tapping sound on 2005 GMC Yukon

there is a slight tapping sound comming from under the hood of my yukon. It has a little over 100,000 kilomiters on the odometer and i have been informed has never had any major repairs done to this point.

Asked by for the 2005 GMC Yukon
A qualified technician will need to listen to you engine a try and determine the cause and severity of your noise.
I had a sound similiar to that. Stopped to get gas and put the vehicle in park, it started to roll forward. Transmission would not work in 2Hi placed in Auto 4x4 and transmission works, however still not in 2Hi. Before that I had problems with push button on dash changing from 2Hi, N, and 4Hi.