2.3 16V Intermittent Battery drain when driving, Alternator OK

It seems that on my 85 Euro 16V, the battery drains intermittently when I drive it. Battery does not drain when car sits for prolonged periods. When I drive I can see the volt meter start to drop, then it will jump back up above 12V. A few times the volt meter has gone all the way to zero, tach starts to jump and car stalls - completely dead, usually when I am not near my home in Boston. I charge the battery, car drives fine for a few days and then- same thing happens.

Replaced the battery and had the alternator checked (58 amps) by dealer. Seems ok. Problem is, this is an intermittent problem that happens maybe twice a month - and wouldn't you know it never happens when the dealer has the car.

Could it be the regulator in the alternator or a loose connection somewhere? Anyone had this problem before?
Dealer has seen this car twice and problem still remains.

Any advice would be greatly appreciated

mrossipir@yahoo.com

[G-Benz]

Do you have an aftermarket alarm system? I had one in a former car where the alarm brain would sometimes suck the battery dry! Yanked the unit out and never had a problem since.

Check your battery cells (if yours is not the sealed type) to make sure each cell has electrolyte in them. Add distilled water until the water level covers the plates.

Check the alternator for loose connections. I believe there are two...a larger primary lead, and a smaller possibly ground wire. That may be why you see voltage drop, then come back up, as the car vibrations cause the charging lead to be connected and disconnected at times.

It could be as you stated, the voltage regulator.

The regulator on some models is external and can be replaced separately (and WAY less expensive than a full alternator replacement). Otherwise, if you have the internal regulator, you may have to get the whole thing replaced or reconditioned at an alternator shop.

To me really, it sounds like the alternator is on its way out. Problem could be intermittent, and later, occur more frequently until...total failure!

I once had an alternator checked out to be in good health at a local service station one week before I ventured out on a road trip. By the end of the trip, it completely died!

IF YOUR VOLTAGE REGULATOR IS SUSPECT REPLACE IT. IT'S CHEAP AND EASY!
DIDN'T NOTICE YOUR LOCATION BUT IN OUR LOCATION (CAL. HIGH DESERT) WE SEE A LOT OF DISCHARGED BATTERYS FROM EXCESSIVE CURRENT DRAW FROM A/C SYSTEMS.
A/C BLOWER 28 AMPS
CLUTCH 8 AMPS
AUX. FAN 25 AMPS
ON THE LONG RUN YOUR ALT. WOULDN'T KEEP UP!
MF

[vutown]

Villiage Idiot,

My '85 190E had an alternator problem. It seemed as if its output was getting weaker and weaker as time went by. I would have to guess that it started a few weeks ago, where my alternator would slowly die, draining my battery.( almost new)

I ran one particular test: I started the car up, ran it for a few minutes, and disconnected the battery. In theory, the alternator should be strong enough to power the whole car. When I disconnected the battery, it ran fine till I turned on the headlights. It felt as if someone had turned the ignition off.

I changed the alternator, and ran the same test. This time, with the battery disconnected, I turned on the head lights, all of them, hi-beam and fogs. Not a glitch!


If u plan to keep the car for a long time, changing the alternator would be best. It bets being stranded!

-Regards,
Vu

Vu;
Disconnecting the battery cable while the engine is running is not a good idea!
Without the battery in the circuit alternator output can exceed 20 volts,you may damage some expensive electronics.
M.F.

[vutown]

Mike,

Ouch! Thanks for giving me a heads up on it. I didn't run the car w/o the alternator for too long, I think not. So the way to test the alternator would be to test the battery terminal while the car is running to see if I get 13.5+ volts?

Thanks!

Vu

[Benzmac]

I had a similar problem with my 16v and I replaced the alternator. It fixed the problem....The new one puts out more amps and more voltage shows on the volt gauge.

REPLACE THE ALTERNATOR!!!

[JDUB]

Connect a voltmeter to the battery when the car is idling. If the voltage reading is not between 13.2 and 14 volts,then you need alternator service period. You can by a non-Bosch brushholder assembly for about $15 and replace it in about 15 minutes or buy a complete rebuilt alternator for about $175.