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  #31  
Old 11-06-2007, 10:17 PM
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I second bullitproof's comment about the terminal block on the right fender. I have seen the connections there look great and be basically insulators. The black corrision gets to the connectors. Just unscrew the connections (one at a time) and make them shine again. I was pulling my hair out one time until I actually got out my meter and started checking voltages directly from the alternator.
Other thing I have found. When you get large temperature swings in a day (like in spring and fall). The battery terminals seem to get bad connections. They shoud shine too.

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  #32  
Old 11-06-2007, 10:54 PM
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Ok I went out. Here's the results:

Battery sitting with nothing running: 12.6v
Battery after starting car: 11.6v
Car running, lights on: 11.something (can't remember, but a slight drop from the above number)

Raising the rpms seemed to make no difference, and obviously the drop in voltage would suggest that the alternator was doing nothing at all to add any voltage into the stream...

BUT THEN

Out of nowhere with the engine running (I didn't touch anything directly preceding this, was just looking at the meter), the voltage jumped up two volts, and was reading upwards of 15v + when I revved high enough, as if the alternator just suddenly kicked in and was supplying electricity again.

Battery terminals are brand new and the clamps are shiny.

No bad ground terminals as far as I can tell (though I will check the terminal block in a second).

I don't have time at the moment to get at the fan, so I couldn't do that part, but what does this all suggest to you?

*Edit: P.S. Is the alternator connected directly to the battery, or what is the wiring path from the alt to the battery, ie: does it stop off anywhere inbetween, so I can check that.

*Edit edit: I went out and looked at the terminal box (which it seems is where the alternator connects to before going to the battery), and there is probably about 25 years worth of dirt and dead spiders on them. It is too late to clean them off or do anything else now, but I suspect that is a starting point.
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1979 240D w/4 Speed Manual, Light Blue Estimated 225-275K Miles - "Lil' Chugs"
Sold but fondly remembered: 1981 300TD Turbo Tan 235K miles, 1983 300SD Astral Silver 224K miles


Last edited by chetwesley; 11-06-2007 at 11:06 PM.
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  #33  
Old 11-07-2007, 09:57 AM
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Last I knew, when I shut down the car, the alternator seemed to be doing at least something. This morning when I started up, I tested with the volt meter again, and again it was back to nothing, no fluctuation on the voltage, just a straight reading which didn't change with increase in RPM. Is there anything that would make an alternator not work when the car first starts, or is it just a coincidence? I didn't get a chance to check again after that, as I was running late.
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  #34  
Old 11-07-2007, 10:12 AM
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Change the voltage regulator on the back of the alternator. See if that cures the problem..........if not, you'll need to replace the alternator.
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  #35  
Old 11-30-2007, 05:04 PM
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Update:
I changed out the VR, but nothing.

However, someone brought up in another thread that if your battery light is not coming on, that the alternator is not going to get "excited", and will not start producing electricity.

My battery light is not coming on before I start the car.

What are the possible causes of a lack of battery light?

So far, what I have picked up is:
1) that the light itself is dead

or

2) that a wire from the alternator (or somewhere in the circuit to the light) is not making a connection.

Are there any other causes of a lack of battery light?

It very well could be a coincidence, but this whole problem started at about the time I was trying to get my tach amp to work, and I wonder if I could have bumped something electrical that messed my 25 year old decaying electrical system up... but that seems unlikely to me.

Any further ideas are much appreciated.
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1979 240D w/4 Speed Manual, Light Blue Estimated 225-275K Miles - "Lil' Chugs"
Sold but fondly remembered: 1981 300TD Turbo Tan 235K miles, 1983 300SD Astral Silver 224K miles

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  #36  
Old 12-02-2007, 06:41 PM
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bumpity bump bump
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  #37  
Old 12-02-2007, 07:01 PM
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check the main wire attached at the back of the alternator for looseness. The no-batt-light when switched ON happened to me before. The terminal at the alternator end was loose. Had it removed and checked for breakage in the wiring. True enough the wires inside the terminal housing was frayed. Had it rewired and voila... happy charging...

BEFORE:
engine not started - 12.2-12.4V
engine at idle - 12.9V-13.0V (sometimes drops to 12.4V), when the terminal wire at the back of the alternator is "moved" from side to side, the V reading changes from 12.4 - 13.0
engine revved - 13.1-13.2V
engine with all electrical load (AC, headlights, foglights, aux fan, radio) - batt lights turn on with a dim light - 12.2V [when revved, dim batt light goes out, 12.9V]

Then it happend.. no batt lights... when switched on. So rewired, placed back..
AFTER
engine not started - 12.4V (i think i have to replaced this as i have gone around for more than 6 months with the on and off problem with charging that it may have done some damage to my batt)
engine at idle - 13.5V (BIG DIFFERENCE!)
engine with full load - 12.7V, no dim batt light. when revved, back to 13.5V
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1975 200 - Sold (no pix);
1978 200 - Sold - http://www.pbase.com/hboy/redbaron
1979 300TD - Sold
http://www.pbase.com/hboy/greenwagon
http://www.geocities.com/hboy726/300TD.html
1985 230E - now my daily driver...
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  #38  
Old 12-02-2007, 07:15 PM
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Thanks Mike. I actually was just checking my alternator plug... I don't think it was loose (and I have actually checked that before) and the terminals look ok on the back of the plug with it open...

BUT

I was checking the plug with an ohm meter to see if/where the plug slots connect with the terminal box on the fender, and I noticed that two of the slots on the alternator plug have zero resistance to one terminal (the frontmost one) the terminal box. When I tested right at the slots on the plug, the two large slots on the plug have zero ohms of resistance to eachother... that doesn't make sense to me (ie: why have two slots on a plug with seperate wires if they go to the same place?) but suffice to say I know next to nothing about how the charging system works, so feel free anyone to enlighten me.

The gist of my question: Is that how the plug is supposed to be, are the two big slots on the alternator plug supposed to be connected to eachother?

Super Thanks
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1979 240D w/4 Speed Manual, Light Blue Estimated 225-275K Miles - "Lil' Chugs"
Sold but fondly remembered: 1981 300TD Turbo Tan 235K miles, 1983 300SD Astral Silver 224K miles

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  #39  
Old 12-02-2007, 11:12 PM
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Quote:
Originally Posted by chetwesley View Post
Thanks Mike. I actually was just checking my alternator plug... I don't think it was loose (and I have actually checked that before) and the terminals look ok on the back of the plug with it open...

BUT

I was checking the plug with an ohm meter to see if/where the plug slots connect with the terminal box on the fender, and I noticed that two of the slots on the alternator plug have zero resistance to one terminal (the frontmost one) the terminal box. When I tested right at the slots on the plug, the two large slots on the plug have zero ohms of resistance to eachother... that doesn't make sense to me (ie: why have two slots on a plug with seperate wires if they go to the same place?) but suffice to say I know next to nothing about how the charging system works, so feel free anyone to enlighten me.

The gist of my question: Is that how the plug is supposed to be, are the two big slots on the alternator plug supposed to be connected to eachother?

Super Thanks
Remove the alternator from the vehicle and take it to a competent shop for testing. My money is on a bad alternator. A new VR doesn't always cure the alternator problem.
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  #40  
Old 12-03-2007, 04:44 AM
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on the few alternator terminals i've seen, there are three spade plugs, two big ones and 1 small plug. The two big plugs evidently join together down the line...dunno if that's right though, but that's so far how the wiring in the car's ive seen opened.
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----------------------------------
1975 200 - Sold (no pix);
1978 200 - Sold - http://www.pbase.com/hboy/redbaron
1979 300TD - Sold
http://www.pbase.com/hboy/greenwagon
http://www.geocities.com/hboy726/300TD.html
1985 230E - now my daily driver...
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  #41  
Old 12-03-2007, 07:00 AM
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Quote:
Originally Posted by chetwesley View Post
Update:
I changed out the VR, but nothing.

However, someone brought up in another thread that if your battery light is not coming on, that the alternator is not going to get "excited", and will not start producing electricity.

My battery light is not coming on before I start the car.

What are the possible causes of a lack of battery light?

So far, what I have picked up is:
1) that the light itself is dead

or

2) that a wire from the alternator (or somewhere in the circuit to the light) is not making a connection.

Are there any other causes of a lack of battery light?

It very well could be a coincidence, but this whole problem started at about the time I was trying to get my tach amp to work, and I wonder if I could have bumped something electrical that messed my 25 year old decaying electrical system up... but that seems unlikely to me.

Any further ideas are much appreciated.
my thread is the one to which I believe you are referring
I finally put my charging system demons to rest and wrote a short troubleshoot here
Altenator plug
I believe it is your alternator, take it out and back to the place you bought it, most of them come with some kind of warranty, also make sure you get them to test the new one when it comes in to assure that your new part is going to work. these things are remans, mostly done in India now days, it isn't unheard of for one to come in and not work on the spot.
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  #42  
Old 12-03-2007, 03:22 PM
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Electrical weirdness (long, sorry)

I have mentioned that I am having problems with my alternator. It seemed to work intermittently for a while but now seems to be doing nothing...

I am wondering if these problems were caused initially by some other strange issues with the electric in my car. I will first describe what is up with the electrical in my car, and then ask my questions.

First of all, the PO of my car began work on some kind of VEG oil system which involved adding and routing some wires around from under the hood into the cab (for a switch to either a fuel heater or a tank valve), but as far as I can tell, he didn't ever actually make any significant alterations to the electrical system.

Next, I have had problems with my blower motor. The brushes are worn down. I wedged something into it (a small woodchip to give to get it to temporarily make contact again until I could replace it or get new brushes. After doing that, it worked for a short time, but then stopped. I just assumed it stopped because my "fix" fell out or something, and I haven't had a chance to open it up again and check what was up with it. The blower did not work when I bought the car (because of the brushes).

HOWEVER, last night I looked in my fuse box, and the fuse for my blower was totally melted. I replaced the fuse and the blower works again, kind of (there might be other issues with the CC system).

Now, what I notice now that the fuse is replaced is that whenever I turn my blower on, the otherwise dead tach reads a constant reading of about 2000rpm (not that it matters what the reading is exactly), and when I use the electronic seat control, it jumps up even higher, maybe even pegging the needle.

Other than that, the electrical seems to be working fine for other things (headlights, interior lights, windows, etc).

Now that you have the background, the reason I bring this all up is that my problems with my alternator began around the time that I did a few minor things involving the electrical in my car.

I did the following minor electrical things around the time that my alternator stopped working consistently:

1. My "fix" on my blower motor as mentioned above. Because of the melted fuse, I am very suspicious of this one.

2. I tried to do the tach amp cigarette butt fix, but couldn't get the cap to pop off of the top part of the amp (I got the cap unscrewed, but couldn't get the plug part to come out of the cap in order to get the butt in there). The only reason I include this is that one of the wires that the PO installed connects to the ground on the tach amp.

3. I had a dim headlight, which was cured by wiggling the connections behind the housing.

I am going to have my alt tested and replace it if it turns out to not be working (which I am 95% sure it is not), but what I am wondering is if there is anything in this that could have actually fried the alternator.
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1979 240D w/4 Speed Manual, Light Blue Estimated 225-275K Miles - "Lil' Chugs"
Sold but fondly remembered: 1981 300TD Turbo Tan 235K miles, 1983 300SD Astral Silver 224K miles


Last edited by Brian Carlton; 12-03-2007 at 06:20 PM.
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  #43  
Old 12-03-2007, 03:27 PM
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Would the dead alt cause the battery light to not come on?
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1979 240D w/4 Speed Manual, Light Blue Estimated 225-275K Miles - "Lil' Chugs"
Sold but fondly remembered: 1981 300TD Turbo Tan 235K miles, 1983 300SD Astral Silver 224K miles

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  #44  
Old 12-03-2007, 05:27 PM
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Your coming behind a hack job, good luck.
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  #45  
Old 12-03-2007, 05:44 PM
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It is only a very minor hack job. It is a couple of wires routed from the hood to the cab, which as far as I can tell, do not form any kind of complete circuit.

It would be helpful to know if anything I have noted (such as the tach shooting up in response to using electrical devices) is something those with non-hacked cars have ever noticed.

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Sold but fondly remembered: 1981 300TD Turbo Tan 235K miles, 1983 300SD Astral Silver 224K miles

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