>        My radio has started picking up the whirring sounds of the engine.

It occurs to me that back in the olden days, manufacturers installed
much better noise suppression circuitry, because AM receivers are much
more sensitive to interference than FM.  I'm sure many of us remember
driving at night and picking up AM stations from hundreds or even a
thousand miles away.  Try it now and you find your AM overwhelmed by
ignition and alternator noise.  Car makers think that people are only
concerned with FM  now because more of the population is in urban areas.

Larry A.