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Discussion Starter #1 (Edited)
I've read few posts lately with alternators as subjects so since I just replaced mine I wanted to give some inputs:

For probably almost a year I've been having strange issues where most of time the difference between battery only and alternator running voltage was around 0.5V which is way to low as it should be at least 1V +.
I've done some tests including test at Autozone with a fancy digital tool (I forgot the name) and battery and alternator both passed.
I was not impressed with the the test or the testers but let's be honest, you're not typicaly dealing with the top ASE certified mechanics in the auto parts chain stores.
To add more confusion my OBD always voltage reads about 0.5V less than voltage taken with my Craftsman (rebadged Fluke) at the engine bay positive terminal. But, that has nothing to do with the first issue, just wanted to mention as it's odd.
Anyway, since I was replacing tensioner and pulleys already, I went ahead and got the last remanufactured Bosch at Amazon for $280 shipped.
I was debating to get the one at FCP Euro for litlle more and with lifetime warranty but strangely Amazon didn't charge any core which I prefered since I wanted to keep the original for possible later rebuild. Also, bearings on original were getting little noisy so it was aditional reason for replacement.
My good friend Sreten mentioned that much cheaper option was to rebuild it with new bearings and voltage regulator as he did in Germany. He's right of course, but it seems that good quality rebuild parts are harder to get here in the states and the price of reman alt is much cheaper here than in Germany.
I was also surprised that Bosch I got shows being remanufactured in Germany. Just about any remanufatured alternator or starter I've handled over the years was remanufactured here in the states. That's ok with me as I hope Hans did a better job than Billy:

I've read few diy's that differ somewhat but i prefer to unbolt steering pump and move it out the way. Yes, the 17mm nut is tricky but I didn't see a need for a flex ratchet wrench, just a regular one with ratchet function




New one went in relativey easy with 17mm nut being litlle bit stuborn but nothing too hard


As I mentioned in other post, the tensioner with 2 pulleys from M62TU is direct fit to S62 with removal of sliding plate on top


And, success!
It seems that old alternator was the culprit after all. Now I'm getting the difference of 1.2V (12.4 vs 13.6).


I'm aware that difference could / should be even bigger, like 1.5V but there a quite a few factors in play that can affect the fluctuations.
I did charge the battery prior to starting the car and just finished the 30 mile drive and I'm getting 13.7 now.
 

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Discussion Starter #3
I'm curious to know what that Autozone tool is and what it tested for.
My bad, its the Advance Auto Parts. I've just checked the print out I kept. I' m almost certain they used this:
Basicaly, they checked the battery cranking power, alternator charging capabilites etc...
Whatever it is, my running voltage is 0.5V + higher now and that is not coincidence.
 

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I replaced the alternator a couple years ago (first one went 160K miles) and that 17mm positive wire nut was a total PITA but like you said, not the end of the world.

So fast forward to last spring and I'm replacing the entire engine (unrelated, valve issue). When the engine is out you have a choice of taking the wiring harness for the + wire out of the subframe (and it kinda snakes under another underbody panel where you can disconnect it) or leaving it in. Well, by that time I was totally tired of taking stuff apart so Ieft the wire harness in. I'll be damned if yet AGAIN that alternator + wire connection wasn't one of the biggest PITA parts of the entire engine removal and reinstallation. Had to unbolt the alternator (which I had just previously bolted onto the new engine) and pulleys and everything to be be able to tilt the alt back and whatnot. Anyway, for anyone replacing their engine just take that damn wiring harness out with the engine regardless of how tired you are!
 

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Discussion Starter #6
I replaced the alternator a couple years ago (first one went 160K miles) and that 17mm positive wire nut was a total PITA but like you said, not the end of the world.

So fast forward to last spring and I'm replacing the entire engine (unrelated, valve issue). When the engine is out you have a choice of taking the wiring harness for the + wire out of the subframe (and it kinda snakes under another underbody panel where you can disconnect it) or leaving it in. Well, by that time I was totally tired of taking stuff apart so Ieft the wire harness in. I'll be damned if yet AGAIN that alternator + wire connection wasn't one of the biggest PITA parts of the entire engine removal and reinstallation. Had to unbolt the alternator (which I had just previously bolted onto the new engine) and pulleys and everything to be be able to tilt the alt back and whatnot. Anyway, for anyone replacing their engine just take that damn wiring harness out with the engine regardless of how tired you are!
That is good advice. I'll file it under to do list if I ever remove the engine. I'm not planning to but you never know.
 

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Discussion Starter #7

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Sketchy how often we are seeing pretty new Bosch rebuilds fail in these cars. UG. At least if it happens again, I can cry and whine all I want about that 17mm nut, but at least the alternator will be Free from FCP!
 

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Discussion Starter #9
Sketchy how often we are seeing pretty new Bosch rebuilds fail in these cars. UG. At least if it happens again, I can cry and whine all I want about that 17mm nut, but at least the alternator will be Free from FCP!
On that subject, do you remember if your was remanufactured here in US or Germany?
As mentioned in OP, I went with Amazon as they had last one in stock with no core return. This way I'll probably dig into old one and have my friend Sreten send me proper rebuilt kit from Germany.
 

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Mine was from FCP, I don't remember checking the box for this, but on their website it says made in the US:
Description
Details
  • SKU: BOS-AL0804X
  • FCP Euro ID: 95263
  • Made in United States
  • Quality: Remanufactured
OE Numbers
12311407440
MFG Numbers

Post up the proper German rebuild kit here if you have a moment. Thanks!
 

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Discussion Starter #11
Mine was from FCP, I don't remember checking the box for this, but on their website it says made in the US:
Description
Details
  • SKU: BOS-AL0804X
  • FCP Euro ID: 95263
  • Made in United States
  • Quality: Remanufactured
OE Numbers
12311407440
MFG Numbers

Post up the proper German rebuild kit here if you have a moment. Thanks!
Your response is helping my theory that the one I bought from Amazon is old stock remanufactured in Germany and hopefully better quality.
This is what Sreten recommended and used but when I searched here part#'s in US, the results were mixed. I'll probably have him buy it in Germany and ship it. Being small package the rates are quite reasonable.

regulator - BMW part # 12311713491 / Bosch part # 1 197 311 545
Bigger bearing - Bosch Part# 1 120 905 510 is common part# B17-99D (17x52x17)
Smaller bearing - Bosch Part# 1 120 905 525 is common part# 6203-2RS (17X40X12)

More info here:
 

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If you search the various websites using the voltage regulator you will see most run in the $350-550 range just for the VR. Then there are couple of sites like Schmiedmann where it is $87 and one on Amazon for $27 !! My guess is this is the cause of the early death of the remans.
 

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Discussion Starter #13
If you search the various websites using the voltage regulator you will see most run in the $350-550 range just for the VR. Then there are couple of sites like Schmiedmann where it is $87 and one on Amazon for $27 !! My guess is this is the cause of the early death of the remans.
Exactly. For whatever reason if you're in Europe and search the same part#'s you end up getting good quality VR and both bearings for about 50 Euros. I think with shipping I can have it here in US for around $75.
 
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