Lee, have you made sure you have the updated fan and fan clutch? In my 1988 300ce I replaced the original versions and the temp needle no longer runs up to 110 degrees within minutes; now it stays below 100 and I have stopped worrying about non-highway driving. What a relief.

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87 300e (white/black; amg body kit)
88 300ce (red/cream; amg body kit)
93 300ce cabrio (white/blue/blue top)
93 300ce cabrio (black/grey/black top)
98 ml 320 (totaled @ 137,000 miles)
99 clk320 (black/grey/black top)