Voltage Regulator Replacement

[J. Huber]

Hey guys. So I recently had a situation when my battery (6 months old) went from weak to kaput while taking a drive. Initially thought, lousy battery. The shop where I bought it put it on charger for a day -- tested all good, including under load. Then we checked alternator which tested horribly -- leading me to have a mechanic friend pull it and see about brushes, etc. However, it checked out fine -- thus leading him to diagnose a faulty Voltage Regulator... Think mine is the original Bosch which I see either out of stock or out of sight! 

Has anyone switched over to the Beru or the Hella. I also wonder if these units (which look about the same but are dirt cheap) will work on the 230SL? I asked my guy if I had 35 or 55 Amp -- he thinks it reads 50? So if VR says compatible w/55 should we be all good?

Thanks
James

[roymil]

Hi James,  My original Bosch regulator failed in a similar way and I switched over to the much less expensive Beru and its been working out just fine keeping the battery fully charged even on short drives.    I have a 280SL but expect the 230SL could use exactly the same one based on principle of operation, although thats easy enough to check.  I kept the Bosch case around in case I ever wanted to stuff the Beru guts inside it to at least look original.      regards, Mark

https://www.autohausaz.com/pn/90160320602

[Jonny B]

I would echo the comment. I swapped out the old regulator for a solid state one, and I did replace the case cover and got yellow tape so it looks just like the old one. No further issues.

[sandcrab59]

Jon
Which one did you purchase?
Tom

[Jonny B]

I need to do some checking in the maintenance files. Will post what I find.

[Jonny B]

I read through my files and found that I had changed the voltage regulator in February 2013. It was a solid state unit (there were also issues with the alternator that were corrected - some bad wiring).

Unfortunately no note of the brand - I am guessing it was Bosch.

[J. Huber]

Just a quick thank you to those who replied. I bought a Beru replacement Voltage Regulator for about 25 bucks. I really wanted to partake in a MB Club drive over the weekend (and parcel was still on it's way) but I lucked out. I still had the original Bosch in a box of old parts -- I had changed it way back when I refurbished my engine bay -- because it looked tired. However, turns out it still works! So now I have a spare... The car drive through the California Gold Country was great! 18 MBZ vehicles of all shapes and sizes -- mine being the elder statesman.

[Kevkeller]

Sounded like an awesome ride. That’s beautiful countryside.

[mauro12]

Hello guys , this voltage regulator fits all w113 .? Also the 250sl ? Is the only alternative for the incredibly expensive bosch part?

[lpeterssen]

Dear Mauro and MB enthusiast

Yes, the BERU Voltage regulator suggested above by ROYMIL (https://www.autohausaz.com/pn/90160320602) will work with any size MB alternator as long as the connector is the same.  If connectors were different also by retrofiting your harness with a different connector the issue will be solved.

Best regards
Lp

[mauro12]

I have the original regulator and alternator. I guess is the only alternative because the bosch one is untouchable.

[Figoulu]

Question i was wondering myself…

The recent alternator for most of them have an integrated voltage regulator. I guess then the beru/Bosch voltage regulator  is useless ?
Anyone to confirm ?

When purchasing my pagoda this little device was alone and disconnected…

[Figoulu]

Anyone to answer on my last question ? 😅

[BobH]

Have a look on here, there are pictures of original and replacement alternators with and without integral regulators.  If your car has no charging problems, it must be ok or you would have known about it

https://www.sl113.org/forums/index.php?topic=3477.msg23547#msg23547

[lpeterssen]

Question i was wondering myself…

The recent alternator for most of them have an integrated voltage regulator. I guess then the beru/Bosch voltage regulator  is useless ?
Anyone to confirm ?

When purchasing my pagoda this little device was alone and disconnected…

Dear Figoulu

Yes that is right,  if you replace your original 35A alternator with a newer one from Bosch like AL69X which has exactly the same form factor as the original, the external voltage regulator is not needed.

You will disconnect in that case the external voltage regulator, on the regulator side, and on the end that goes to your original alternator which has a three prong cylindrical terminals connectors, you will take out the lead which is RED/BLUE.   Change the terminal type to this particular cable to match the terminal type you have on the new BOSCH AL69X alternator (normally is a "o shaped").

And that is all you will need to do.

Of course if you want a more appealing harness, eliminating what is not needed and upgrading the charging capacity of the loom, then you will have to contact a guy like me who do refurbish and retrofit Mercedes classic wiring harnesses.

Nevertheless remember that if alternator is changed to a new modern one, it is "a must to increase wiring charging capacity", as more current is produced 80A, vs 35A, and you need to have the correct pipe type (Cable size) to let that current travel to you battery.

Best Regards
L.Peterssen
 

[Figoulu]

Thanks for your useful answers 👍👍