Have you visited the Dealer?. When I thought mine sounded like it had Nuts & Bolts going around, Paid a visit.Chief Tec walked out, Said "Vanos" and walked back-Goodby!!.Had a feeling this might happen , so made sure it had a warranty.BMW NOW proceed with a 3-4 stage check, instead of renew straight away, then renew stage x stage.took 8 days this way.Presume this proceedure was due to MANY expensive claims for vanos.Have NEVER got a answer to "why were the owners used as development engineers" instead of the department who should have made sure it was correct for production.??.All work was covered, at times still seems to rattle, but having compared with other Z,s all seem the same.Could be worse!!!!, some have had two replaced
SAFETYFAST