Hello -
I have an annoying engine knock on my 99 2.8 A4 (145k mi) that's puzzled the mechanics that haved attempted to diagnose it. Here are the symptoms:
-When the engine gets warm, there is a knock/rattle noise coming from the lower part of the engine on the passenger side.
-The hotter the engine gets, the worse the knock gets.
-The knock can only be heard when the car is idling. When the engine is revved over 1000 or so, the engine sounds perfectly smooth
-The car's idle is somewhat rough
-The knock persists when high grade gas is used (only a handful of times have I used less than premium since I've owned the vehicle)
What I've been told:
-Timing belt. *I am somewhat skeptical of this, as I had the timing belt replaced at 90k (55k miles ago).
-Oil pump chain stretched and hitting side of engine. *Not sure about this.
Has anyone experienced anything similar or have any thoughts? Any input would be VERY much appreciated.
Thanks!
--Ted