Diesel coolant temperature running hot
I replaced the thermostat in my '85 300D turbo because the car was running too cold - typically at 70 degrees C, and it would only climb to 80 degrees when sitting in traffic. I put in an OEM MB thermostat rated for 80 degrees C, and refilled the system with yellow MB coolant, and let the car idle with the reservoir tank cap open to purge any air trapped in the system. The temperature gauge climbed to 90 degrees, and after driving the car for a while, to a steady 95 degrees.