06E350Sport

I noticed that the passenger side air duct has a plastic block off plate mounted, whereas the drivers side is open. Looking at the open driver's side, it appears it is to allow ram air to the front brake rotor. There is even a divider to keep the air separated from the air going into the radiator area. Why would this be blocked off on the passenger side? I pulled the screen off and popped off the retainers that held the block off plate onto the screen. Now the passenger side matches the drivers side. Anyone know why this plate is mounted? I thought it might have been an oversight, but I went to the dealer, and all of the E350's, both Sport models and regular models all have the duct blocked off. I'm thinkin it may be to keep the alternator and belt noise down in front of the car, but I'm just guessing. Anyone know for sure? I know this is an ****, nit-picky thing, but I am curious...

AndrewAZ

I am guessing this is just like the M3 in the US we also have something like this that is blocked off and that is very is to take off your self. The reason being is because of liability. They say it is possible for road debris to enter into the duct and possibly get stuck between the rotor and pad and possibly preventing a brake from working and it is also said it lets more water hit the rotor when it rains and that could possibly decrease braking performance. But like others that do this on the M3 most have come to the consensus that removing it doesn't help cool the brakes anymore than having it on since it doesn't have a duct like on a racing car to direct airflow directly to the rotor, some argue that it could possibly mess up airflow and other say that it could lead to increasing engine cooling. I have just left them in since I don't want any issue with debris/rain from the road entering in. But anyways to sum it up, It wont do anything for cooling effect that will be noticeable or helpful unless you are on a racetrack and it could possibly be a safety issue.

06E350Sport

If that is the case, I wonder why the driver's side duct comes open? Also, I don't believe it would increase/decrease engine cooling since there is a divider separating the air flow from the radiator ram air.

AndrewAZ

No clue but I would think its best to not mess with it since if something does go wrong then they can say ow it was because you took this off.

JimPurdy

The driver's side plate has a hole in it for the outside temperature sensor. The data from the sensor is used not only for the outside temperature readout but also for the A/C system.