I was still pretty skeptical about the water pump being the problem. After checking many old posts I thought that the radiator made the most sense.
I just finished replacing (supplied by Phil) and it worked like a charm. Now the temp stays at the 80° on the gauge. Thanks to all who helped me on this frustrating problem.

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1986 300sdl
1984 300sd
1988 300se
1973 vw thing