The Sorento 3.5 5 cyl has a timing belt. According to the Gates Timing belt guide, the Sorento is due for a timing belt change a 60k miles. When I was looking at a 2005 Sedona (same engine), the timing belt change interval was 60k miles also. Here is a link to the Gates guide:
http://www.gates.com/downloads/download_common.cfm?file=428-1466_web.pdf&folder=brochure
This is an interference engine, so if the belt breaks, there is a high probability engine damage will occur. Double check your Owner’s Manual to verify the change interval. If this is the original timing belt, you are on borrowed time.
Ed B.