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  #1  
Old 01-28-2008, 09:04 AM
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I can hear my alternator in my radio

... it's a rebuilt alternator, from McParts (But it's a really nice local guy McParts, not a chain store McParts) - within the last year and a half.

Does that mean it's going bad or just that 21 year old wiring insulation isn't doing its job?

No reason to suspect failure, it's charging perfectly according to a multimeter. Just didn't know if that was symptom # 1 of bad alternators or symptom # 1 of old cars with old wiring.
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  #2  
Old 01-28-2008, 09:06 AM
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Check that the cable going into the power antenna is securely plugged in.
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Old 01-28-2008, 10:54 AM
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Do your headlights brighten if you step on the pedal at all? If so they I would try a new voltage regulator. It's on the back of the alternator, and there are two screws holding it in place.
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Old 01-28-2008, 11:05 AM
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Stock radio?
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Old 01-28-2008, 05:48 PM
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Inside the front wheel bearing caps were springs of some sort to negate this, many are no longer on the wheels.
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Old 01-28-2008, 05:50 PM
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Quote:
Originally Posted by toomany MBZ View Post
Inside the front wheel bearing caps were springs of some sort to negate this, many are no longer on the wheels.
I am voting with toomany MBZ Radio supression contact. I don't know how (why) that gizmo works but if you don't put them back in after you do your wheel bearing you will hear your alternator through your radio.
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  #7  
Old 01-28-2008, 07:43 PM
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If you can hear it when the car is not moving ( its wheels) then it is probably something else... check to see if you have any electrolytic capacitors either on the radio or on the alternator or wiring.... they leak and dry up over time.... and are often used in filtering circuits for this kind of deal.... on old plug in audio stuff...when this capacitor goes out you hear the 60 hrtz of the line voltage...
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Old 01-28-2008, 08:06 PM
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possibly a bad ground check all the grounds on the radio.
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  #9  
Old 01-28-2008, 10:01 PM
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Alternator whine in the radio can be caused by a failed diode in the alternator.
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  #10  
Old 01-29-2008, 09:07 AM
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Pay the extra $0.50 and use resistor spark plugs!





I'd start w/ that electrical grease on all grounds.
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  #11  
Old 01-29-2008, 11:01 AM
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My bet is you got a bad alternator. Did it whine before you put the rebuilt alternator on? If not, then it's the alternator. Rebuilt doesn't mean what it used to any more.

Is the whine affected by engine speed rather than driving speed, and does turning on the headlights, heater blower, and all electrical accessories reduce the noise? Then it's the alternator. Have a car that did the same thing, and changing the alternator fixed the problem. It still always kept the battery charged though. Suspect a diode but never got around to finding out for sure.
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Old 01-29-2008, 11:34 AM
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Wow, forgot I'd even started this. Crazy week...

anyway,

*It's an aftermarket radio, not the original. Less than two years old.
*The alternator swap was done well over a year ago, and the alternator puts out steady charging voltage. No reason to suspect it's bad. New voltage regulator went on when we put the alternator on.
*It is engine speed related, not wheel speed, that's how I decided it was the alternator in the first place. Nothing else electrical that's governed solely by engine speed.
*I haven't tried playing with the headlights and things in connection to it.
*It's not a really penetrating whine, just sort of a background whistle. The only time I hear it is if I'm listening to a weak station and therefore have the volume up too high. It may be this and nothing more rather than an electrical problem.

I'll keep an eye on it and check some of these things out. It's not a particularly pernicious problem yet, I just wondered if it was something that was universal.

Thanks, I'll report back if I find anything. Won't have time to check for a while.
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"What could possibly go wrong?"

~Michael S.~ -
1986 M-B 300SDL, retired due to rust and electrical problems. Donated engine to:
1987 M-B 300SDL, odo dead. New project.
1982 M-B 240D, odo stopped at 308,000
1982 M-B 300SD, 175,000
1989 Dodge Ramcharger, 87,000 - 4wd, 318
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  #13  
Old 01-29-2008, 03:30 PM
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I can hear my alternator in my radio

Just my .02 cents--- Were you hearing the alt noise while the radio was on the AM band or on the FM band or both?? Seems to me there are two possible routes for the alt noise to get into your radio. First, the alt noise can be radiating from the alt and being picked up by the antenna. If this is the case opening the hood could increase the response. (If the hood sheet metal is steel). Also disconnecting the antenna from the radio should decrease the response. The other source of alt noise might be associated with the power input leads to the radio. Sometimes it is possible to run the "hot" lead through a feedthru capacitor which is securely grounded. What I am assuming is that the alt noise has components that are in the radio frequecy band,and your radio is treating that noise as a legit radio signal. Oh well,just a thought.best of luck to you. Willie
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  #14  
Old 01-29-2008, 04:36 PM
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I have bigger fish to fry just at the moment. I was wanting to throw it out there but I don't really consider it my biggest problem at the moment.

Thanks for all the input, I've got a list of several things to check and rule out and figure out now.
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"What could possibly go wrong?"

~Michael S.~ -
1986 M-B 300SDL, retired due to rust and electrical problems. Donated engine to:
1987 M-B 300SDL, odo dead. New project.
1982 M-B 240D, odo stopped at 308,000
1982 M-B 300SD, 175,000
1989 Dodge Ramcharger, 87,000 - 4wd, 318
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