My 2002 CVT Cooper is new to me, but has over 100k miles. I recently put a new CVT in it as the old one was bad. I've searched for clues on this problem and am looking for some additional insight as to what it may be.

When I'm cruising between 50-70 mph on the highway, I can hear a very faint pulsing sound coming from the front of the vehicle with a frequency of about 1-2 per second. It sounds like the overlapping frequencies of individual tire noise. The frequency seems to increase proportionally to speed, but I'm not too sure since the engine noise gets louder as I accelerate, but it is there again if i settle into a cruising speed


I have a variety of theories..

1. Tire noise as mentioned above. I have considered a front to back tire rotation to see if it changes, but haven't taken the time yet.

2. Engine throttle position modulating at a constant speed - assuming that there is some mechanism that keeps it at a set speed although the throttle is very slightly increasing and decreasing to maintain a constant speed.

3. Wheel bearing(s) - nothing would suggest they are worn when it was on a lift and applying pressure to see if the wheel moves in any direction other than the proper rotational axis.

4. Right side axle carrier bearing - didn't heavily evaluate this when it was off, but it felt tight.

5. CV joint noise - again, they felt tight and I would expect noise at low speeds.

6. The CVT - I don't even want to go there:eek:

Otherwise, it drives fine, steering, acceleration, braking, tracking.

Is this perhaps just my oversensitivity to the car due to the amount of work and money to swap the CVT. I suspect it will give me some more clues as I continue to drive it since I've only had it for about 300 miles so far.

Any ideas, theories?

I rotated the tires and can still hear the sound. It's a very slight sound. Anyone have any ideas?