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  #1  
Old 09-09-2010, 04:16 PM
JHZR2's Avatar
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Location: New Jersey
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Now no alternator

So my 82 had a weak alternator, was giving 12.8v under load. Drove it 150 mi last night in the dark, ac headlights etc all were fine... This am, 11.8v. Alternator won't charge, no alt light at all...

Swapped bulbs, no dice.

Fortunately since it's a diesel and daylight I can drive home without - 11.8v operates brake and turn lights.

But what does it mean with no charge and no alt light?

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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)
1996 Dodge Ram CTD (438k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #2  
Old 09-09-2010, 04:30 PM
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First things I'd check is the voltage regulator. And that all your connections are tight.
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  #3  
Old 09-09-2010, 04:54 PM
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Just add Diesel.
 
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Location: Salt Lake City, Utah
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I had the same problem last week. Alt not charging and alt light not coming up. This is what I did: I got a multimeter and a schematic of my charging system and tested the battery voltage with the engine off, on and at more or less 2000 RPM, same flat 12V every time. I checked to see if there was continuity from the alt to the battery, no continuity. I then checked every circuit to make sure that it wasn't some loose wire or a faulty bulb. I was told that if the bulb is shot the alt won't charge. Beats me why, but I checked it anyways. All my wiring checked out okay. So I ordered a new alternator online and it's on its way. I really made sure that it was the alternator that was faulty before ordering one.
I had charging problems a month before and it turned out to be the regulator. I'd check that too as it's cheaper and easier to install.
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1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang"
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1983 Toyota Tercel (Tommy, The little Toyota that could)
1965 Ford F100 (Grandma Ford)
2005 Toyota Sienna (Elsa, Wife's ride)


Gone:
1988 Toyota Pickup
2004 Subaru Outback

1987 Cadillac Fleetwood Brougham
1986 Volvo 740 GL Station Wagon - Piece of junk.
1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P.
1987 Pontiac Fiero GT
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  #4  
Old 09-09-2010, 06:45 PM
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The free autozone test claims regulator. Would that keep the light from coming on?
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)
1996 Dodge Ram CTD (438k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #5  
Old 09-09-2010, 07:13 PM
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Quote:
Originally Posted by JHZR2 View Post
The free autozone test claims regulator. Would that keep the light from coming on?

Did they Test the Alternator while it was still on the Car or was it tested on a Bench.

If I had this issue I would have a preference for the Bench test because it eliminates any of the wiring/bad connector issues that also could cause the same problem.

Several of the Members have said when one or both of the Brushes on the Voltage Regulator were worn their Battery died and they saw no Battery Light go on.
If I remember correctly if the Brushes are worn 2MM or less they are no good.
I suppose the Brushes could be sticking out more and still not make contact if the Silp Ring was worn deep.
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  #6  
Old 09-09-2010, 07:26 PM
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A little long winded but there is some info.
http://www.humanspeakers.com/audi/alternator.htm
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  #7  
Old 09-09-2010, 07:39 PM
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Not bench - just on the car, I was 150 mi from home.

Will pull the EEG tonight and see, if it looks ok I'll pull the alt.
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)
1996 Dodge Ram CTD (438k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #8  
Old 09-09-2010, 08:00 PM
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[QUOTE=cirrusman;2541558]I.... I checked to see if there was continuity from the alt to the battery, no continuity. .....QUOTE]

You need continuity from alternator to battery.
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  #9  
Old 09-10-2010, 12:01 AM
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Well, found my issue... Put my car up on ramps when I got home (in the dark), after driving all the way home. That is what I love about diesels... I could drive my battery down to 9V (granted it is likely ruined, I have it charging), no alternator, and make a 150 mile drive home. Try doing that with a gasser...

Anyway, wanted to pull my voltage regulator to get a feel for the brushes and what was going on there. As soon as I unscrewed the screws and pulled it out, one brush fell out. It felt as if there wasnt even a wire in the insulation for the connecting wire for the brush...

The one was also worn funny compared to the other.





So I need to get a new regulator and then hopefully all is well. I am going to try the Altrom / Beru brand from Napa (their prices on regulators are horrid) instead of bosch because the beru is a 14.2V regulator versus the bosch at 14. Given my experience with these older cars and what the bosch alternators put out (my 91 BMW included) a slightly higher regulator helps keep the battery better charged.
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Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)
1996 Dodge Ram CTD (438k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #10  
Old 09-10-2010, 12:46 AM
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Dont throw that old reg out. It probably only needs new brushes. solder new brushes in & keep it for when the new reg fails.
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1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
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  #11  
Old 09-10-2010, 10:07 AM
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Just add Diesel.
 
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Quote:
Originally Posted by funola View Post
You need continuity from alternator to battery.
Yeah,I Know, that's why I ordered a new alternator...
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[/SIGPIC]~cirrusman

1983 Mercedes Benz 300SD - Wife calls him "Chitty Chitty Bang Bang"
[SIGPIC]




1983 Toyota Tercel (Tommy, The little Toyota that could)
1965 Ford F100 (Grandma Ford)
2005 Toyota Sienna (Elsa, Wife's ride)


Gone:
1988 Toyota Pickup
2004 Subaru Outback

1987 Cadillac Fleetwood Brougham
1986 Volvo 740 GL Station Wagon - Piece of junk.
1981 Volvo 242 DL 2 Door - Hated to see it go. R.I.P.
1987 Pontiac Fiero GT
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  #12  
Old 09-10-2010, 12:29 PM
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Join Date: Apr 2006
Location: Birmingham, AL
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I had exactly the same problem about a year ago. The alternator light/battery light on the instrument cluster is not coming on when I turn the ignition key to ON position, and at the same time, my battery is draining which means the alternator is not charging the battery. The bulb is good, the fuse is good, the voltage regulator is good, and the overvoltage protection relay fuse is also good. I finally replaced the alternator and fixed the problem. I had that old alternator bench-tested at AutoZone and their tester determined that the alternator diodes are bad.
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  #13  
Old 09-10-2010, 12:34 PM
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Yeah I learned that diode lesson on my BMW a few years back...
__________________
Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)
1996 Dodge Ram CTD (438k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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  #14  
Old 09-10-2010, 01:16 PM
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I also have experenced this: worn brushes = no charge and no alt light.

The first time my TE stranded me, when about 4 years old.

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