Diagnosis and Testing: Diesel: Noise

WARNING: This page is about a different car, the 2011 RAM Pickup and 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

It is normal for fan noise to be louder (roaring) when:

Fan duty cycle high. This may occur when ambient (outside air temperature) is very high.
Engine loads and temperatures are high such as when towing a trailer.
Operating conditions where transmission temperatures may be high
Cool silicone fluid within the fan drive unit is being redistributed back to its normal disengaged (warm) position. This can occur during the first 15 seconds to one minute after engine start-up on a cold engine.