While driving the other day I experienced what seems like a knocking or thumping sound on the ‘97 850. On startup this morning it was still there. It doesn’t seem like it’s coming from the head or bottom end, not metallic sounding and more in the area of the accessory belt (timing chain was replaced 10k ago). The sound/feeling changes with RPM. I’m thinking it could be a bad pulley or something as the AC went out a few weeks ago but unsure and hope one of you may have an idea.
Thanks!
Peter