I have had a tapping sound,seems to be coming from the front of the engine for a couple of months now ,it sounds the same if the motor is hot or cold at idle or revving .I had it back to the dealer last week they checked the turbo injecters lift pump and high pressure pump also set the valves and the tapping is still there it just sounds like valve lash to me but as i said they were just done .Does any-one have any ideas as to what is making this tapping i am starting to loose my mind over this.The truck works great starts good runs good and pulls hard the dealer is all out of ideas also ?????