AATFWIW = And Another Thing...For What It's Worth.

Just something else that I have had a few times now on MB coils failing...nothing to do with battery drain.


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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

What year model car is yours that the ignition coils fail on?

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

124's EZL coils

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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

volt reg screws into back of alternator, held in by 2 screws. look on the fastlane website to see what it looks like new. if your brushes are worn down to a nub, that may be your problem. the 2 brushes should be roughly same length and should protrude quite a bit.

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car

I had a similar problem on a 89 420 SEL. Battery would go dead, sometimes after 2 weeks, sometimes after 1 week, sometimes after 2 days. The final time it died was on the highway, going 100 KPH, with heater on, lights on, radio on, seat heater on (it was -22c outside). When the battery started to die, the cassette player turned off automatically, next the SRS light came on, and then various warning lights came on, then the headlights started to dim.

The problem was the alternator. It was OK when it was ice cold, but after running for some time, it stopped charging. It tested good when I took it in for a test, at Canadian Tire.

I replaced the alternator, I have had no problem since replacement. The voltage at the battery terminals is now 12.8v with the car off. When idling, the voltage at the battery terminals is 14.2V

The alternator that failed was only 1.5 years old. The brushes were in excellent condition, 1/16th inch shorter than brand new. I believe my old blower motor blew the alternator, drawing too much amperage. The shaft was very difficult to turn, compared to the new motor. I do have a clamping amp meter, so I could provide current draws on the 420, if you are interested.

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1989 420 SEL

I gave the car a boost this morning and ran it for a little while. I went to start it again after an hour and it didn't start. I guess I didn't let it run long enough. I took a closer look at the alternator and it looks like it's the original one. I wanted to remove the voltage regulator and look at it closely, but we still have 50mph winds gusting here combined with rain.

Btw I called Canadian Tire and they charge $39.95 for the AVR -amperage voltage resistance test and said that's all they are allowed to do on a Mercedes. Whatever the results after that point, I'm on my own.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

The same problem happened to me last weekend. Both SRS and ABS come on at the same time. The car stop a few miles later. I changed a new battery, and check the voltage, it read 12v with lights and A/C on. today, I removed the voltage regulator, the regulator brushes is one longer than the other (both brushes are shorter than the new one). The new reading is 13.5v when lights and A/C are on.

Jack

I just noticed today that the glove box light was on and the head lights were not even on. I closed th glove box door and noticed that the light stayed on. I removed the bulb. Let's see if that makes a difference.
I was tied up today trying to sort out the alarm issue and I just bought and installed for new Michelin tires and got an alignment.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

Lino, 1990 300ce here. Had same problem 1 year ago. Changed voltage regulator, no difference. Big battery drain measure 0.2A constantly.

Check the charging voltage. For me, it was the alternator itself draining the battery. Replaced it. Problem solved.

How could you determine if the alternator is draining the battery?
Thank you.

I'm going to replace the alternator no matter what. If you may have noticed, I have another thread regarding alternator options.
Alternator Options - I need Help!!
I'm most likely going for the big 150 amp alternator upgrade. It makes no sense to me to go back to the oem 70 amp that is in my car now.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

I was wrong about the glove box light only being on when lights are on, I checked and that is not correct, it is on whenever ignition is on. Sorry if I misled you.

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car

Thanks . I appreciate your help.

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

Yesterday, I had some free time and so I figured I'd take the car to the garage for testing. I gave the car a boost and off I went. I had to wait for a an hour since I didn't have an appointment.

When it was my turn, the car didn't start - it was dead again. I borrowed the charger and hooked it up to my battery and waited for a while. Then I took the car in to the garage to test the alternator. It failed the test, reading under 12v.

So I realized I should buy a new voltage regulator to see if that would make a difference since the alternator rebuild shop, as fortune would have it, moved in across the street and had the regulator in stock.
I bought it and had my mechanic install it and do a re-test. This time the reading was 13.5v which was good considering that the battery was dead just a little while before that.

My mechanic also checked the fuses one by one to see if there was a drainage anywhere and found nothing. We also pulled the 2 fuses from the alarm system. We did this, because I still haven't been able to get it reprogrammed.

This morning I turned the car on with no problems. I didn't go anywhere in it though. I tried the car again this evening and it's still working. Maybe that's all it needed. Anyway, i just ordered a 150 amp alternator that I should receive in a few days. I'm going to remove the 70 amp factory unit when it gets here and so as long as it works for this week, I'll be ok.

Here are some pics of the old voltage regulator:

Attached Thumbnails

 

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1989 300CE Astralsilber/Schwarz
1992 300CE Schwarz/Schwarz

the length of the brushes looks okay to me.
Anyway glad that replacing that solves your problem.
i used to carry a spare one for my car.
Now i m using the spare one on the alternator,i resoldered the old one with new brushes as the spare(cost 2-3 $)

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Tom 2010 C250 4-matic Sport (Canada)

Man lino, your just throwing money at your cars. Maybe you should send me your used parts?

Jorg