"Alternator" 115 Amp Bosch AL129X works in 123s! - Page 17 - PeachParts Mercedes-Benz Forum

maurinquina · #**241** 10-31-2012, 02:29 PM

I'm trying to do the alternator upgrade on my 1991 420 SEL. I recently installed euro headlights and extra 2 bulb sockets in the brake light lens. I found a rebuilt
150 Amp alternator but I have a hard time sourcing the correct upgrade wiring. I removed the existing wiring and it's not copper strand. All the wiring I can find at Pep Boys. Auto Zone is copper strand. I don't want to use copper because of the dissimilar metal corrosion which will develop sooner than later. Even the junction block doesn't have any copper parts in it. Since I've never seen any corrosion on the battery post in any of the MB's I've owned, I would like to stick to using the same type of cable as oem. Can someone shed some light on this newly developed snag ? I did search the forum up and down but no one touched on this subject yet. Thanks

JamesDean · #**242** 10-31-2012, 02:33 PM

I used copper wires in my alternator upgrades on my 190E. Nice big 0 gauge copper wire I sourced online.

I find it surprising that MB did not use copper in the other wires. I had always though they did.

maurinquina · #**243** 10-31-2012, 02:50 PM

ever develop any corrosion ?

JamesDean · #**244** 10-31-2012, 02:58 PM

not that I am aware of. My distribution block is factory too. It looks copper to me. I did spray the terminals with some of that battery terminal protection stuff.

I would use quality copper lines.

maurinquina · #**245** 10-31-2012, 03:17 PM

a shot with copper. I will probably run new wires to the starter as well. It can only do good. Thanks, James.

maurinquina · #**246** 10-31-2012, 03:23 PM

to get the Becker Grand Prix 1432 illumination bulbs ? I sent an e-mail to Ed at Becker and he replied saying that it must've been an old post. All he can do now is repair the faceplate for $90 plus shipping ( repair meaning change 6 bulbs). I finally got the receiver and CD changer working but the faceplate is a real eyesore especially at night.

JamesDean · #**247** 10-31-2012, 03:27 PM

I've since tossed all my old Beckers, I've got newer Pioneers and Kenwoods in place. Perhaps someone else on here could chime in.

maurinquina · #**248** 10-31-2012, 03:33 PM

wiring advice. I will keep you posted on the progress on my W126.

gsxr · #**249** 10-31-2012, 04:03 PM

I believe all the MB wiring is copper. However it may be coated copper conductors, making them appear silver externally. There should be no issue mixing plain copper wire. I've never had an issue.

maurinquina · #**250** 10-31-2012, 07:56 PM

write-up with pictures a few days ago and decided to follow through with your directions. I seem to have everything together except the lugs and ring terminals. I was checking online and have problems determining what size they should be. Example: for the 4 gauge wire they have numerous sizes of lugs and the same goes for the 16 ga ring terminals. Could you help out and tell me the size I should be looking for ? Also, is it correct that with the higher output alternator you would take up both spaces in the junction block instead of just one ? One wire connecting inline to the starter and the other to the battery. the 16 ga goes on the top with philips screw. Would that be correct ? I have a 1991 420 SEL. Thanks

gsxr · #**251** 11-01-2012, 08:23 AM

Yikes... it's been many years since I did this upgrade. I can't remember the exact sizes required.

The best thing would be to measure the diameter of the posts on the alternator (and/or the distribution block on your car) and get ring terminals which have a slightly larger ID.

For the junction block, it depends on the setup for your particular chassis; as some chassis use different junction blocks. I've never owned a W126 so I'm not sure what those are like. I assume you have seen the "4ga" cable photos on my website in this directory? There are some good photos of the W124 setup, maybe see if the W126 is similar?

maurinquina · #**252** 11-01-2012, 10:25 AM

the same as on yours with 2 posts. I'm sure the arrangement for connecting wires would be the same on a W126. I did take pictures before taking off the wiring but since the wires had 10 inches of MB black heat shrink on them I wasn't able to see which came up from the starter and which came up from the alternator. To make matters worse both wires have the same reddish cloth material on them. I think the starter cable and battery cable go on one post since the starter draws from the battery on start-up. The alternator cable goes by itself on the other post since it charges the battery after the car is running. I hope I just didn't spell out a recipe for a 116 BQ ..... it's not even the weekend yet.

Here is the answer for anyone facing the same issue. Took these pictures at the junkyard of a 1988 560SEL. It's exactly the same arrangement as on my 1991 420SEL Blk/Blk (The Diplomat).

maurinquina · #**253** 11-08-2012, 07:09 PM

Quote:

Originally Posted by JamesDean

I used copper wires in my alternator upgrades on my 190E. Nice big 0 gauge copper wire I sourced online.

I find it surprising that MB did not use copper in the other wires. I had always though they did.

The 0 gauge copper wire came in today plus the lugs. This wire is THICK ! I think it's thicker than the battery connections. You can hardly bend it. This is a serious wire. The delivery just came and it's dark outside so I can't check it on the car but can you tell me if that's what you used ? I hope I didn't get the sizing wrong when I ordered it. It said 1/0 gauge. Is that correct ? I have attached 2 pictures.

JamesDean · #**254** 11-08-2012, 11:27 PM

Quote:

Originally Posted by maurinquina

The 0 gauge copper wire came in today plus the lugs. This wire is THICK ! I think it's thicker than the battery connections. You can hardly bend it. This is a serious wire. The delivery just came and it's dark outside so I can't check it on the car but can you tell me if that's what you used ? I hope I didn't get the sizing wrong when I ordered it. It said 1/0 gauge. Is that correct ? I have attached 2 pictures.

Looks right to me!

maurinquina · #**255** 11-09-2012, 09:35 AM

Quote:

Originally Posted by JamesDean

Looks right to me!

150 amp alternator should come in today. Thanks for helping out.