I drove my 1987 325 one thousand miles this weekend, 500 miles each way. When I reached my destination on the first leg of the trip the car was making a very loud fan or belt-spinning sounding noise. The RPM gauge appreared to be working normally but the car sounded like I was really pushing the RPM’s when in the lower gears, prompting me to get into the higher gears really quickly. The noise was constant, not a clatter at all. A friend thought it might be the hydraulic part of the clutch- the clutch master cylinder was replaced 5 years ago. The gears don’t stick at all or feel any different. I fear it may be the beginnings of my transmission going bad. Any ideas?