2002 E39 525i 5-speed with the M sports package (but it's not an M car - and this info used to be part of my signature with the old site...anyway...) - @140,000 miles on 'er. Over the summer I replaced the tires with a set of new Michelins (Primacy mxm4's). They are speed-rated for this car and fit/ride like they were meant to be together! Lately I've begun to hear a strange noise, sounding like a lawn mower, at crusing speed (@60-80 MPH). I don't notice any power or MPG loss, don't notice any leaks or engine issues (no smoke, sputtering, hesitation, etc.), the car seems to be running normally (save for a slight increase in road noise but I thought that would be normal after tires are a month old). That is, except for this "lawn mower" sounding hum. I do notice that when I take my foot off the gas but maintain my speed, I do hear the sound...so again, I don't believe it's engine related but...I don't have that kind of acumen to be able to know for sure. Questions abound...could the tire(s) be rubbing on something, could there be something loose, is it an issue related to alignment or bearings or some wheel-related issue, or do I have a problem with the engine after all? Any and all ideas/thoughts/replies will be most appreciated...thanks!
Lots of possibilities Frank - clutch/drivetrain issue? Like a throwout bearing? Things like wheel bearings, u-joints, cv-joints, differential... those would tend to make noise/be louder when loaded, so the noise wouldn't stay a consistent volume. Exhaust leak of some kind? I would tend to think a noise from the driveshaft support bearing would vary with load/rpm. Everything look copascetic under the hood? Grab an inspection mirror and flashlight, see if you can see if the intake manifold gasket &/or manifold gasket is intact top & bottom.
Found and Fixed... It was indeed a wheel bearing of some sort on the right-front wheel. Had it fixed a few weeks ago, and we're back in business, sans noise. Thanks MGarrison!!
I just bought a set of those michelin primacy's, and they are awesome. The ride is so smooth and it handles great. These are great tires for this car. Love this machine!
