Flickering Electrics

Bad diode in the alternator?

John

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Thanks John Do you know if this can be repalced or is it the whole alternator or nothing.

In the good-old-days individual diodes could be replaced. I really don't know if that's possible or practical with the Benz alternator. I'm sure someone here will have the answer. Tiger?

John

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Flickering seems like the voltage regulator. All the Mercedes I have dealt with (84 190D, 87 300SDL, 89 300TE, 96 C280, all US spec.) have replaceable voltage regulator (and brushes) at the back of the alternator. Some can even be replaced while the alternator is on the engine (though more difficult and you must be familiar with the procedure).

The modern alternators rarely goes bad. There is almost nothing to break, except for the regulator and bearings.

The shop will replace the whole alternator because it is a sure fix. No shop would like to see customer coming back for the same problem. It ruins the reputation. Replacing just the regulator is much less parts ($40 vs $200-$300) but slightly more labor (since the alternator still needs to come out).

How old is the battery? A good battery is like a reservoir and will smooth out the flickering. If the battery is more than 5-6 years old, it is about time to replace. A diesel engine needs more juice to start (than a gas engine).

SammyH wrote:

Thanks Guys

Ill loook further The battery is 3 months old but I suppose is feasible that it could be faulty (?)

Was it flickering prior to replacing the battery? It's possible the battery is the problem, but that would be low on my list. More likely would be the alternator or that there is a loose connection or partial short somewhere. Do they flicker when the car is not started up? That would indicate it's NOT the alternator. Do they flicker only when moving? That would indicate something loose. Also, since you had the battery changed, I presume you've checked the cable connections to make sure they are fastened tight?

A competent shop should be able to diagnose this and tell you with a high confidence level if it is or isn't the alternator. Also, 500 pounds plus labor sounds very high for an alternator. Here in the states aftermarket alternators are available for similar MB for $200

Thanks for all your help guys. If you ever need any help on the things Im good at - just give me a shout.

Was it flickering prior to replacing the battery? It's possible the battery is the problem, but that would be low on my list. More likely would be the alternator or that there is a loose connection or partial short somewhere. Do they flicker when the car is not started up? That would indicate it's NOT the alternator. Do they flicker only when moving? That would indicate something loose. Also, since you had the battery changed, I presume you've checked the cable connections to make sure they are fastened tight?

A competent shop should be able to diagnose this and tell you with a high confidence level if it is or isn't the alternator. Also, 500 pounds plus labor sounds very high for an alternator. Here in the states aftermarket alternators are available for similar MB for $200

Which is/are?....

DAS

To reply directly replace 'nospam' with 'schmetterling'

DAS