I have a 1989 4x4 3500 Crewcab (non dually) with 95,000 miles on it. Truck belonged to the Air Force before I bought it. I could swear I occasionally hear some clatter from the valves as I'm going down the road. I have owned the truck for about a year and it's my first diesel, so I'm learning as much as possible as quickly as possible. Is there a possible ip timing issue here? The truck doesn't smoke when I'm driving, unless I'm pulling a long steep grade, and starts quickly in the morning.