New harmonic balancer + knocking sound
 

I've got a 2006 IX MR with just under 120k on the clock. Couple weeks ago the engine started making a fairly pronounced knocking sound, turned out that it was the timing belt on it's way out. I had a shop replace it, and about two weeks later decided to replace the stock crank pulley with a harmonic balancer. The stock unit's bolt holes had been bored out a bit from uneven wear.

After the timing belt replacement, all knocking sounds were eliminated. I drove the car for about a week before then having a harmonic balancer (Fluiddampr) installed. Now, after maybe 5-10 minutes of driving (normal commute, no thrashing) I hear a knocking/tapping sound coming from the timing cover area at idle. It's not nearly as loud as it was when before the timing belt was replaced. The shop checked everything again, nothing is loose and there is no belt damage. Is this a normal symptom of a harmonic balancer?

Any thoughts/tips would be much appreciated.

Chowdered holes mean loose damper - maybe the cause of the original sound. Its difficult to say what you are hearing now, motors make more noises as they age. A damper shouldn't make any noise.

Good idea replacing the damper. The rubber gets hard or can break letting the outer rim come off. I replaced mine at the second timing belt interval.

did you change the timing belt tensioner?

Yes, tensioner was replaced as well.