Chrysler Repair: 2006 Town & Country Limited 3.8L (52,000 miles), vacuum leak detection, noise issue

Question
Hello Kevin,
At normal operating temperature, the Natural Leak Detection Pump in my vehicle starts making a very noticeable buzzing sound that varies in loudness according to the engine rpm's. Also, after the vehicle is shut off the sound can still be heard for a couple of seconds. I replaced the pump with a new Mopar unit and the sound disappeared for about a day but then returned. There are no codes and the vehicle runs fine but this sound is very annoying to say the least. Is what I have described a common sound for this pump to make? If not, what could be causing it to sound that way since I have already replaced the pump once.
Thanks for your time and help.

Answer
Hi Rennie,
I looked into the '06 manual and found that there is a natural vacuum leak detection assembly as well as a leak detection pump. There is no discussion about the noise issue and because I don't work at a shop I can't tell you about the common sound the pump would be expected to make. Unfortunately I can't help, and neither can Kevin as he referred your question to the 'pool' where I found it. Good luck on getting some help on this.
Roland