my daughter has a 1989 mini that develops a rattle that sounds like something stuck in a bike spoke, when it goes over 40mph. a couple of garages have had a look and aren't sure, so it looks like changing parts untill it stops. has anyone any ideas what it could be. its not wheel bearings and happens more under load. she lives over a 100 miles away but i should be seeing her later.
Just a thought. I had a similar noise on a car with a similar engine and it turned out to be a frayed/cracked fan belt. A lot less expensive than an engine bearing and easily checked visually.
I had a similar noise on a Mercedes many years ago. It turned out something (I can't rmember what) had come loose and was slightly catching the plastic cooling fan.