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  #1  
Old 04-01-2008, 08:28 PM
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diagnosing battery discharge or alternator??

One other facts, the car has the 2.6L M103 engine. Purrs like a cat.

Well, 1987 260E won't start after parked overnight. I turn the ignition and nothing. No lights no nothing. I drive another car up next to it and jumped started the 260E. So it starts up and I drive it for about half an hour on the highway. Came back to the parking lot and hooked up my trusty multimeter(voltmeter) and it shows only 11.75V At first I thought maybe it was a the battery or something draining the battery overnight. But seeing the 11.75V at the terminal of teh battery made me suspicious the alternator might be shot. One other thing, when I shift from reverse to forward and vice versa
the intensity of the headlights visibly drop a bit and comes back on. When I step on the brakes it also does this, sounds like the alternator doesnt it?


Is there a foolproof way to find out which is which? I have a spare brand new voltage regulator for the alternator but I am scare of pulling the old one out fearing that I might not be able to put in the new one and worse can't put back the old one. The regulator has two springy legs that you can push into the body of the thing, but hte pring will push it back out if I let go of the finger.

Is replacing the alternator a very tricky thing on this car? I looked at the engine compartment and I can see the voltage regulator bolted onto the alternator, and its accessable to my hands and screw driver. I wanted to get some opinions before putting the wrench to the thing. Is my diagnosis fairly close as far as altnerator is concerned or something else? Thanks in advance.

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  #2  
Old 04-01-2008, 08:31 PM
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I forgot to mention. When the car was running I hooked up the voltmeter and it
shows 13.75Volts.

Quote:
Originally Posted by throne7 View Post
Well, 1987 260E won't start after parked overnight. I turn the ignition and nothing. No lights no nothing. I drive another car up next to it and jumped started the 260E. So it starts up and I drive it for about half an hour on the highway. Came back to the parking lot and hooked up my trusty multimeter(voltmeter) and it shows only 11.75V At first I thought maybe it was a the battery or something draining the battery overnight. But seeing the 11.75V at the terminal of teh battery made me suspicious the alternator might be shot. One other thing, when I shift from reverse to forward and vice versa
the intensity of the headlights visibly drop a bit and comes back on. When I step on the brakes it also does this, sounds like the alternator doesnt it?


Is there a foolproof way to find out which is which? I have a spare brand new voltage regulator for the alternator but I am scare of pulling the old one out fearing that I might not be able to put in the new one and worse can't put back the old one. The regulator has two springy legs that you can push into the body of the thing, but hte pring will push it back out if I let go of the finger.

Is replacing the alternator a very tricky thing on this car? I looked at the engine compartment and I can see the voltage regulator bolted onto the alternator, and its accessable to my hands and screw driver. I wanted to get some opinions before putting the wrench to the thing. Is my diagnosis fairly close as far as altnerator is concerned or something else? Thanks in advance.
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  #3  
Old 04-01-2008, 09:03 PM
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Join Date: May 2006
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Get your alt checked out, how many amps is it putting out. 13.75 with engine running sounds normal though. If battery resting voltage is only 11.75, its too low, get a new battery. My 190e has a rest voltage of 12.5 after sitting overnight. I dont really drive it too muc anymore so I have a Battery tender to hold the voltage around 13 volts when hooked up to car.
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  #4  
Old 04-01-2008, 10:32 PM
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Join Date: Jan 2008
Location: Redondo Beach, CA
Posts: 188
Since you have a replacement voltage regulator, why not try it? You can tie the brushes back with dental floss, install it, cut and pull the floss out. Once you get it started, drive to an auto parts store that can test your battery. My VR went bad and I was getting 13.25 volts at idle, but it would drop to 10 or less at 2k rpm, its a cheap test, and if it is your battery you won't be any worse for changing the VR.

That's my 2 cents
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1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K
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  #5  
Old 04-02-2008, 03:29 AM
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Quote:
Originally Posted by riorust View Post
Since you have a replacement voltage regulator, why not try it? You can tie the brushes back with dental floss, install it, cut and pull the floss out. Once you get it started, drive to an auto parts store that can test your battery. My VR went bad and I was getting 13.25 volts at idle, but it would drop to 10 or less at 2k rpm, its a cheap test, and if it is your battery you won't be any worse for changing the VR.

That's my 2 cents
Thanks, I think i will try it. I like the floss trick. I was wondering just now how to hold the spring loaded metal connectors in so I can push it into the alternator body.

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