Fairly quick fluctuation probably is a bad temperature sender or bad ground on the cluster. Mine jumps about 10C increments on occasion, its way too fast for that to be the actual temperature.

What's the good temperature for a 240D to be sitting at? Mine is at about 110C-115C in highway driving, around 100C in city driving.

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1983 Mercedes-Benz 240D
Automatic, A/C, Power Sunroof, Power Right Side Mirror
231K Miles FOR SALE MAKE OFFER