Started car, went to library, left library, car dead??? - PeachParts Mercedes-Benz Forum

DieselHead · #1 10-26-2002, 03:15 PM

Hey,
THis morning I went to the local library a mile away, and when I got back to my car, it wouldn't start! What gives? When I switched the key to the "on" position, the Tach flipped out and there was an awful groaning noise. Some came to give me a jump so now the car is in the driveway and being charged.

Does anyone know what might have caused this? As far as I knew, the battery was ok (it's an Interstate that's about 3 and a half years old) and I think the alternator is also ok. My car was just at the mechanic to get all the fluids and fan belts changed yesterday. Could there be a short somewhere that's draining the battery? Is the battery a dud?

Any advice or info would be much appreciated. I'm afraid to take this car anywhere now not knowing if it'll start up again. Oh, eventhough the car wouldn't start, the lights and stereo worked just fine.

Also, I noticed that on my way back, the ACC fan blew fast on the "slow" setting, normally on the "auto" setting, and not at all on the "high" setting. Thanks!

Alex

#2 10-26-2002, 03:21 PM

Might want to get the battery checked, you might have an internal short in the battery like I did.

84300DT · #3 10-26-2002, 05:57 PM

battery and/or maybe alternator brushes like a lot of people have had go bad lately here.
also are your battery connections good?

#4 10-26-2002, 05:58 PM

After the battery is charged, put a DC voltmeter across it. It should read about 12 volts. Then start it up and put the voltmeter across the battery again. It should now read about 13.5 or 14.0 volts. If it does the alternator is putting out and the battery is at fault or there is a short that is draining the battery.

To check for a short, turn everything off and put an ammeter in series with a battery cable. It should read very close to zero amps. If it reads more than about 50 milliAmps, you need to start disconnecting things while watching the ammeter. Start by pulling fuses one by one. When you pull one and the ammeter goes to zero, that's the draining circuit.

If with all the fuses out it still has current draw, start disconnecting circuits until you find the draw.

Good luck,

#5 10-26-2002, 08:45 PM

Alex, no doubt, you and everyone else overlooked the obvious... don't go to the library! Works for me!

You can go to any of the fast food type of auto parts stores and they will bring their testing equipment right out to your car and do a bonafide load test on the battery. A volt meter will only give a you an idea if there is voltage present, and your radio and other low load gizmos have no problem operating on a goonie battery.....under a real load....things change.

Ernie

psfred · #6 10-26-2002, 09:42 PM

If you could jump start it, the battery was low. Check charging system (load check is best) and if OK, replace battery.

MBs do strange things when the battery is low -- cranking a W126 with a low battery makes the wipers do a single wipe, for instance, and the AC will go nuts.

Peter