Oil pump problem, or oil distribution bridge to the cam shaft bucket tappets?

[simonshearer]

1997 SL500

For the most part, when cold this engine exhibits no lifter "ticking."

At operating temperature and at full load, the engine ticks quite loudly, but not always. Today for instance I probably drove it 30 miles and only at the very end of the trip did I hear that ticking sound.

I read a TSB about tappet noise that suggested to check the oil bridge covers, especially on the exhaust side; I did, they all looked fine to me. They also look like they're held in place by the camshaft bearing caps.

Has anyone experienced the same noise, and has a suggestion for next steps?

[simonshearer]

One of the camshaft oil feed pipes was bad. See the picture of side by side good and bad. Had to remove two camshaft bearing caps to replace it.