In 2002, BMW released the e65 and e66 seven-series to the American public. It was produced until model year 2009 and had a drastically different body style than the “traditional” BMW chassis. These sleek and stylish Bimmers were popular models, but there are several common problems that owners encounter. One such malfunction is an unknown growling sound coming from the engine.
Many of the e65 and e66 seven-series are coming up on 100k miles, which is the point when many owners start noticing the engine growling. It has been noticed in vehicles with less mileage as well. Drivers first notice a rough idling or misfires, followed by unknown whines, howls and growling. Some owners have said it sounds like a separate engine operating under the hood, or a loud exhaust system of a nearby car. In most cases this happens when the engine is revving at low speeds.
Possible causes of this engine growling and whining could be the air conditioning belt, the alternator or the auxiliary heater. Another cause could be the oil separator valve. Some owners have tested this by running the engine and then removing the dipstick. If the engine changes pitch then it might be the oil separator valve or other associated seals and gaskets.
If your BMW is producing strange growling sounds from the engine, contact a nearby German auto mechanic to figure out the cause, and then perform the appropriate repairs. With so many possible causes, it is best to see a professional.
Search for a local, independent BMW repair shop with BMW mechanics that have dealer-level expertise at a fraction of the expense.