2004 Mercedes-Benz SLK230 Radiator Fan Motor Replacement Cost

The engine in a vehicle gets hot when it is running because of friction caused by its internal moving parts. While the engine oil helps to reduce the friction, the cooling system circulates coolant (also known as antifreeze) through the engine to manage the temperature. Once the coolant leaves the engine, it cycles through the radiator, where wafer-like ribbons, or “fins,” of aluminum absorb the heat and allow it to dissipate in the air that passes through the radiator. The engine’s cooling fan helps to draw a higher volume of air through the radiator, especially when the car is at a standstill, so that the coolant temperature decreases. For the most part, electric cooling fans are controlled by the same computer that controls the engine. However, in some engines, the fans are turned on and off by a temperature-sensitive switch mounted in either the radiator or elsewhere in the cooling system.

If the fan motor does not work, there will not be enough air movement through the radiator to dissipate the heat in the coolant. The symptom usually associated with a faulty fan motor is an overheated engine. Signs include a temperature warning gauge on the dashboard, steam coming from the engine compartment or from under the front of the car, or sluggish engine performance. A check engine light might come on if a cooling fan motor is inoperative. A blown fuse on the fan circuit could indicate a problem with the fan motor as well.

If the cooling fan motor does not work, airflow through the radiator will decrease, the temperature of the engine will increase to unacceptable levels, and the engine will overheat. Under most circumstances, there is not enough airflow through the radiator without the assistance of the cooling fan. A vehicle should not be driven if the fan motor is not working correctly and the engine is overheating. Serious damage to the engine can occur if it is allowed to overheat for an extended period of time. If the fan motor fails during driving, it may be possible to drive a short distance as air naturally passing through the radiator will help to cool the engine, but traffic stops will decrease this ability. Get this fixed by a RepairPal Certified Shop

There is no replacement schedule associated with an engine cooling fan motor. Many fan motors will last the lifetime of the vehicle. Fluid leaks in the engine compartment may shorten the life of the fan motor and should be fixed as soon as possible.

To check for a malfunctioning cooling fan motor, a technician will run the engine while the vehicle is in park and allow the temperature to build up to operating temperature before turning on the air conditioning. This should cause the cooling fan (or fans) to turn on. If the fan does not turn on, the technician will check for a blown fuse and a faulty fan motor relay (the most common cause of a failed fan motor).

If the cooling fan motor is found to be defective, a technician will allow the vehicle to cool before attempting replacement. Depending on the vehicle, a number of components - shields, covers, grille, upper radiator support member - may need to be removed in or around the engine compartment to gain access to the cooling fan assembly. On some models, the radiator may need to be drained and removed in order to change the fan motor. The technician will unplug the fan(s) from the wiring harness, remove the relevant accessories, disconnect any brackets holding the fan assembly in place, and remove the assembly. The unit will require disassembly so that the old fan motor can be removed and the new motor be inserted into the assembly before it is installed in the vehicle. If the radiator had to be removed, the coolant will need to be replaced and air bled from the cooling system.

RepairPal recommends that a thorough diagnosis be performed prior to replacing the engine cooling fan motor. The most common cause of an inoperative fan motor is a faulty fan motor relay; a fan motor is often misdiagnosed and replaced when the relay was the problem.

A vehicle may incorporate two cooling fans - one for the radiator and one for the air conditioning system. It is important to be know which motor is faulty. It is also important to check the fan motor relay. Most importantly, the engine must be allowed to cool prior to any work being performed on the cooling system to prevent serious injury.

On many vehicles, replacement of a cooling fan motor is an intermediate DIY repair requiring some experience with removal of components in the engine compartment, including (if necessary) the radiator and coolant hoses. It is also helpful to have some knowledge of diagnosing electrical issues since many fan motor problems are related to the relay rather than the motor itself. Also, keep in mind that the engine needs to cool before work is performed.