load tap under hood

[four_barrel]

Hello,


The 1985 Mercedes-Benz, 300D, 617.952, 123. Mileage 86,000.

Shortly after the owner purchased this car he said the sound started, like a lifter taping vary loud. I removed the valve cover and checked the rockers, cam, valves and springs (didn't see any broke), adjusted valves if necessary. I am planning compression test tomorrow. What else is there to make this noise, wrist pin, connecting rod bearing (pistion slapping head) . I have tried to pin point the sound vary difficult. Any other ideas are well come.

Dan