Today was the first day in several weeks that I had my 2010 XF SC out, since the snow hit PA. This evening when I came back from a little fun driving, I notice a humming noise coming from the rear end when I shut the car off. It lasted for a minute, followed by what sounded like rubber being compressed and a little air excape. Never notice this before because I generally park in the garage head first, today I backed her in to unload some goodies from the trunk. My wife said she noticed it before when I shut the car off after a good hard drive. I only look out for out of the ordinary noises while driving. Sorry if this has been mention before.

 

Mine does too. It is supposed to be normal. It has something to do with the fuel tank ventilation. It will also make odd plunking sounds on occasion. Weird but normal, according to my dealer.

 

Thanks, I thought that it might be normal. I was thinking maybe it was the suspension or something like that? I looked under her and notice a little plastic tube coming from behind the rear wheels, Maybe some sort of pressure release or something?

 

That's more likely the sunroof drains. There's also a battery vent tube in there somewhere.

If the noise you are hearing is the same one as in mine then it is internal to the gas tank ventilation which is sealed from the atmosphere except through the charcoal evaporative emissions cannister.

 

I was able to do a little research today after work.. Its neat how the tank and fuel systems works. The Tank ventilation system does make noise after the car is shut down. I guess it was one of those things I never really notice. Just one more item, I got a chance to learn about.

 

I had this issue come up for me yesterday...It was making a buzzing sound from the rear of the car..just got back after a bit of a long run (about an hour) and it buzzed for around a minute..and clicked off..I figured it was something do do with the fuel tank ventilation process, but wasn't sure until I found this post on google...thanks for the info..