Voltage Regulator for 300E
 

Hello everyone,

I am thinking about changing out the voltage regulator on my car since I hear that it car leave you stranded if the brushes wear down too much....

My car is a 1989 300E, how do I go about doing this?

Thanks!

Hi Rahulio

Here is my description on a thread a couple of years ago about how I did it on my 1985 380SE. It turns out that I didn't really need to since the brushes (at about 125k miles) probably had many 10s of thousands of miles left on them...

I am assuming the your 300 has the same alternator as mine, I would get the new brush/regulator unit first and practice compressing the brushes before taking the old-but-functioning one out of your alternator!

Hal


......
There are some posts about how people have done this. Just thought I'd post mine. This is on my 1985 380SE. I removed the assembly from the back of the alternator. Removed two screws and popped it out - easy. Then had my "Oh S**" moment when I saw how fiddly it would be to put the new one in - to compress the brushes in particular. I tried tieing the brushes down with string, but at first couldn't compress them enough. Then I tried to fiddle it in with my fingers, no luck. So this farting around took about an hour. Then I tied the brushes down again, looping the string over the brushes and then around the outside (VR) side of the VR unit, and tying the string as tightly as I could. Then to make the string tighter I fiddled with it to go over the VR flanges. To make the string tight I think you could put some cardboard or pieces of popsicle stick to shim the string between the string and the unit body. The trick is to really compress those bad boy brushes down as far as they can go. With the string compressing the brushes virtually all the way down the unit went back in the alternator easily. Then I inserted and tightened the two mounting screws, cut the string and pulled it out using needle nose pliers.