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Hello Gang,

Having a unique issue that require your help to resolved.

Car : 2006 CLK500 Conv.

3 weeks ago all of the sudden got a Red Battery Warr. sign on dashboard. Did the diag. on voltage from Alternator and found the alternator was not working. Removed it took it to local autozone and it was dead. Replaced it with rebuild unit acquired from dealer. Once replaced everything was back to normal.

Drove car for a 10 days approx 500 to 600 miles and the same issue occurred. Diag. alternator and it was dead so replaced it with another rebuild unit which was tested completely prior to installing it. Everything was checked out. Once replaced everything was back to normal.

Few days back while driving in NY City got the same Red light and car wouldn't start. AAA was called and they jumped the car. once running checked the voltage on dashboard it was 12.6 to 12.3 indicating the alternator is no good. Towed the car back to NJ.

Yesterday, inspected the car engine area in detailed and notice there is a small leak of oil, from left side of engine from back side of head gasket. Positive battery cable which runs from top of the back portion of the engine and down below connection to starter and alternator, the cable has protective sleeve and i found it is covered with Dripping oil. There is a possibility that hot oil may have penetrated within the sleeve and made a contact with positive cable harness. ( Have to work on to remove the cable and inspect that next).

Meanwhile today i have changed the new head gasket and there is no more oil leaking from engine compartment.

Before I invest in new alternator wanted to see if you all expert has any theory that can explain why my alternator is keep getting fried. Is there any other possibility out there that can explain the issue related to alternator ? One more thing i noticed is when the alternator goes bad the voltage regulator from the the bad alternator is working fine when it is swap with
another working alternator.

There are no other codes or issue with the car. each time when I replaced the alternator (2 times already in 3 weeks) after the replacement all test is been performed and everything is working fine.

Any help from all of experts out there is appreciated.

Thanks

Dax
 

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Hello Gang,

Towed the car back to NJ.

Yesterday, inspected the car engine area in detailed and notice there is a small leak of oil, from left side of engine from back side of head gasket.
There are no other codes or issue with the car. each time when I replaced the alternator (2 times already in 3 weeks) after the replacement all test is been performed and everything is working fine.

Any help from all of experts out there is appreciated.

Thanks

Dax
Small world Dax I have a sister in Bloomfield, I was raised in Bayonne.


For the most part oil should be nonconductive, why it is used in electrical equipment. But if enough foreign particles such as carbon or metal particles are present it can become conductive. Use a spray electrical contact cleaner put some cardboard down and clean off the oil soaked wire.

Just to clarify you changed the head gasket or was it the valve cover gasket? The first more likely to leak anti freeze, the later oil. Also you made it sound like it was quick and no big thing which would be a valve cover gasket while a head gasket is a major undertaking.


But I have had bad rebuilt alternators. My daughters mazda, old alt was bad, putting out 8 volts. Replaced it, a week later the new was putting out 18volts, weird things were happening. So replaced it. no problem since. It was the regulator, but it and the alt were all in one.


Is yours in 2 parts? In other words a separate alt and replaceable regulator? If so you may need to change the regulator. I ask because you state the bad alt has a good regulator.

Of course check all connections clean the battery collections. I have heard of batteries shorting out internally, though rare.
 

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Small world Dax I have a sister in Bloomfield, I was raised in Bayonne.


For the most part oil should be nonconductive, why it is used in electrical equipment. But if enough foreign particles such as carbon or metal particles are present it can become conductive. Use a spray electrical contact cleaner put some cardboard down and clean off the oil soaked wire.

Just to clarify you changed the head gasket or was it the valve cover gasket? The first more likely to leak anti freeze, the later oil. Also you made it sound like it was quick and no big thing which would be a valve cover gasket while a head gasket is a major undertaking.


But I have had bad rebuilt alternators. My daughters mazda, old alt was bad, putting out 8 volts. Replaced it, a week later the new was putting out 18volts, weird things were happening. So replaced it. no problem since. It was the regulator, but it and the alt were all in one.


Is yours in 2 parts? In other words a separate alt and replaceable regulator? If so you may need to change the regulator. I ask because you state the bad alt has a good regulator.

Of course check all connections clean the battery collections. I have heard of batteries shorting out internally, though rare.
Thanks wallyo,

Indeed its a small world. I replaced the valve cover gasket which was leaking. I get your point about the faulty alternator. Both instance when the alternator failed the voltage regulator is working fine its the alternator itself is burring out.

I can clean the cable and its outside hosing as suggested but i have feeling it may be damaged due to oil and heat from engine combination. i have ordered the new cable due to arrived in few days. I am planning to replace it with new one and at the time inspect the old one to see if there is any issue. As i have lost two alternator to the same issue i want to find a cause of issue before inventing in new alternator as i suspect it will also get burned out.

See attached image i am replacing the # 5 item on the image which is a Positive cable.

I appreciate your reply and your suggestions.
 

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For my two cents, I think you have received two defective alternators. Unless it can be proved that your vehicle caused the fault I would ask for a refund for both rebuilt's and find another rebuilder. I owned a shop for may years and every so often got defective rebuilt alternators. Did you ever run a load test on the positive wire from the battery and starter? Are you sure your battery is good?
 

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For my two cents, I think you have received two defective alternators. Unless it can be proved that your vehicle caused the fault I would ask for a refund for both rebuilt's and find another rebuilder. I owned a shop for may years and every so often got defective rebuilt alternators. Did you ever run a load test on the positive wire from the battery and starter? Are you sure your battery is good?
Gorj,

Thanks for your expertise, In such case experience is what sometime resolve the issue. The first one from dealer which i purchased last year never got to install it in car until few months ago so i can't return it. Second one i got it online and they only had 30 days return on electrical parts. I am going to get a next one brand new so i know the issue and will have a year warr.

You did bring up a good point about running a load test on the positive wire from the battery and starter, i am not car guys so if you can explain to me how to do that i have multi-meter and i can do what you requesting to do. I would like to share this what i have noticed yesterday.

I have a heavy duty jump box which is fairly new and it holds the power for long time and jump multipal times with full charge everyone i know borrow it from me when needed. Yesterday, when i needed to move the car on side of the house i plugged in the jump box to car battery terminal not the jump terminals, car started right away but i noticed within seconds my jump box from 100% ended up to 40 % which is very odd. May be there is a electrical issue somewhere or ground issue.

I thank you for your reply in advance,

Dax
 

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Gorj,

Thanks for your expertise, In such case experience is what sometime resolve the issue. The first one from dealer which i purchased last year never got to install it in car until few months ago so i can't return it. Second one i got it online and they only had 30 days return on electrical parts. I am going to get a next one brand new so i know the issue and will have a year warr.

You did bring up a good point about running a load test on the positive wire from the battery and starter, i am not car guys so if you can explain to me how to do that i have multi-meter and i can do what you requesting to do. I would like to share this what i have noticed yesterday.

I have a heavy duty jump box which is fairly new and it holds the power for long time and jump multipal times with full charge everyone i know borrow it from me when needed. Yesterday, when i needed to move the car on side of the house i plugged in the jump box to car battery terminal not the jump terminals, car started right away but i noticed within seconds my jump box from 100% ended up to 40 % which is very odd. May be there is a electrical issue somewhere or ground issue.

I thank you for your reply in advance,

Dax
It sounds like your battery has an internal short since your jump box lost power so quickly. If that is not the case then your positive wire is going to ground. You can check that by removing the positive cable from the battery, then attach your jump box negative to the battery negative, now touch the jump box plus cable to the disconnected positive cable; there should be no SPARKS. If there are sparks than your positive cable is going to ground somewhere. Good luck!
 

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It sounds like your battery has an internal short since your jump box lost power so quickly. If that is not the case then your positive wire is going to ground. You can check that by removing the positive cable from the battery, then attach your jump box negative to the battery negative, now touch the jump box plus cable to the disconnected positive cable; there should be no SPARKS. If there are sparks than your positive cable is going to ground somewhere. Good luck!
Gorj,

As per your comments, I just picked up from a dealer a Brand new OEM Battery. Will plug that in today and complete the test as you suggested. Do I have to configure new battery in system using Star ? or it is not needed for this model. I am sure one of the experts on board will know that for sure.

Thanks

Dax
 

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Gorj,

See below updates.

1) Install the new positive cable today which connects to starter and Alternator.
2) Install new OEM Battery and just connected the negative (ground) wire.
3) Connected jump-box negative to batt. negative, and then connected the jump-box Red (positive) to loose newly installed positive cable. and it does sparks.
4) Inspect all the cable around the engine bay area on top and on bottom including the connector. Didn't see any issue or cut or cables grounding to body anyplace.
5) Battery Positive cable also splits and connects to distribution box where you can jump the battery, there are 5 cables are connected from bottom. when touched with jump-box positive terminal they all sparks.

Any suggestion on isolating the grounding issue ?

This is turning out to be major issue.

Thanks

Dax
 

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OK, There will be a slight spark because at the starter connection there is also the connection that powers the vehicle, so there may be some very slight energy draw, like the memory for the radio. What I am referring to is a really large spark, similar to a welding arc.

If it is a large spark, try this: disconnect the cable at the alternator and see what happens when you connect the cable to the positive on your battery. Then remove the other cables from the starter lug, except the cable to the battery and try again. You should have no spark at all because everything is now disconnected except the battery + cable. If you have a spark, then there is a grounding issue in your starter, possibly a defective starter solenoid.
Good luck.
 

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Gorj,

Sorry for the delay in replying, needed access to a lift in order to work on your subjugation of task. I have done following.

1) Remove the connection on Alternator side and had Negative connected to battery and then Black Jumper cable was connected to negative, removed the positive from battery. Touched the red from jumper cable and large spark was there.
2) Remove the connection on alternator and starter and did the same and same spark was there its not just a little spark its a strong one.


3) The positive battery cable has a split which connected to a box which is a positive jump terminal to car. I removed that connection and then connect back the cables to Starter and then alternator and repeat the same exercise and there is no spark.

On that Positive jump terminal box 4 different red cables are connected on bottom, makes it difficult to locate where the short is.

Also car has Brand new OEM battery and brand new OEM alternator installed. Car runs fine no codes on computer no lights. But i suspect it is matter of time when alternator goes. May be few week at the most.

Thanks

Dax
 

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This is good, you have eliminated everything under the hood - Starter and alternator. With the ignition off there should be no big spark at the battery charge terminal. I would pull the cover off the box under the terminal and eliminate one by one the circuit that is drawing so much current. There is obviously a short in one of those circuits.
 

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3) The positive battery cable has a split which connected to a box which is a positive jump terminal to car. I removed that connection and then connect back the cables to Starter and then alternator and repeat the same exercise and there is no spark.

On that Positive jump terminal box 4 different red cables are connected on bottom, makes it difficult to locate where the short is.
I suspect that the box you are referring to is the Prefuse box (F32), located in the engine bay, which has very high-rated fuses that distribute +12v dc to all the other consumers on the car. You could start by removing the fuses one after another to focus on the problem.

For details on F32, (location/circuit) see the thread 'All fuse/relay box details for W209', which is saved in the Sticky Maintenance part of the 209 forum.
 

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I suspect that the box you are referring to is the Prefuse box (F32), located in the engine bay, which has very high-rated fuses that distribute +12v dc to all the other consumers on the car. You could start by removing the fuses one after another to focus on the problem.

For details on F32, (location/circuit) see the thread 'All fuse/relay box details for W209', which is saved in the Sticky Maintenance part of the 209 forum.
Keyhole,

Thank You for your reply. Knowing your background i am happy that you are offering to help. I will try to do what you have suggested tomorrow in daylight. And will try to locate the issue. Meanwhile i have done the following today which i just posted on gorj's reply.

I disconnected the ground wire from battery terminal, then took a test light and touch one side of it to battery terminal and test light probe to the removed ground wire and the test light lights up confirming there is a power draw some somewhere in the car. Now i have to check one circuit at the time by removing each fuse and see when the lights go off tomorrow. And if i find a circuit that is effecting the issue i can then concentrate on that. That is my plan, let me know if I am on right path or not.

Thanks

Dax
 
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