KC420

Hi guys,

in my E420, i keep having the noise coming from the alternator/generator (lichtmaschine in germany). it has nothing to do with false audio wiring install or what not, as checked by pros.
so, the problem is: even without a radio installed, i have the distortion sound from the generator/alternator meaning rpm dependent & hearing gearshifts, through the speakers. of course, linking up an HU only amplifies this sound.
the audio pros cant figure it out either, and mention i may have an electrical problem with the car itself.
Question to the forum experts: did anyone have similar issues? would replacing the alternator/generator fix the problem?
i am going crazy from this noise.....
thx for yr help!

RobertG

I've experiences this before but not on a Benz, yes it was the alternator. To be more specific, it was one of the diodes that went bad.

KC420

robert, thanks for that input.
i am hoping to hear from people that had a similar problem, and what the solution was.
u know how it goes otherwise: i get "professionals" to "look for" the problem, which takes them a couple of hours for which they charge me mucho euros, then they tell me i need to replace part X and Y, which costs even more mucho euros, adding again on the working hour fee... and in the end, with my luck, the situation is just as it was in the beginning (except me then being broke).
so you say replacing the alternator from your prior experience solved it?
would you recommend new or used?
this replacement is not like a tire, so i can't do by myself, and seems like a mechanic would need some time doing so also. any idea how much time it would take?
appreciate the help! cheers

RobertG

Last year I replaced the alternator on my 210 with a new one because a rebuilt was not available at the time and it would take a couple of days to get it, so I bit the bullet and went for the new one. The reason I replaced mine was because it was not charging and my wife needs the car everyday.
The wining noise that I've experienced was on GM vehicles, I used to turn a wrench profesionally at a GM dealer, it was not a common problem and the fix was to replace the alt or the diodes .
Did you modify your car with a new radio?
If you did then it would be cheaper to install a noise suppressor and be done with it.

KC420

hi robert, thx for that input
audio system was checked by "pros" but to no avail.
special electric distortion filter was tried, yet, no change
i really feel like it is the alternator itself, just trying to find somebody who had same issue, along with the fix that solved it.
i ll look at a used alternator (whole unit includes the diodes i presume) in mean time to be safe..takes long to swap (rel dealership houly wages...).
cheers

liebeskind

It's not a small job to do the alternator. I believe you will have to drain the radiator and take off the bottom hose to get the alternator off. It looks pretty tight in there. While you're doing the job, be sure your belt is OK. If not, replace it too.

Hirnbeiss

The diodes are part of the voltage regulator (regler), which you can replace yourself on the back of the alternator. ATU probably carries the part.
Note that electromagnetic interference is often caused by the spark plugs or plug cables. Are yours the factory recommended parts?