2002 BMW M3 alternator

JEFF SHAW

MEMBER
2002 BMW M3
6 CYL
2WD
AUTOMATIC
11,400 MILES

I have replaced alt about 5 weeks ago. This last week the battery light came on. I noticed if I rev up the engine about 4-5k rpms the battery light goes out. I purchased a new(reblt) alt and this one worked for about 10 miles and then light came back on. This one will not go out. Any suggestions? I had battery tested and it is ok. I put new belts on. Now if I put old alt in and rev it up to 4-5k rpm it works.

5 Replies

DOCHAGERTY

MECHANIC
9,601 POSTS

Jeff, where are you getting these alternators from?

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Saturday, January 2nd, 2010 AT 11:47 PM

JEFF SHAW

MEMBER
3 POSTS

I have to admit I was trying to save a buck and got them from O'Reilly's auto parts. These are rebuilt alts.

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Sunday, January 3rd, 2010 AT 2:07 AM

DOCHAGERTY

MECHANIC
9,601 POSTS

It seems trouble shows up in threes, you're are the third alternator failure from the El Cheapo alternator parts store this week! The unfortunate part is that I have had the same experience from some of the big name rebuilders and went through two on one car! An internal inspection showed the part had been cleaned on the outside only and then reboxed. I raised a stink, but I did not get paid for the work on replacement of the faulty alternator. Go with a Bosch rebuilt unit, keep the warranty card handy and good luck Jeff.

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Sunday, January 3rd, 2010 AT 9:35 PM

JEFF SHAW

MEMBER
3 POSTS

Thank you for all your help. I am going to get one today. One last question. The m3 oem alt is 140amp. I found a bosch alt with 200amp. Would this be better for my car since it has had issues with alt due 8k rpm red line?

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Monday, January 4th, 2010 AT 4:06 AM

DOCHAGERTY