Hi i just bought a 11 f350 powerstroke. CC lariat 4x4 with 70k miles. Whenever i turn off the truck abt 30-45 seconds later a humming starts and continues for abt 1 minute. Sounds like a pump or a release of air? Is this a normal function or should i have it checked out. Ive searched around but found very mixed answers. Thankss in advance!

 

I believe you will find it is the DEF pump purging the lines. It is perfectly normal.

 

Ok thanks for the reply. I was just unsure bc our 2013 f350 powerstroke never does it but i guess its just the difference in years.

 

If you have doubts, check with your dealer. If it is the DEF pump, the sound will be coming from the driver's side in front of the rear wheel well.

 

Nope, the sound is coming from under the hood