I've had good luck with the local O'riley auto parts places for charging system and battery tests, though the parts monkey has occasionally been less than fully helpful when testing a diesel engine's charging system.

The different stores of that chain in this area all use a large computerized battery charger/tester which seems to take a good bit of the skill of the employee out of the equation.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...

a parts place test is fine. But its just one test. For 15$ a digital multimeter can be had and you can test your charging voltage anytime while driving down the road by putting the leads in the cig lighter.

Charge the battery, test voltage
Start Car, Test voltage
Wait 60 seconds, test voltage
Pull on linkage and raise rpm, test voltage
Drive down the road for a while, test voltage

If you are getting constant 14 volts I doubt its the alternator.

I dislike electrical problems.

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77' 300D, "Cartman" SOLD @ 150K (didn't know what I had)
83' 300SD, "The Superdon" 325k+ @ 28mpg
95 E320 wagon, "Millennium Falcon" 231k+ @ 24 Mpg
95 E300D, "Sherley" 308k @ 33.69 Mpg, currently anticipating a head
99 Suzuki Intruder "Trudy" @ 45 mpg

You can get a reg for 8 bucks... just do it already

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

If your cluster wiring is wonky - your alternator will stop charging completely - the bulb for the battery warning is the excitation circuit.

where are you sourcing 8 dollar voltage regulators?

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Local electrical rebuilder . $7.95 sucka, I have one on my 240d and im back up to 14.5 volts after the last one blew up the battery and commited suicide (which is btw how i got the car). Or maybe the battery commited suicide and took the reg, i suppose the world will never know.

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

I took out the regulator I think. I assume it's bad since the copper things(brushes?) are different lengths. Take a look and let me know what you think. Thanks.

Attached Thumbnails

 

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"Gerwalt" 1984 - 300TD

That looks like the problem, that one brush is completely worn out. Pick up a new voltage regulator and you should be good to go.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Yes, that looks like the problem.

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Gone to the dark side

- Jeff

no...
sorry. the problem is not just a regulator...
look at the short brush. it's got a groove in the middle... that means the armature needs to be turned, it's gotten damaged.
if you put in a regulator, it'll be in the same shape in little time.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

While the brush is damaged i see no reason to not just toss a new one in. you will have had to kill 8-10 before their cost will exceed a new alt. and by a short time i would imagine 50-60k and unless the op is rich a reg will give him a band-aid until finances say go blow some money on your benz!

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car

I would buy a new alternator with the new regulator, then of course give 'em the 'core' and be done with it.

Thanks for the picture of the old regulator and thanks, John (vstech) for the edjumacation here!