300SD boiling batteries/charging problems

[kartoffelpanzer]

Hello-

I've been lurking on this forum for awhile, just registered recently.

I have a 79 300SD (W116) that I'm restoring. I'm having what appear to be some battery/charging issues. Middle of last week I was driving on the highway, when I exited and stopped at a light I smelled rotten eggs/sulfur. Popped the hood and it was coming from the battery, which was spitting fluid/gas out the vent.

I replaced the battery and bought and installed a new voltage regulator (from mercedesshop). I fired up the car, went down to the auto parts store and had them recheck the charging voltage. They got something like 16.5-17V.

Do I need a new alternator? Is there anything else I should check?

Thanks in advance-
Rob

You definitely have a faulty new regulator or a bad alternator.

My old alternator did exactly the same thing. It would randomly run up to about 18v, sometimes for a few seconds and sometimes all day.

I'd get a whole new alternator, regulator and battery. Don't trust the old battery anymore.

[kartoffelpanzer]

Thanks Forced.

Forgot to mention age...I've only owned the car for the past couple of months and the PO (of ten yrs) didn't keep records. PO before that kept some records.

Body has 395k miles on it, motor was replaced and has about 150k miles on it. From what I understand, an engine replacement is engine and nothing more...so I gotta assume the alternator is original...

I've read that the alternators are strong but maybe not 395k miles strong

Rob