As I am sure you can appreciate it is difficult to diagnose a noise one cannnot hear. I will provide an honest goodo faithanswer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.
the most common cause for this would be an air or exhaust leak, or a failure of the crankcase ventilation system
also, belt drive components can also cause a growling type noise
the next steps will be to run the vehicle briefly without the belts, and if the noise is still present, then have it traced with a mechanic's stethoscope
wheel bearings are also common to growl, but that would be from one wheel, not the engine
Sorry if you were hoping for a different answer, please don't shoot the messenger - I can only give the honest answer, which I have. Please remember that a low rating PUNISHES me for my honest and prompt response, and I receive nothing for my time and answer until a positive rating is clicked.Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.
Thanks! It was only serviced less than 1k miles ago and no mention of this problem on a full service..should I go back to them?