[Lights]

My 300D's battery suddenly died, and jump starting didn't seem to charge the battery any. If it weren't for this forum and my reading about the symptoms of a worn-out voltage regulator several months ago, I wouldn't have know what to do.

I guessed that my alternator was stock and the VR on it original, so I took the alternator off and removed the VR from it. Sure enough, the brushes were worn down so far that the wires soldered to their bases were stretched tight on the other side.

Took a day to get a replacement part from Sparomobile in Downers Grove, IL (a great little shop, by the way), and after 20 minutes reassembling everything, she ran fine!

The only hiccup was one of the VR's screws sheared off as I was unscrewing it. I drilled into the busted shaft and tried to use a screw extractor without success. So I drilled all the way through the busted shaft and left the remaining metal as a sort of "sleeve" through which a smaller M3 bolt threaded snugly into.

Done and done. Thanks to all the great folks and all the great knowledge that's entombed here. This place is one reason why these W123s refuse to get off the road!

 

[kevdupuis]

This thread has made me wonder when if ever the voltage regulators have been replaced on both my 123 & 126, since I have to put in a parts order for the 126 I might as well order one for each of the Mercs to have handy.

 

[Forcedinduction]

I get about 5 years /60k miles out of my regulators before the brushes wear to the point I get charging issues.

 

[Aaron Faulkner]

Is the M3 bolt the right size for the VR? I removed my VR recently and because it brok when I took it out and the screws were badly worn, I threw the two screws and the old VR out and waited a day for the new one to arrive. Sadly the new VR does not come with screws and now I’m, well, screwed trying to find the correct size replacement. ? I have made a note-to-self to not throw the baby out with the bath water next time.

 

[Lights]

No. M3 is smaller than what you need. I don't know if M4 or M2 is larger. Order two of each just to be sure.

 

[Aaron Faulkner]

Thanks Lights!!! I do know that M4 is larger than an M3, the numbers increase as the diameter increases. Do you happen to know the length of the screw?

 

[cooljjay]

At this point in time, if the car has the original alternator...it is wise to buy a new one or get the lifetime ones....

The diodes go bad in the alternators, grease drys up in the bearings and the commuter will eat up a new VR is no time because of the wear to it...

If you have a alternator/starter rebuild shop...drop it off for a check up....