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My car is making some weird noise....

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Old 03-06-2008, 04:35 PM
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My car is making some weird noise....

Usually if I'm driving downhill or on the freeway, my car makes a fairly loud, high-pitched squeaking sound....exactly like feedback you'd hear from a microphone. It can't be my brakes either since I'm not even stepping on it.

What could the problem be? My dad's gonna try to take it in and have it checked by this weekend.
Old 03-09-2008, 10:10 AM
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I have the same thing going on my 03 e500. When im at about 70 and i let off the gas, i get that microphone sound too (but not real loud). I've had it for the past year but i haven't really worried about it because the volume on my stereo is louder so it drains out. I wonder if we need to clean the throttle body (butterfly valve)?
Old 03-09-2008, 05:25 PM
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Possibly the differential, have you tried changing the fluid? It should be done anyway, so no loss if it does not cure the problem.
Old 03-09-2008, 09:45 PM
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To be perfectly honest I'm a complete n00b with cars, so while some of the terminology sounds familiar to me, I really have no idea what part names are.

Another thing: it tends to get really loud if I'm driving down the big hill I live on....and if I just accelerate or go a little faster, the sound goes away. These past several days it had completely stopped though.
Old 03-09-2008, 10:45 PM
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Sounds like the rear differential. Change the fluid and see if that helps but sounds like it might be going out on you.
Old 03-10-2008, 06:21 PM
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BMW E30. I've turned to the dark side.
need more info: what model car do you own and how many miles are on it. also, when does it happen, hot? cold? louder in the front or rear of the car? does it change when turning or braking?

it does sound like differential noise although in 8 years with benz i've seen maybe 2 have this issue- most likely after a tech over-tightened the pinion nut. could be in the trans as well, although less likely. if you have a higher mile car, service both.
Old 03-11-2008, 03:52 AM
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It's just a '98 C280, and it sounds like it's coming from the front. I've only noticed it when I'm usually going in a linear direction (usually downhill), but lately it hasn't made any sounds. I do get an occasional 2-millisecond "eee!" but that's it.

The weather has been much warmer lately, I don't know if that has anything to do with it.
Old 03-16-2008, 09:02 PM
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EXACTLY the same with me. When it gets warmer it seems to go away. The noise is definately coming from the front (like where the air box meets the air inlet (butterfly valve area)). The dealer "Could not dupilcate" and i wasn;t getting any warning lights, so i never thought it was too bad.
Old 03-20-2008, 12:01 PM
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BMW E30. I've turned to the dark side.
green apple: not a diff- obviously, that would be from the rear of the car and would be a much more constant whine. you could have a bearing going out on either the h2o pump, ilder or alternator. these seem to be worse when cold- my neighbors can hear the t/o bearing on my 510 when its cold in the morning-. either way, don't just start thowing parts at it. when the noise gets more consistent, have a dealer look at it. also try to determine if the noise is engine speed or speed of the car (like a brake noise) change gears when it happens, slow down, speed up, mix it up a bit to help isolate what the cause is.

merc500:
without actually hearing your noise, i would still guess that is if it only occurs when the car is cold, or occasionally when warm, it is a normal air release for your airmatic system.
Old 03-20-2008, 09:19 PM
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Originally Posted by benz-tech
green apple: not a diff- obviously, that would be from the rear of the car and would be a much more constant whine. you could have a bearing going out on either the h2o pump, ilder or alternator. these seem to be worse when cold- my neighbors can hear the t/o bearing on my 510 when its cold in the morning-. either way, don't just start thowing parts at it. when the noise gets more consistent, have a dealer look at it. also try to determine if the noise is engine speed or speed of the car (like a brake noise) change gears when it happens, slow down, speed up, mix it up a bit to help isolate what the cause is.

merc500:
without actually hearing your noise, i would still guess that is if it only occurs when the car is cold, or occasionally when warm, it is a normal air release for your airmatic system.

Benz-tech:

When we meant that when it gets "warmer", we meant warmer weather, not warmer car temp. I dont think it's the airmatic at all becuase it would "eee" more often and even at stop and city traffic.

This problem we are having is related to when we left off the gas pedal at highway speeds. Mine does it when im at 75, left off the gas, and the car eee's to 70 mph and then the "eee" goes away when it goes below 70 OR when i put my foot back on the gas pedal. So my best guess is the air intake system. My guess is that when the butterfly valve is letting in air at from 75 to 70 it is closing up (because less gas is entering the engine = less air = close butterfly valve a little bit more). So maybe the "eee" is a whistling sound from the valve which probably needs to be cleaned or adjusted. Does any of that make sense to you?

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