alternator/voltage question
 

Hello all,

Need a bit of help from you guys. I have a 1983 240D and recently I have been getting a dimly lit battery/brake light on the left side of the cluster. I figured it probably was the charging system, so I checked the voltage. It seems ok when the light is not on (12 volt not running, 13.4+ running)...but when the lights are dim, I'm getting 12 volt on a running car. Anyway, the lights seem to dim only after driving the car for a while. If the car sits, then the light will not come on for a while unitl I have been driving the car for a bit.

Secondly, I saw a post regarding replacing the voltage regulator and went to check it out on my car and found that I have a little black connection box where the voltage regualtor would probably be. The black box has a 3 wire setup going into it and I played a bit with it and couldn't figure how to fully disconnect and what to do after that. The alternator I currently have says it's 55 amps and not sure why, but it says motorola on it. Any clues on what type of alternator is currently on the car and if there is a voltage regulator that I can change on it?

I think you should have more like 14.4, but maybe thats not a big deal. Anyway there is a wire "bale"/clip thing over the regulator that must be pushed over then unplug the wiring connection and remove the two screws to replace the regulator.

I recommend you look at this set of posts: http://www.peachparts.com/shopforum/diesel-discussion/232806-touchy-w123-voltage-regulator-3-warning-lights-same-time.html
(Touchy W123 Voltage Regulator - 3 Warning Lights on at Same Time.)

You described the set of connectors which lead to the alternator and wire harness not the voltage regulator. (little black box with a cover that lifts up)

The voltage regulator is installed on the back of the alternator. Try the regulator first. It's lots less expensive to get it from Mercedes Shop than from MB dealer and that includes shipping, unless you order > $100 in which case shipping is free.

The voltage regulator looks like a "moth". The diode in the center is the body and the 2 ceramic pieces on either side are the wings. In a 300D turbo (and 240D) it is secured with 2 straight blade small screws which are a real pain to remove (with a turbo) when it's in the car. But, it's possible if you have moderate size hands and some patience. Tip: use a flat blade 1/4" driver bit in a rachet driver to loosen it up. On the screw toward the engine... Put the right hand palm side up under the alternator to hold the driver in position. Then use your left hand to work the rachet. You can use a stubby straight blade screw driver to remove the one screw closer to you. (On a 240D you probably will have direct access because on the 617 engine with a turbo there isn't a whole lot of room) When you put the new regulator in you have to sort of wiggle and swear it into position. Start one screw with your fingers and then swing the other side up and start the other screw.

The other problem is that your alternator might be toast. Get yourself a good used one from another 123 if you can. Check the voltage with the new regulator in place before you go after this bear. (It should be in the 14.4 volt range.) It can be tricky to remove the adjustment bolt without bending the heck out of it or breaking it. (done that been there)

The comment about the bale clip is that it is incorrect. Instead the clip covers the harness connector that goes into the alternator and NOT the voltage regulator.

Er, is there something unusual about these Mercedes? Why is it not the standard 13.8V under load? Or is that with no load (though I didn't think it should fluctuate that much)?

Did the Regulator that is on the car say Motorola or is Motorola some where on the Alternator itself?
Any chance of posting a picture of the back of your alternator?

if only the Regulator has Motorola on it is possible that Motorola makes Voltage Regulators that fit Bosch Alternators
My Volvo came with a SMV Alternator and I replaced it with a Delco Alternator from the Junk Yard. It may be possible that a prior owner put a Motorola Alternator on the car.

It says Motorola on the alternator itself. There is a ID badge thingy that lists the part #...it gives no mention of mercedes on the alternator. Maybe that's why I can't find the voltage regulator.

The older (that uses a separate regulator; a ½ inch thick rectangular brass colored box with I believe it was 3 wires) Motorola Alternators have a square access area in the rear where you can pull out the whole assembly that holds the burses.
My memory is kind of vague on this but I believe on the newer ones they used that same square area and similar to the Bosch Alternator now have the Voltage Regulator/Brush Assembly as one unit.
Motorola alternators of the 55 amp size are not common on Cars but are seen on industrial equipment like Forklifts and there Carrier Refer Generator Units where I worked had them. So there is a lot of them out there.
But for parts such as the Voltage Regulator I believe you will need to go to NAPA or someplace similar. They may be able to access that part number that is on the alternator.
See if this one on Ebay resembles the one you have. You can see a little bit of the Voltage Regulator on the back in the pic; also see if the part number they give is similar.
Also you may only need to change the Brushes that may be worn out.

http://cgi.ebay.com/ebaymotors/Atomic-4-heavy-duty-Motorola-Alternator-55-Amp_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c39Q3a1Q7c66Q3a2Q7c65Q3a12Q7c240Q3a1318QQ_trksidZp3286Q2e c0Q2em14QQhashZitem190258565457QQitemZ190258565457

On Ebay there are some Pics of Motorola regulators:
http://shop.ebay.com/items/_W0QQ_nkwZmotorolaQ20voltageQ20regulatorQQ_armrsZ1QQ_fromZQQ_mdoZ

Thanks so much diesel911. I'mma take another look at it tomorrow. I'm thinking of just changing the alternator altogether instead of trying to locate long lost parts for it. I could swear that it had nothing that resembled a voltage regulator, but I will take a look at it again.

Depending on how much time you have to get your car running you might want to take the old Alternator to a Parts Place and have them see if they can identify it. Also, have them test it to see if it works while you are there.
It looks like in the past some Jeeps and AMC cars used Motoroa Alternators. Also, I my