Since it has gotten colder in the last month, my '80 300D has had a dead battery a few times. Once the car is jumped it runs fine but then doesn't seem to have enough power to start again the next time.

I went to start it Sat. and had to jump it. It ran fine and started again Sat. night when I came home. Sunday I had to jump it, it started and then ran fine after a jump. Then last night when I went to drive home, it wouldn't start. Called MB roadside service and they came out, jumped it, and it started right up. I just went out and checked this morning and it won't start.

What could be causing this? We have had temperatures down in the low 40s. It just doesn't seem to have enough power to turn the engine over on a cold start when it is cold. The alternator was replaced this past Aug. and a new Interstate batter was installed.

Make sure your glow plug relay is working properly. Sometimes they will latch on and not release when the pre-glow time is done. This will eventually drain your battery.

I've had them fail this way on a couple of vehicles.

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Joe

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1980 300SD - 495k miles - 'The Ambassador'
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Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

While a long shot, could be a bad battery still. What I would try is disconnecting the battery and see if it dies over night. If it is still up and fresh, then I would look carefully at what the alternator is putting out. Just because it's new, doesnt mean it may not have failed. Should have 13.5-14.6 volts accross the battery when the engine is running. While it's possible the glow plug relay is hanging up, I would imagine it would burn out the glowplugs over this length of time. If you have a voltmeter to check the battery, put the lead on the glowplug and the block and make sure it is zero. Other things to check are lights staying on, or any aftermarket stereo amplifiers not shutting off. Keep us posted.

Found out what was going on.
The battery was fine as was the alternator. It was the clock, it was pulling 9.2 v ??? when the car wasn't running. The alt was charging at 13.9.
So I guess the solution for now is the pull the clock fuse. Is this just need to be rewired? The clock was working fine.

? How big is your battery? How old? Any battery over 4 years is suspect and when it starts to act like this its junk.
Your car wants a group 49 battery which is a monster. My test at the autoparts store is if I don't get a hernia lifting the battery its not big enough...

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Sadly Benz-less

Since the clock is always on is should be getting voltage constantly. You would want to see how much current its drawing(amps), not volts. Do you mean it is drawing 9.2 amps?

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'83 300D 198,000mi Howard
'03 Saturn Vue CVT 75,000mi(wifeys)

Since one amp would start melting the instrument panel he couldn't mean amps. Anyway the clock really can't be an issue. Current draw enough to drain the battery overnight would be blowing fuses and melting things.

The clock normally gets battery voltage at all times, so if it's getting 9.2 volts when the car isn't running, that sounds like a battery problem.

I have a current drain on my 240D that I haven't gotten around to fixing. I probably should since I only drive it every three days, and I've been having to jump start it ever since I replaced a bunch of fuses and got things working "right".

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I think thats what he said on the phone, I was half involved with something else here at work. I'm picking the car up today so will get the exact details.

I had a new alternator and battery put in in Aug. The old battery was an Interstate and was replaced with an Interstate Megatron 850 CCA. That new battery was exchanged out as it wasn't holding a charge.

do you have any aftermarket accessories possibly hooked into the clock fuse? Cell phone, Amp etc? I have never seen a clock drain a battery over nite. Very wierd.

I'm surely no expert but I can't imagine the clock pulling 9.2 volts. I would think it would burn up long before it would drain the battery overnight.

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Darrell

1984 300SD "Ole Girl"
207K