Hi to everyone,

I'm the proud owner of the 1982 200 M102 with stromberg 175 carb, not a common setup in US but anyway problem is electric related so one of W123 diesel owners should be able to help, i suppose electrics are similar....

when i drive at night if i use an item such as heater fan or winscreen wipers in addition to main beams all the lights go dim and my pioneer cd turns itself off due to low voltage. It also happens when i hit the brakes the moment i touch the pedal i can see mainbeams weaken in front of me together with instrument cluster lights, so i did the following;

1-Battery (6 months old Bosch) at rest =12,2 V
2-Idle =13,2V
3-Engine@3000RPM=13,4V
4-Battery terminals, battery ground, engine ground strap all clean and tight
5-Current draw engine off= 90mA, when fuse 2 out=0mA

any suggestions?

thanks in advance
Umut

This sounds like either a shorting problem or lack of voltage. By your readings you are getting adequate voltage, so it may be an intermittant problem. They are never fun to find.

Maybe the alternator brushes are worn and even though it is showing good voltage, the amperage is too low. The brushes are in a holder that comes out of the back of the alternator. You can then unsolder the old brushes and put new ones in.

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Doug

1987 300TD x 3
2005 E320CDI

1984 300d Turbo 141,000
Replace The Alternator Output Low Or Replace The Regulator

Thank you guys the 3000RPM voltage (13.4V) seemed a little low for me too.

I'll buy a new regulator this weekend.
My old unit has the bosch number 1 197 311 003
if i buy the one for diesels (1 197 311 090) will it give slightly more volts. Winter is ahead so I will be happy if will be able to use all my electric appliances such as blower defroster high beams wipers etc. at the same time
or i need to replace the whole alternator to make things brighter (owners manual says it's a 55 amp unit and battery is 74Ah type)

Any opinions?

You need to check your GROUNDS on the car. Remove the ground cable that runs from the battery to the chassis and clean it. Check the engine to chassis ground strap. Chech the POSITIVE lead that feeds the cabin.

You should see more like 13.75 volts @3000rpm

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

Voltage regulator changed ($20) ,Problem solved.

14,00 V idle
13,60 V full load (mainbeams+heater+stereo+rear defroster)
no more dimming lights!

thanks to all who responded.