Replacing Alternator on my 540i..Any tips?

Well...the battery light came on while on my way home from work yesterday. I already ordered the alternator (Watercooled), should arrive tomorrow. I already sourced a diy (http://www.bimmerboard.com/forums/posts/355405 ).

I think I got this down but wanted to know if anyone thats done this task before has any tips.

I narrowed it down to the alt because:

Battery is fairly new, replaced it in Feb 2010
Battery volt with car off: 12.2 volts
volts with car on & idling (after 1 min): 11.79 volts
volts with car on and approx. 3k RPM: 11.78 volts

So it seems like the alternator isn't charging the battery. I guess it's due anyway (106k miles, 500watt amp on board with 5 farad cap.)

So..Any tips? I appreciate any help/insight..Thanks.

Yep, typically OBC #9 should show 13.7V or higher with engine on. If you don't address the 500w AMP issue, your next alternator may follow the same fate. Either get a huge capacitor or Optima battery for it.

Right. I did forget to mention I have a 5 farad capacitor. Added this info to my first post..

Anyone else?

If you don't mind - how much was that water-cooled alternator? Was it a 120Amp unit? I've been wondering just what it will cost to replace on my 525 someday (hopefully a long time down the road) on my car.

Thanks

Originally Posted by Calicoastin

Well...the battery light came on while on my way home from work yesterday. I already ordered the alternator (Watercooled), should arrive tomorrow. I already sourced a diy (http://www.bimmerboard.com/forums/posts/355405 ).

I think I got this down but wanted to know if anyone thats done this task before has any tips.

So..Any tips? I appreciate any help/insight..Thanks.

I did it a few years back. In the above link I would take off the negative cable. If you take off the positive cable there is a good chance you could hit the chassis and weld your 10mm wrench to the cable and chassis which will make the battery explode.

I did it from the bottom side and didn't remove the fan or shroud. I also didn't have a tranny oil cooler in the way either, 6 speed has more room down low.
The alternator comes with the o-ring so you really don't need RTV.

Originally Posted by Turbo_525

If you don't mind - how much was that water-cooled alternator? Was it a 120Amp unit? I've been wondering just what it will cost to replace on my 525 someday (hopefully a long time down the road) on my car.

Thanks

525's don't have water cooled alternators.

Install a second battery with a battery isolator. A high CCA Optima yellow top should do the trick. Also when replacing alt,change out all belts while there off.

Actually, it's 150 amp water cooled. Got a reman one from ***********.com for $167.xx +$67.xx core. I did get charged $20 tax and chose overnight shipping ($37).

Originally Posted by thecushion

Install a second battery with a battery isolator. A high CCA Optima yellow top should do the trick. Also when replacing alt,change out all belts while there off.

I'm planning on r/r the belt as well. BTW, how many belts are on the M62TU? Just one right?

Originally Posted by Calicoastin

I'm planning on r/r the belt as well. BTW, how many belts are on the M62TU? Just one right?

I believe there are two belts.

Originally Posted by Calicoastin

I'm planning on r/r the belt as well. BTW, how many belts are on the M62TU? Just one right?

realoem.com

I just got bad news. I contaced the place I ordered the alt from ( th3 parts bin) .com and they now say the alt is out of stock so I won't be getting my part this week. They charged my card too...

I called yesterday to make sure they had it and they said yes. After I placed the order I called a few hrs later and they said it had already shipped. WTF... The place I ordered from is called the parts bin (dot) (C)(O)(M), all together. After I contacted them today they state "we will send the email right now to let you know"...again WTF!!

Man, it's been a bad week.

Guys...is it ok to drive the car with the battery light on? For how long. I havent' driven the car since it came on..

That's BS what they did! I'd be pissed as hell, you paid for over night shipping and they didn't even have the part? I hope they refunded your shipping $?

Originally Posted by Calicoastin

Guys...is it ok to drive the car with the battery light on? For how long. I havent' driven the car since it came on..

If it's fully charged and you turn off all of the electrical items you can get maybe 50 miles before the battery dies after the alternator stops charging.

Originally Posted by JimLev

If it's fully charged and you turn off all of the electrical items you can get maybe 50 miles before the battery dies after the alternator stops charging.

And, when it dies, it dies! (ask me how I know).

If you're going to drive with no alternator, I'd suggest the following:

• Put a spare charged battery in the trunk (to get you back home)
• Keep an eye on your battery voltage on your cluster
• Make sure your AAA membership is current

See my saga for my air-cooled 525i engine:
- One users' example of total electrical failure (AAA towed away) alternator repair (1) (2)

Originally Posted by Calicoastin

I just got bad news. I contaced the place I ordered the alt from ( th3 parts bin) .com and they now say the alt is out of stock so I won't be getting my part this week. They charged my card too...

I called yesterday to make sure they had it and they said yes. After I placed the order I called a few hrs later and they said it had already shipped. WTF... The place I ordered from is called the parts bin (dot) (C)(O)(M), all together. After I contacted them today they state "we will send the email right now to let you know"...again WTF!!

Man, it's been a bad week.

Guys...is it ok to drive the car with the battery light on? For how long. I havent' driven the car since it came on..

Talk to Ivan at this place "rmeuropean" This is where I got my alt when in went out.

Yes 2 belts is what needs to be changed.

Originally Posted by thecushion

2 belts is what needs to be changed.

If you're going to change the belts, you may as well consider replacing the tensioners & the idler pulley.

For details, do a thread search for 'tensioner' in the bestlinks.
- How to tell if you have mechanical or hydraulic belt tensioners (1) & how to switch from mechanical to hydraulic (1) and what is the difference between the two types (1) (2) & how to rebuild your hydraulic tensioners (1)

Here is more information about the alternator:
Common questions which need to be answered BEFORE you do an alternator and/or drive belt system overhaul:
- 1st: Physically, determine what type of tensioners you have (1)
- 2nd: Physically, determine exactly what alternator you have (1)
- 3rd: Determine which parts you need to buy for a complete drive belt system overhaul (1)
- 4th: Do the alternator and drive belt system DIY (belts, tensioners, pulleys, rollers, alternator) (1)

Alternator and Belt Drive DIYs:
- Removal instructions for the alternator & drive belt system of a 2002 525i
- Removal instructions for the fan shroud of a 2002 525i
- Alternator and Belt Drive DIY (1) (2)
- How to tell if you have spring-drive or hydraulic belt tensioners or both (1)
- How to diagnose noises coming from the drive belt system (1)
- One users' example of total electrical failure (AAA towed away) alternator repair (1) (2)
- Video of cold idle engine squeal (1)
- Recommended parts list for a complete belt drive system overhaul (1)
- How to make your own BMW special cooling & belt drive system counterhold tools (1)

Did it. I replaced the alternator. Will report details tomorrow since I'm too tired at the moment. Btw, I did not remove the fan clutch. :-)

Thanks for all your help..

Originally Posted by bluebee

And, when it dies, it dies! (ask me how I know).

If you're going to drive with no alternator, I'd suggest the following:

• Put a spare charged battery in the trunk (to get you back home)
• Keep an eye on your battery voltage on your cluster
• Make sure your AAA membership is current

See my saga for my air-cooled 525i engine:
- One users' example of total electrical failure (AAA towed away) alternator repair (1) (2)

good god who decided to tie that car down that way? lol

So would you say the alternator is a part on the BMWs like the radiotor? Its just bound to fail sometime after 90k. I'm asking because I'm at 94k on my 540 and just completed my cooling system overhaul. I was looking to see what the next part is I should replace before it fails. (this car is a money pit)

Originally Posted by bin01123

So would you say the alternator is a part on the BMWs like the radiotor? Its just bound to fail sometime after 90k. I'm asking because I'm at 94k on my 540 and just completed my cooling system overhaul. I was looking to see what the next part is I should replace before it fails. (this car is a money pit)

I had asked a similar question to ascertain WHY our alternators fail:
- Does an ATF leak onto the alternator cause it to fail? Can we test if this is true?

And, of course, I've asked how to TEST a failing alternator:
- DIY how to test a BMW E39 battery & alternator (discussion)

The answers that came back weren't exactly conclusive, so, I can only say that we'd really need more data on what fails on the alternators most:

a) Is it the bearings?
b) The diodes?
c) The regulator?
d) The coils?
etc.

Anecdotally, I'm guessing that most failures are the bearings. If that's the case, then I'd recommend you stock the bearings yourself, well ahead of the time your alternator fails. Luckily, they use standard-sized bearings, so stocking these $5 parts would be easy.

Then, when your alternator finally does fail, you can take it apart and replace the bearings quicker and cheaper than you can if you order a rebuilt alternator (which is what most of us do when faced with the sudden failure).

See also:
- How to test your generator (1) & how to determine exactly what alternator you have (1) & a DIY for replacing the E39 I6 alternator (1) (2) (3) (4) (5) or E39 V8 alternator (1) (2) (3) (4) & why you want to clean out the air-cooled alternator air duct & cooling vents (1) (2) (1) (2) & why rebuilding an alternator is preferable to replacing (1) & cn90 DIYs for rebuilding a 1998 air-cooled BMW Bosch alternator (1) (2) or his VW Bosch alternator (1) & cdawg246's quest for materials for a Bosch water cooled alternator rebuild (1) & Aioros' 1999 Valeo Alternator rebuild DIY (1) and his quest for materials (1) & Cn90's explanation of where to get hard-to-get alternator rebuild parts (1) & how to tell from the part number if a replacement alternator is actually rebuilt "by" Bosch (1) & a DIY for replacing the brushes in an (Audi) Valeo alternator (1) & a Bosch alternator bearing replacement from a 1997 MB S600 (1) & from a Range Rover (1).