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bollbudb
My 1989 560SL will run for a distance of less than 10 miles, and the battery will be completely drained, barely click when ignition key is turned. Can anyone tell me, is this problem likely to be the alternator? The battery is in excellent shape, so that is not the problem. I will appreciate any input or advice.

I am fairly new to the forum, and this is my first post. Since this problem began, I parked the car and covered it, but really do miss driving it.

Thanks very much, everyone.

Wayne Bollman
 

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Jaguar STR-sold,mercedes s500L-sold,c36 amg-sold,s500 coupe-sold,cl420-sold,s320-sold,s280-sold
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bollbudb
My 1989 560SL will run for a distance of less than 10 miles, and the battery will be completely drained, barely click when ignition key is turned. Can anyone tell me, is this problem likely to be the alternator? The battery is in excellent shape, so that is not the problem. I will appreciate any input or advice.

I am fairly new to the forum, and this is my first post. Since this problem began, I parked the car and covered it, but really do miss driving it.

Thanks very much, everyone.

Wayne Bollman
Hi there,
Alternator will cause battery light stay on at all time, as it is not being charged.
I think you're on the wrong forum - w126's boys, over there could be a better help mate
 

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1984 500SL 000760
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Wrong Forum for a 89 560sl? That is a 107 not a 126, this is the correct forum.

And yes it sounds like your alternator is bad if the battery keeps discharging. If you can get it to a parts store they can confirm the altrnator is bad with a test.

Fill in your profile
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,330 Posts
Or voltage regulator. Easy to test. Connect a volt meter to the battery terminals. Should read 12.5+ volts. Start car. Battery should show 14.5 volts.+/- a little.
 

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1988 560SL (California Model)
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Probably is the alternator...replace or rebuild. I did the latter with mine. Great shop here in town...cost was about $90. Has worked great for going on 3 years now.

Also a quick and easy test if you have a volt/ohm meter. Set it for volts DC and test the battery with the ignition off. Should read 12 volts or a little higher. Start the car up and you should be getting 13+ volts on the meter. None or little change with the car running would indicate the alternator. Make sure all connection are clean on the battey.
 

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1975 450SL
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Just a few things to watch out for.

The highest likelihood is a failed alternator, possibly one of the internal components, such as the voltage regulator or diode pack.

That's assuming the belt is intact. Don't overlook the obvious, I've seen it happen.

If the alternator tests good, then there is a good possibility that your ignition switch has failed. The ignition switch has 3 parts to it; the lock cylinder, the shell/wheel lock, and the switch. All 3 are replacable with varying degrees of difficulty. The switch is not super easy, but it can be done by a guy with a few tools and some patience.

There is a wire from the switch to the alternator (usually green) that provides voltage to a section of the alternator that lets it produce voltage. ( I can get more detailed and technical, but it usually puts people to sleep)

If the switch goes, it often stops providing the voltage to the green wire mentioned, causing you to have to run the car off the battery, with no output of the alternator to recharge and run the car.

Also, check the connections to the alternator. A connector could have come loose, or the wiring could have corroded or broken.

What you describe is the classic symptoms of no output from the alternator. The "trick" is to find out Why. There's no sense in buying a new alternator when the problem is a bad connector.

Another word to echo an earlier recommendation: You can get your alternator rebuilt for a LOT less than a new one would cost. I had mine rebuilt by a shop in about 6 hours for about $80.00, but I had put a new brush module in myself a few months earlier, so that part wasn't needed. A new unit at the dealership would be $300.00 plus, a Remanufactured unit over the internet was $150.00 or so (plus shipping), but the rebuilder was recommended by a friend that knew a guy that worked there. Look in the Yellow Pages under Automotive Electric, and you might just be surprised.

One of the guys at the rebuilder was the one who told me about the "green wire from the ignition switch" problem. It is evidently common to a lot of European cars.

Good Luck,
Scott
 

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W221 & Audio Moderator
2013 S550
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How it got here

I think you're on the wrong forum - w126's boys, over there could be a better help mate
Wrong Forum for a 89 560sl? That is a 107 not a 126, this is the correct forum.

OK- the first two posts in this thread appeared in the W220 forum. I relocated it here, and failed to include a note - and unfortunately, since I'm not a mod in the 107 forum, I couldn't add it once it was here!
 

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1984 380SL
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My voltage regulator failed last year. The man asked me if my battery light had illuminated. I said no and he knew right then it was the regulator.

In your case the battery light DID illuminate, therefore it is probably the alternator.
 
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