to have full neck for hose to be attached to? Thanks. Rob Thomas