I have a 2010 subaru forester, non-turbo engine, automatic transmission. It has about 90,000 miles on it. In the last year I've noticed a growling sound coming from the front end of the car when idling after startup (warm or cold engine) and while coming off acceleration (while in park). I haven't noticed these noises while driving, but I may just not be able to hear them. I took the car to a subaru dealership and had them take a look at it back in June. I figured it was belts. They checked everything and told me I was fine. They said it was probably the heat shield. Another component to this is around the same time I began noticing the noise, I also noticed my MPG dropped. About 3 MPG (which I find significant). I have changed the spark plugs and the air filter to try and fix the MPG issue, but it only slightly came back up (maybe 1 MPG).

This is a little concerning to me as it's our family car for my wife and child. I'm hoping it's not the timing belt.

Does anyone have any suggestions on what it could be or what to look for?

heat shields can definitely react the way you describe. It's a frequent complaint - but, kinda surprised the dealership didn't jump at a chance to charge you for their repair so - at this point, I think another opinion might be helpful.

 

bad knock sensor might cause the engine to 'rattle'  AND affect mileage, though I'd expect it to be worse on acceleration, not coming off.

 

ask in a new thread for a recommendation and maybe someone near you in 'west by god' will know of a good shop.

Edited November 11, 201510 yr by 1 Lucky Texan

At 90,000 it is just about time to do timing belts.  The growl might be an idler bearing on its way out.