4.6is Low Voltage?

[1Kurgan1]

Bought this back in August. I didn't plan on it having a bad alternator, but it did. So I yanked the reman'd one that had 2,000 miles on it out of my e39 and put it into the x5. Since I parked my e39 for the winter, I figured I'd just buy another alternator for it later.

Drove the x5 for a few months, but parked it in December for some rear suspension work. Got it finished up recently and checked the voltage and it's charging quite low. It seems to charge constantly around 12.8 - 13.0. But it can vary anywhere from 12.4 to 13.5. Had the battery tested and that checked out good. Does it seem like my 2,000 mile alternator is dead? That's what I'm fearing, but just want to see what others have for ideas.

[williamx5]

Originally Posted by 1Kurgan1

Bought this back in August. I didn't plan on it having a bad alternator, but it did. So I yanked the reman'd one that had 2,000 miles on it out of my e39 and put it into the x5. Since I parked my e39 for the winter, I figured I'd just buy another alternator for it later.

Drove the x5 for a few months, but parked it in December for some rear suspension work. Got it finished up recently and checked the voltage and it's charging quite low. It seems to charge constantly around 12.8 - 13.0. But it can vary anywhere from 12.4 to 13.5. Had the battery tested and that checked out good. Does it seem like my 2,000 mile alternator is dead? That's what I'm fearing, but just want to see what others have for ideas.

Good day!!

Hmmm, I thought I was the only one that would pull parts from one, to use on another... My 2002 4.6is has the mirror from the 2004... Now that the 2004 is on the road, I had to pull the mirror from the 2006 to use on the 2004... Fun stuff... Figured out that you don't have to do anything to get the glass off the mirror base... Just a gentle pop with a flat screwdriver... Ummmmmm, if yours is broken, buy one!!! Don't go borrowing your neighbors just cause it's easy to get them off... Ahem....

The alt output is a little low, but still in the normal range... Very low end of the normal range... Can you hook up INPA and watch it on your laptop when driving around... Demand might make the output higher... Sitting at idle might not pull that much over your 13.5V...

Cheers!!!

[squidzilla]

I would plug in your obd2 Bluetooth adapter and monitor it on one of the many android apps out there. My e46 started showing 12.5 volts and I kept an eye on how much it was charging and saw it slowly go down. After a few months it was only charging at 11.5 volts.

I emailed a guy that rebuilds alternators and sells the parts, and he said it is probably the brushes in the voltage regulator going out. Either I can replace just the brushes myself for about 5.00 or I can replace the entire VR. I found a good deal on a new Valeo open box VR and went that route for half price. If you change the VR inspect the rotor and make sure it is not showing any plastic. If it shows plastic the rotor is done.

[1Kurgan1]

Yeah, I move parts around as I need :P You don't even want to hear about my snowmobile project, lol.

Anyways, I don't have an INPA setup, and don't really want to invest in an old laptop and such to set that up now. But I did just order a bluetooth OBDII scanner since I do have a cellphone. We'll see what that says.

Today though I went and connected the battery again. Reading before connecting it was 12.8v. After I put the terminals on it was 12.4v, is that amount of draw normal? It does seem like a small amount and there are a lot of electronics in these things, so wasn't sure if that's excessive.

Anyways, fired it up and it was charging at 12.8v. So I took it out for a 45 min drive, did some in town driving, and hit the freeway as well. No CE lights, no dummy lights, no sounds, drove great. But get back home and check voltage at idle and it was still only charging at 12.8v. I'll have to check when that app gets here, since I'm not gonna force someone to sit back there and give me voltage readings as I drive, LOL.

It's just strange, the thing drives great, and with no alt light coming or or CE lights. It makes me feel like it's just fine.

[X53Jay4.8is]

Originally Posted by 1Kurgan1

Yeah, I move parts around as I need :P You don't even want to hear about my snowmobile project, lol.

Anyways, I don't have an INPA setup, and don't really want to invest in an old laptop and such to set that up now. But I did just order a bluetooth OBDII scanner since I do have a cellphone. We'll see what that says.

Today though I went and connected the battery again. Reading before connecting it was 12.8v. After I put the terminals on it was 12.4v, is that amount of draw normal? It does seem like a small amount and there are a lot of electronics in these things, so wasn't sure if that's excessive.

Anyways, fired it up and it was charging at 12.8v. So I took it out for a 45 min drive, did some in town driving, and hit the freeway as well. No CE lights, no dummy lights, no sounds, drove great. But get back home and check voltage at idle and it was still only charging at 12.8v. I'll have to check when that app gets here, since I'm not gonna force someone to sit back there and give me voltage readings as I drive, LOL.

It's just strange, the thing drives great, and with no alt light coming or or CE lights. It makes me feel like it's just fine.

You Need to swap in a quality remanufactured premium alternator and call it a day.

[1Kurgan1]

Originally Posted by X53Jay4.8is

You Need to swap in a quality remanufactured premium alternator and call it a day.

Which ones would that be?

And I'd really hate to considering this ones got a whole 2,000 miles on it. I'll have to do more testing before I decide to bite that bullet and throw hundreds more at something that just had hundreds thrown at it (since this alt came from my e39, means I essentially would have to buy 2x alternators, since that needs one as well).

[X53Jay4.8is]

My point being you are still short one alternator for the vehicles you have. You have two BMWs and one working alternator correct? The one that has 2000 miles on it where did you you acquire it from? What kind of warranty did it come with? Most of the premium remanufactured ones come with a 2 year warranty in the event it fails in service. Bosch Premium Remanufactured.

[1Kurgan1]

Originally Posted by X53Jay4.8is

My point being you are still short one alternator for the vehicles you have. You have two BMWs and one working alternator correct? The one that has 2000 miles on it where did you you acquire it from? What kind of warranty did it come with? Most of the premium remanufactured ones come with a 2 year warranty in the event it fails in service. Bosch Premium Remanufactured.

Nope, I'm not. But I am back with an update. Turns out the nut was a little loose on it. Tightened it up and 14.6v. Exactly why I didn't just shell out money. I'm not trying to sound snappy or anything and wasn't before. But I know new parts fix things, but it's not just black (broken) and white (working). There are many things that can cause low voltage. Like a massive draw from a broken ground wire (fixed numerous vehicles with that before), or in my case, just a loose nut.

I knew what your point was. Mine was that if the alternator isn't bad, I'm not replacing it. And that I wanted to make sure that it was 100% a bad alternator before throwing money at a problem that didn't need it.

I was talking to my friend about this and he asked me if I checked that plastic nut. Which is what lead to me solving the problem. I wasn't making the thread to be told to replace my brand new alt. I was making it to see if anyone had a tip like my friend did (which is exactly what my first post says).

Not that I didn't expect that response, just was hoping it would be, "alt's probably bad, but it could be a few of these other things". Anyone could have told me to replace the alt just by me saying the voltage is low, I was looking for more niche things that could be causing it before I bit the bullet.

Either way, if anyone else is coming across this issue. Make sure that plastic nut is tight on the alternator.

[bcredliner]

The majority of the time a new thread goes from a question to new part solutions, some that can be resolution and likely some that are off the grid, all skipping the troubleshooting phase. The intent is to be helpful. I think it is important to read them as directional still requiring troubleshooting verification.

Based on my experience the first thing I do is check my work if I have just replaced a part and I am experiencing similar or the same symptoms again. In this case next step would be to monitor real time voltage and/or spikes at the cluster with lights radio and fan running and compare to realtime voltage at the alternator. That would put focus on the alternator and might have uncovered the loose nut.

We have to remember that input depends on how many are responding to our threads and we don't know if input has any credibility. So a variety of sources, like BMW techs, friends, etc. are always best practice before locking in on a course of action. Odds are much better that we take the right course of action with this process but there will be times the collective input is still off target or doesn't include something like the plastic screw.

I haven't heard of the loose nut cause but thanks to your update thread readers will be contributing that to others in the future.