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Some Brabus Roadsters appear to have a manufacturer's wiring fault on the chargecooler whereby the fan spins the wrong way. The effects of this are explained as follows:

The purpose of the chargecooler is to reduce the intake air temperature cooler air is more dense than warm air. This improves the fuel / air mixture and improves performance. This is important on the Brabus Roadsters where there is a greater demand for performance but the larger turbo generates more heat.

The warm intake air passes through an aluminium heat exchanger which rejects the heat to a closed loop water cooling system. The heat is rejected to atmosphere via an underslung radiator which is the lowest engine component of the Brabus Roadsters. This is the part you have to be careful of when driving over speed cusions! Mounted to this radiator is a fan which will continue to pull air through the radiator when the car is stationary.

As you drive, air naturally passes through the radiator fins and lowers the coolant temperature.

On certain cars, the fan has been wired up in reverse which actaully forces air back into the radiator. Therefore, heat is not effectively taken away from the radiator.

By not effectively cooling the intake air temperature you may find that the fan spins the majority of the time. To check if your fan is wired up incorrectly, drive the car until the fan comes on. Now park up and leave the engine (and fan) running. You can get to the fan under the car infront of the nearside (left) rear wheel. Hold a bit of paper up to cover the fan. If the paper is blown back then the fan is wired up correctly. If it gets sucked into the fan, then you need to do some rewiring.

It is clear that the intention of smart-Brabus was indeed to have the fan sucking the air through the radiator (anti-clockwise) to compliment the natural airflow. The 'rotation' sticker on the fan casing would also suggest this was the case.

There are other potential issues with the fan running the wrong way, and that is the fan will now 'push' debris into the radiator, potentially flattening the fins.

To correct the fan rotation, you simply need to reverse the fan wiring. It is possible to do this with the fan in situ. Alternatively, you can remove the fan to clear out any debris that may be trapped in the cooling fins.

The current wire arrangement is Blue->Brown and Black->Yellow.
The correct arrangement is Blue->Yellow and Black->Brown.

The connector is located above the radiator, just under the subframe.

There is a single clip on the connector, just press this in and pull the cables apart.

Use a thin scredriver to just release the tabs on the cable retaining clip.

Again use a thin watchmakers screwdriver (or paperclip) to release the retaining pin on the blade connection itself.

Gently pull on the cables at the same time.

The wires should now be free to be removed.

Swap the wires over, and press back into the plug, they should secure themselves into position.

With the wires clipped into place and the blades are straight in the connector, clip back into place the cable retaining clip.

Now the connectors have been changed just clip back into the main connector in the car.

Reattach the fan (if removed) using this guide.

You will now find that the fan will assist pulling air through the radiator, lowering intake temperature and potentially increasing performance!


Thanks to Jeff Hall on the smartclub for bringing this to our attention.

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