Could it simply be air going through some part of the car and creating the hum?

 

Yes and no. After over 40 years in the auto repair \business, the hum is not any sound I have heard from an air leak. But, as you suggested, I thought. well, maybe it is. So I tapped off all the body channels windows hood channels. I even closed off the front air intake grill and drove the car. I even taped over all the undercarriage covers. I taped over the wiper blades because they have some openings that might cause a noise. I did that on a cold engine and only for a brief time.

Also, the hum starts at 12 MPH. That is very low speed for wind noise. The loudness is generally the same at 12 mph or 90 mph. Although on very smooth roads it seems a bit quieter and over rougher roads it gets a little louder.

Lastly. this hum changes pitch when going over bumps. I cant see wind noise reacting to bumps in the road.

Your idea of keeping it simple is spot on. In the end, most automotive repair issues are simple once they are diagnosed.

 

I did have a similar issue once with another car and it turned out to be the brake pad spring was rubbing on the wheel (clearance was tight).

 

Indeed.... But the hum does not go away with any brake use. The dealer " said" they inspected all the pad calipers etc. I did not trust them so prior to leaving the car with the dealer, I put white out on some of the brake components to see if they would check them. They did .. all white out marks were disturbed. This local Jaguar dealer is a total disorganize shop without real talent in the repair bays.

 

On mine it was the brake spring (the metal bar that is under tension). This doesn't move when the brakes are applied. You can see it through the wheel vents. Although with higher speed I would think it might change pitch.

 

JagGate. let me add, I did jack up each wheel and spin them with an old style on the car wheel balancer. I did it at slow speeds and high speeds. No unusual noises.
Yah, I still have some of that junk around along with my handy dwell meter.

 

Jag, Gate... I will double check that as you are right...maybe...