I haven't posted here in a while but I sure hope you guys can help me out.

I did search and came up with some useful information but I would still like to get a general show of approval before I spend money that I don't really need to.

My charge light came on in my 190D (84 2.2) this evening. I went to have the battery and alternator tested at the local Advanced Auto AND Autozone (only ones open at this hour) and sure enough my alternator is not charging. I am not an automotive electrician but I think they said it was putting out 12.3 volts and something about 1.6 amps. I dunno. Anyway, I read how the voltage regulators sometimes could go out before the alternator really needs to be replaced and I wanted to see if maybe I should try that first or is it worth the hassle? I can put the part in but when someone starts throwing out voltages and amps I just look at'em with a blank stare. Kinda at someone else's mercy when it comes to that stuff.

The light went out for a brief while going up the road but came back on a while later. The light does get dimmer as the rpms increase but it doesn't go out.

Kevin

Can ya hepp me?

I would say the greatest probably issue is that the alternator is no longer charging. When you start to see that battery light at all - its not particularly good news (at least as far as the charging system is concerned). And just because the light goes out or gets dimmer does not mean the problem is getting better or going away. I can vouch for that.

Still estimating probabilities - the most likely thing is the brushes on the alternator's voltage regulator assembly. On most of these cars its not too bad to get to and only two screws, and on the order of $20. If that's not the problem (i.e. you have to replace the whole alternator) then keep the brush/regulator part as a spare.

So, if you have the time to deal with it, my suggestion for a start is the brush/regulator assembly.

It would be a clearer diagnosis if you had a voltmeter to look at the battery voltage before and after starting. Typical is 12.5 or so before starting and 13.5-14 after starting when the alternator is charging.

Can be many things, I'm just telling you what I think the odds are for the first thing to try, weighted by 1) Probability it is the actual issue, 2) Cost of the part, and 3) effort to replace the part.

When it happened to me, I had other cars to pull a regulator from as a test. Easy confirmation.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

I really appreciate the help. Now don't fall in the floor laughing at me but I thought maybe if I just changed the regulator that I will not have to remove the alternator, right? There seems to be enough room to work at the rear of the alternator once rear cover is removed. I may be totally wrong on that but it looks that way to me. Once again, any help would be greatly appreciated.

P.S. I usually just dive in an tackle these kind of jobs learning as I go but I really don't have the time to learn on this one. I need to be rather efficient in getting this one completed. I am just way too busy at the church these days.

Kevin

Don't try to fix the alternator with the alternator in the car. It's a 5 minute job to remove it. It will be much more hassle when you eventually have to remove it because you can't get it back together properly anyway. My personal vote is always to take your existing alternator to a local electrical motor/starter shop and have them rebuild your existing unit. This will be the cheapest way to go, and you typically get very good service from these local shops.

My 2 cents.

SteveM.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner

'preciate it!

If you have good access to the screws with a screwdriver, then the voltage regulator/brush assembly is an easy replacement without removing the alternator. With the typical MB placement, you'd do this from underneath the front edge of the car.

Just an opinion.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

have the alternator rebuilt. I checked on the voltage regulator and the local rebuild shop had one in stock for $28. I asked for a price on rebuilding mine and they said $85 to $100. Its a very reputable shop and I thought I would be better off in the long run to have it rebuilt. THanks for your suggestions and helpful advice.


Kevin

There was a very recent thread on alternators, and the consensus was to watch out on rebuilds. Apparently many shops replace only the brushes, and not the bearings and other wear areas unless they are really bad. Many rebuilds fail in a matter of months. I would check Ebay and pick up one of the rebuilt Bosch units there. They can be had cheap (under the $ quoted for a rebuild, in fact). I bought a very clean, recently-rebuilt Bosch unit (with the Bosch rebuild sticker in place) there for $29 recently. Even with shipping it was little more than whata set of replacement burshes would cost.

If you poke around a bit you can find LOTS of info on your problem, much of it very recent. Mine alt. went out a week ago... click on my user name and see what posts I've made recently, which ought to lead you to some of the discussions.

Chris

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)