My 06 2.5si has developed a strange noise when acceleration hard.
I can only describe it as a cross between a rattle / wind noise above about 4000 revs in 2nd and 3rd. It might do it in 4th and 5th, but I can't hear it over the actual wind and exhaust noise at that speed!
It appears to come from the left hand side of the engine bay when sat in the car. I can't hear it when I have the bonnet open and rev the engine, so cannot localise it any more than that. I don't think it's exhaust related, as it's the wrong side of the engine and both down pipe flanges were repaired late last year.
It does not sound like pinking or knocking and engine power does not feel noticeably down. Could it be a Vanos issue all the same?
All suggestions gratefully received
