I have a 1986 190e 2.3-16 valve that suffered overheating as well. After the radiatior was replaced due to it blowing a leak, it overheated again but I caught it before anything happened. I suspected the fan switch that controls the fan clutch. My car has two fan systems. One is the fan clutch itself. The second is the auxiliary fan the comes on when the a/c is used. My car now hovers around 87-100' C. That is normal operating temp. A darn cheap switch controls the fan clutch. It cannot be checked so I just replaced it. Try it.