Lifter noise

In July 2005 I developed a lifter noise in my 2004 XG350i. After several visits the dealership replaced the motor (short block). Since that time I have experienced the loud lifter noise about every 3- 6 months. This is not a light tapping sound it's very loud and goes away after several minutes of run time. It's like the oil drains from the motor and doesn't recover fast enough or the oil pump fails to work at start up.  I have taken the car back to the dealership but they find nothing wrong nor can they reproduce the problem. Has anyone experienced this?
 
 

Could be a blocked oil way.  Might be worth flushing the oil system, fit new filter and replace the oil if you haven't already tried this.
 
Chris.

Do these car have HLA?

when replacing a short block it doesn't come with new oil pump and the dumbass who did it probably didn't replace the oil pump that's why you still have that lifter noise