300E Fail-Start Part Deux

As some may recall---I have a 1989 300E. Last week the belt tensioner was replaced and a few days later the car would not start. The battery was discharged. Jumped courtesy of AAA--and car started instantly. Benzmac---you mentioned alternator may be malfunctioning or possible voltage regulator. -----Well Saturday was driving and the episode occurred again. Jump-started right up. Went to local station they performed load test and swore---battery needed replacement. They said--alternator was charging. Went to get the battery and as a service---the store checked the charging system. They said no discharged battery could be used on a load test to determine the proper charge of alternator. They said the battery was toast------and replaced it under their warranty. They were adamant in----opinion---alternator not charging properly. --------QUESTION WHO THE H--L IS RIGHT! I REALLY DON'T FEEL COMFORTABLE WITH JUST THE BATTERY REPLACEMENT----BUT IS THE SHOP PUSHING FOR AN ALTERNATOR WHEN ONE IS NOT NEEDED.

[This message has been edited by Ammadeus (edited 06-07-99).]

There is a possibility that the voltage regulator has worn brushes & that they're at their limit. This can cause intermittant charging system problems. Its a small black box on the back of the alternator.

This is exactly what I was speaking of...Just like MB DOC said, if the brushes are worn the only way to know is to take them out and look at them. In most cases the alt. is not faulty it is the regulator with the brushes connected.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks guys----for your help. Simple solution then is to replace the voltage regulator. BTW-----I can't tell what amperage the alternator is? The car is 1989 300E-----

The car came w/80A from factory.

I am going to get the voltage regulator later today. From all indications---I should be able to install the new one myself without removing the alternator. Is this possible---or should I just let my shop do it for the $30.00? Thanks for all your help.