Recently, I have been noticing that the coolant temperature in my 84 380SE seems to creep up if I am sitting in traffic for extended periods. The temperature again gets back to normal when I speed up.

So I am guessing it must be the fan clutch.

Question is - how to go about diagnosing the fan clutch. Secondly, can it be a do-it-yourself repair or do I need a new one ?

Thanks,

Amit