Audi Repair Questions? Ask a Mechanic for Answers ASAP
These engines have a mechanical 'high pressure' fuel pump in that area that is fed by the electric fuel pump in the fuel tank. The high pressure pump works off of a lobe on the camshaft. The is a lifter (I think they call it a tappet) between the action rod on the high pressure pump and the lobe on the cam. What usually happens is the lifter wears out and the noise comes from the excessive play between the cam lobe and the lifter. If left un-fixed the cam may become damaged.
Let me know if this explanation suits your needs, if not, let me know and I will get you the information you need.
Okay, I didn't realize you had already been into it. Which solenoids are you are you feeling the noise in? Any codes setting?
Okay, so we are talking about the cam adjustment (cam shift) actuators for cylinder #1, correct?
Since the noise stayed there then I am thinking the problem is in the lifters. The fact that the screen was missing makes me think it was removed to improve oil supply from sludging. Since you had it apart and didn't notice any visible damage then I would think this also points to the lifters. If the noise was not there before they they could have lost oil and just collapsed. I will keep thinking about it, let me know what you find.
Just following up on what you found.
Great! Glad we got it fixed.
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Just following up. I see that you have not given me positive feedback for my responses. Is there something more that you require? Sounds like that was the fix so if there is nothing else, please rate me with positive feedback so I will receive pay for my time.