rdh3t Posted July 24, 2006 Share Posted July 24, 2006 Hi, I have an automatic transmission 2002 Subaru Legacy L Wagon,in good shape, under 50,000 miles. Recently it has been making an odd humming sound when I shut the engine off. This is a low pitched sound, steady (not vibrating or oscillating), and it can last up to 45 seconds or so with the car shut off and key taken out, until it eventually fades off to silence. I've never heard anything like this before it started a week or so ago, and I haven't taken it for service or anything--I figured I'd start here. Anyone have any ideas? Thanks, Ryan Link to comment Share on other sites More sharing options...
automaticsti Posted July 24, 2006 Share Posted July 24, 2006 not tryin to make you sound dumb, but is it the fan? Link to comment Share on other sites More sharing options...
rdh3t Posted July 24, 2006 Author Share Posted July 24, 2006 thanks, when it comes to cars, I will readily admit I am dumb. I will open up the hood the next time this happens to see if the fan is spinning. The thing that surprises me is that I know for sure it has never made this sound until the last week or so, even during a whole hot virginia summer last year. Is there a logical reason why this noise would start happening? I'll report back when I check to see if the fan correlates to the noise. thanks Link to comment Share on other sites More sharing options...
automaticsti Posted July 24, 2006 Share Posted July 24, 2006 thats what makes me think that its not the fan either...lemee know Link to comment Share on other sites More sharing options...
SLegacy99 Posted July 24, 2006 Share Posted July 24, 2006 45 seconds? This is a long shot, but my K & N air filter emits a hum that lasts for about 3 seconds after you turn of the engine. Any such modification on your Legacy? Link to comment Share on other sites More sharing options...
rdh3t Posted July 25, 2006 Author Share Posted July 25, 2006 Absolutely no moderations to this ride--strictly stock everything. Definitely 45 seconds, even closer to a minute. It seems to happen more often when the car is more warmed up and hotter, but even then, I watched the fan today--turning the car off with the key kills the belt's motion, the fan is spinning due to the motion of the belts, and it spins down within seconds--the length of the hum baffles me. It is totaly even and steady at a constant volume for most of a minute sometimes. Link to comment Share on other sites More sharing options...
Vimy101 Posted July 25, 2006 Share Posted July 25, 2006 The fan is electrically powered on smaller displacement engines in order to save weight/space. Link to comment Share on other sites More sharing options...
automaticsti Posted July 26, 2006 Share Posted July 26, 2006 can you pinpoint the exact whereabouts of the sound, bottom end? i take it Link to comment Share on other sites More sharing options...
rdh3t Posted July 27, 2006 Author Share Posted July 27, 2006 I'm going to sound like a tool here, but I have perfect pitch and the sound is consistanly a "G" two octaves below middle C--98 Hz--definitely a low pitched and steady sound. It definitely seems directly related to how hot the car is--if I just drive it a bit, there is no sound, the more I drive it, the sound appears, and the length of the sound is proportional to how much the car has been driven (and thus how hot it is). I think that the fan makes the most sense, though it hasn't done this in the past over hot summers. Maybe there is some sort of friction or something that is causing the fan to resonate at that frequency. Link to comment Share on other sites More sharing options...
Biff05LGT Posted July 27, 2006 Share Posted July 27, 2006 Pop the gas cap loose real quick and see if it stops. My old 91 Grand Prix makes a strange hum and that stops it. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.