There is nothing wrong with any OM603 that gets to 100 degrees C on a hot day with the AC running. Completely normal.

Its those white and especially red marks 115 - 120C that one should concern themselves with.

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1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)