Battery light on..

Hello guys!

I changed my IDLE PULLEY, BELT TENSIONER and belt a few days ago then my car was running great. But here is the problem. All of sudden my battery lights keep coming on and off irregularly
What's the problem?? Could it be I replaced the parts with cheap one which was on the ebay?? or alternator is bad?? anyone having same experience?? help me out guy!!

If I need to change the alternator, is that easy?? I am really clumsy lol


P.S: I have a 2002 530i and my battery was replaced a month ago.

Originally Posted by wegotseven

If I need to change the alternator, is that easy??

You need to check the alternator and battery again:
- How to test a BMW E39 battery & alternator

Here are DIY references for my 2002 BMW 525i (more in the bestlinks):
- 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)

Did you tension the belt properly, it could be slipping.

Originally Posted by JimLev

Did you tension the belt properly, it could be slipping.

Hi Jim,

Can you 'tension' a belt?

I was thinking that he might have put the belt on wrong ... but can you possibly even tension it?

My belt system, for example, with two mechanical tensioners, appears to be non adjustable.

Originally Posted by bluebee

Hi Jim,

Can you 'tension' a belt?

I was thinking that he might have put the belt on wrong ... but can you possibly even tension it?

My belt system, for example, with two mechanical tensioners, appears to be non adjustable.

yes you can tension it. There is one 'bolt' you turn to tension and one you turn to lock. There is an auto tensioner but there is still some level of mechanical tensioning by turning these 2 bolts and locking it in place.

Originally Posted by bricas45

yes you can tension it. There is one 'bolt' you turn to tension and one you turn to lock. There is an auto tensioner but there is still some level of mechanical tensioning by turning these 2 bolts and locking it in place.

On a six-cylinder e39? Where?

Originally Posted by bricas45

yes you can tension it. There is one 'bolt' you turn to tension and one you turn to lock.

I don't understand.

A picture of my mechanical tensioner from Oembimmerparts is below (from my alternator & belt-drive overhaul).

The only bolts I know of are the two that hold it to the engine (neither of which is 'adjustable') and, under the cap, the center bolt holding the pulley in place.

Which are those 'tensioning' bolts you bespeak of in this picture?

The tensioners have changed so many times that unless you look the car up you don't know what it's got.
Bluebee, your pic is of the AC tensioner.
Here is the alternator, waterpump, PS pump tensioner setup.
http://www.realoem.com/bmw/showparts...90&hg=11&fg=18
It looks like there is an offset bolt in the upper left idler that may be used for the tension adjustment.
The V8 tensioners are completely different.

Originally Posted by JimLev

It looks like there is an offset bolt in the upper left idler that may be used for the tension adjustment.....

That idler is offset, yes, but it only fits onto a notch in the alternator bracket one way and isn't adjustable.... at least on my M52TU.

Originally Posted by pleiades

isn't adjustable.... at least on my M52TU.

Here is a picture of BOTH my tensioners (from that same alternator thread).

At least for my 2002 M54 engine, I don't understand 'how' they're adjustable ...

I'm not sure how the I6 is set up...but on the V8 (M62/M62TU) you tighten the tensioner by using 2 sockets, or 2 wrenches, or a combination of the both. You need a 17mm socket or wrench and a 13mm socket or wrench.

When the 13mm bolt is loosened (it's the one that goes thru the slotted part that allows for movement to loosen or tighten)...you place a 17mm socket or wrench on the 17mm bolt (on the right) and turn/push it counter clocwise. This puts tension on the belt/pulley...while turning/pushing the wrench on this 17mm bolt....you tighten the 13mm bolt preferably with a socket wrench.

This is how you put tension on the pulley for the V8. For those that have the I6...is it the same type of set-up?

(image by Arbysnight from BimmerBoard)



>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<

(#8 = the 13mm bolt & #9 = the 17mm bolt in the image above)

Originally Posted by QSilver7

....This is how you put tension on the pulley for the V8. For those that have the I6...is it the same type of set-up?

Best I can tell, it's not adjustable on the i6 cars.

Originally Posted by pleiades

Best I can tell, it's not adjustable on the i6 cars.

OK. So I looked it up.

Much to my embarrassment, I had already summarized the answers, not so long ago in post #71 of this thread:
- Do we have hydraulic or mechanical serpentine polyribbed drive belt tensioners?

Originally Posted by bluebee

For the record, here is a nice picture of the adjustment arc of the V8 hydraulic tensioner today:
- E39 (1997 - 2003) > AC tensioner installation

NOTE: The I6 hydraulic tensioners do not have this adjustment arc.

See also:
- 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)

Originally Posted by wegotseven

Hello guys!

I changed my IDLE PULLEY, BELT TENSIONER and belt a few days ago then my car was running great. But here is the problem. All of sudden my battery lights keep coming on and off irregularly
What's the problem?? Could it be I replaced the parts with cheap one which was on the ebay?? or alternator is bad?? anyone having same experience?? help me out guy!!

If I need to change the alternator, is that easy?? I am really clumsy lol


P.S: I have a 2002 530i and my battery was replaced a month ago.

Too much of a coincidence. I think yes, the ebay parts are not good and/or you installed something incorrectly, preventing the alternator from doing its job.

Thank you fellas for quick replies.
Eventually My batter light is on permanently. I guess my alternator is bad. Is alternator making some noise if it's bad??
Mine has a little bit noise.

Originally Posted by wegotseven

Is alternator making some noise if it's bad?

After all the reference links, now the advice becomes super simple.

STEP 1:
CHARGE THE BATTERY!
NOTE: If you don't have a battery charger, buy one. You'll use it for decades (mine is 25 years old, for example, and has been used many many many times over the years).

STEP 2:
PUT JUMPER CABLES IN THE TRUNK!
NOTE: If you don't have jumper cables, buy them! Mine have to be thirty years old, and they work just fine and have been used dozens of times as needed.

STEP 3:
DRIVE TO AUTOZONE!
NOTE: Have someone follow you in a separate car in case you need a jump.

STEP 4:
ASK FOR A FREE BATTERY/ALTERNATOR TEST!
NOTE: That will give you the answer you seek!

I about to order this one : http://cgi.ebay.com/ebaymotors/NEW-A...item45f4d4a1b6

Is that right one?

Well after changing my belts & Pulleys noe my battery light is flashing irregular, did you ever figure out what your problem was?

Originally Posted by shalyndavis23

Well after changing my belts & Pulleys noe my battery light is flashing irregular, did you ever figure out what your problem was?

Did you see this in your owners manual? An illuminated battery light indicates that the alternator or other charging system components are the CULPRIT:

yeah the bolt was loose!

It was my alternator. I changed my alternator and the battery light is gone.
Thank you guys!