Alternator or voltage regulator?

[mcurcio1989]

I feel like this is a bit of a dumb question but with it being 14* outside and needing my car to get to work, I'd rather be safe than sorry (and I troubleshooting in 14* is no fun). Realy maybe this thread should be called valeo or bosch alternator but anyways my battery light came on while driving home yesterday. I shut as many loads off as I could and made it home fine. I put a meter on when I got home (I know I can do that the computer but I had a meter handy). With the car off my voltage was 11.3V running I was 11.0V headlights on 10.9V etc. Its clearly not my battery and is an issue with the charging system. I'm just not sure if I should replace the alternator (I assume they come with a new regulator) or just the voltage regulator. I believe on these the voltage regulators house the brushes which leads me to believe that I would be best off with just the regulator. But it would be nice to have confirmation on that if any of you have had a similar issue.

It sounds like my car either has a valeo alternator or a bosch and they are VR's are not cross compatible. Is there anyways of determining (build date, options, vin, etc.?) what I have without inspecting it (car is 30 miles away at home) so I can get this on order now. I need my car to be back in action for my commute to work.

Thanks a lot!!

[StephenVA]

Yep it is the charging system. I do not know any way to determine Alt brand other the visual confirmation. Maybe others can offer suggestions.

Smack it with a rubber mallet and see if the brushes connect and it starts charging once again. Brushes wear old and build up carbon tracking which in turns into a charge on charge off condition that will fry most Regulators.

Options:
Replace with new
Rebuilt what you have
Replace with a proven re-Manufactured unit (Before you leave the store, make them test that it actually works, Ask for the amp and voltage readings , not just a green light that says "OK"))

[SlickGT1]

I just did my regulator. Put it back in, and cost me less than $40.

[upallnight]

Even if you can determine the alternator from a build date, how do you know if a previous owner(s) hasn't replaced it with a different brand alternator. I have a Valeo alternator that I just put in a new regulator (OEM Valeo), but I have a spare BOSCH which I also put in a new regulator in my spare part box.

The only way to check is to remove the alternator and confirm visually what is installed.

[SlickGT1]

I did it at 70k miles, had all service history for the SAV, and it was always dealer serviced. Never saw anything for the Alternator. That's how. lol.

[IgotBMW]

I just replaced our X5's alternator this past weekend. Not sure if the PO has ever changed it. It only has 86k miles so I'm assuming not. But when I took it out there was no markings on it. I replaced it with a new bosch alternator.




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[mcurcio1989]

Okay, so it sounds like a regulator should take care of the problem but it is a crap shoot as to if I have a valeo or bosch. Btw I have seen (via DIY pics) that many of the alternators do have a marking on the black plastic cover on the back. The difference is fairly obvious if you take that black, plastic fan housing cover on the back opff the VR's are different.

I bought a bosch and a valeo regulator and then I'm going to try and get home in time to inspect and see what I have and then cancel the one I don't need. If worse comes worse I will have to return the one I don't need.

[mcurcio1989]

Okay so I just got home and checked. I have the valeo 140amp alternator. There is a tag on the top of it on the metal housing adjacent to the plastic fan housing.

for reference my x has winter package, sport, nav, and xenon lights. My guess is they put the 140amp on winter package (maybe xenon affects it or a combination of both) cars to support those draws.

One concern I have is that it appears the power steering fluid reservoir is leaking on to the alternator and this is able to drip through the alternator housing and on to the rotor / windings. I hope that didn't degrade the insulation on the windings and short them out or something. I may yank the thing off tonight and tear it down to clean and test resistance across the windings. I hope I don't have to replace the alternator because I haven't seen the 140 amp units listed anywhere :/

[StephenVA]

You should fix the leak also while you are in there as the oil pouring over an Alternator will not "keep it cooler or lubed".

[mcurcio1989]

^Lol I thought that went without saying

I decided I would yank the alternator out last night and pull the regulator off so It could be ready to go in today when the parts come. As I pulled the regulator off the brushes wanted to stick to the rotor. I noticed a groove probably 1/32" thick where the brushes ride and "thought that's funny they would put that there as it makes it hard for the brushes to slide off" then fractions of a second later and to my dismay I came to the realization that this was wear on the rotor and the whole alternator needed to be replaced. I was able to source a rebuilt alternator locally and the OFHG as I wanted to swap that out while in there. I'm not proud of using a rebuilt alternator but at the end of the day that is what I was doing anyways just I wasnt going to check the bearings or anything else. SO maybe if anything it is better - at least that is what I'm telling myself. I'm fairly certain that there are no non-oe suppliers that even make parts for these so I'm telling myself its okay.

As a note for people making this repair. I was able to do this without removing the cooling hose at the top of the e tank. I left the fan in place and I did not disconnect the ps pump reservoir. I didn't fully remove the OFH just leaned it back enough to replace the gasket. Excluding parts run this all took about 2 hours. Of course if you are the kind of person who wants to scrub down the engine while you have these parts off it will take much longer as you will have to remove more parts. The serpentine belt was a huge pain to get back on with the fan there but I think it took substantially less time than trying to get the fan to thread back on would have. For some reason that always has me inventing new profanity for about a half hour.