Strange Noise 2k LSI Automatic

My 2K LSI automatic has about 160,000 on it. Runs strong and very dependable. The engine is starting to sound like a diesel. Rattling sound like diesels have when they idle. Changed water pump and timing belt at 120,000 but the sound reminds me of a water pump going bad. I know it's hard to trouble shoot from a distance, but does anyone have any ideas. As soon as it warms up I'll put a stethoscope on it, but the noise really troubles me. I was hoping to put considerably more miles on it. Any input is appreciated.

Has the valve lash been inspected and adjusted at the appropriate service intervals

Has the valve lash been inspected and adjusted at the appropriate service intervals

I haven't checked the valve lash, I'll do it this week end. That's a strong possibility. Thanks SD

It was the water pump. I didn't consider it even though that is what it sounded like. I had it changed 40,000 miles ago. What I didn't consider was the seedy characters at the shop I was dealing with. The corn grows pretty tall around these parts and they must have seen me coming.