I believe that I have found the problem with my cooling system, it is not definite but I want to take a gander at this annoying problem. So, I want some insight on replacing the Engine Coolant Temp Sender or whatever that part is called which lets you know the coolant temp in a Mercedes Benz 300 D Turbo Diesel. I want to know the difficulty of putting a new one is, what tools to use etc. The reason I believe this is the problem and is faulty is it seems to jump around like it has a mind of its own. noticed my temp guage went up around two millimeters below the white line under 120 degrees celsius after the car had ran somewhat cool I guess, and then after religiously looking at the guage it flickers up to that mark. I then pulled by the video store and shut the car off with the guage remaining at that mark and after shutting it off and turning it back on it was giving a reading of around 100 or less I dont quite remember the exact temp. After that I drove it back home and it was around the mark that it was first at so haha. It seems like the faulty componet. So guys help me out on how to replace this part.