How much higher is the engine temperature? Does the electric fan operate at varying speeds? You may want to have an "activation test" performed on the electric fan to ensure that it is cycling correctly. I worked on an ML500 last week that had visited numerous repair centers to cure a running hot problem. You name it and it was replaced, if not twice then 3 times, all to no avail. An activations test revealed that the electric fan was incapable of operating above 30% speed. Checked the PWM signal from the ME control unit, the fan control signal varied to the degree of activation. (IE: 1.5 V for low speed and 9.5 V for High) Performed a voltage drop test on the power and ground circuits, discovered 9.8 V on the main power lead from the 100A fuse attached to the battery terminal.

If your fan is not capable of operating from as low as 10% to as high 90% with several stages in between then I might suspect it may answer your “running hotter” than normal complaint.


FWIW: Just another .02 in the kitty