Reply With QuoteDefinitely alternator bad... change the brushes on it first... it should be part of regulator.
5-10 Grand Master
Damn low voltage
I am not sure what is wrong, if anything. My voltage has been low while driving - I can datalog it in my ECU and see about 13.2 - 13.5 volts usually, but low dips aren't uncommon. The OBC shows like 13.3, 13.5, 13.7, 13.86 sometimes. I bought a new battery as the one I had in my car was about 5 years old now and is a Duralast 48-DL (800 cca) and I bought a Duralast 49-DL (1000 cca).
I measured voltage at the battery terminals - 13.4 - 13.6v
I measured voltage at the back of the alternator to a ground, 13.6 - 13.7v
OBC reports the voltage mentioned above.
The alternator is a Bosch 140A I had put in about 4 - 5 years ago. I got it from BMA and it was either a new or reman, so it should be good - it was ~$200 with a core, so prob reman. Anything else I can check? Car seems to be running fine, the battery was getting elderly so I replaced it, and now I just want to see 14.2v pop up on the OBC like it used to a long time ago!
The belt is a little cracked and squeaks on cold mornings so I am going to replace that next out of default. The weird thing is if I drive from say 3,000 rpm and let off the gas (2nd gear) the volts will sometimes drop to 13.3 from say 13.7. Typically, in my mind, if I am letting off, the voltage in theory should increase since I am no longer squirting the injectors etc. But what the hell do I know!
Last edited by Jon K; 03-28-2007 at 10:32 AM.
4 Grand Master
Definitely alternator bad... change the brushes on it first... it should be part of regulator.
5-10 Grand Master
Even on a 4/5 year old Bosch 140AMP?Originally Posted by Tiger
4 Grand Master
Yep... I think they messed up in the first place. I haven't seen BMW Bosch alternator... but on Mercedes, on the back side of the alternator, there is two screws holding on the regulator... pull it out and see how short the brushes is... When new, it is like 1.25" long.
Bosch offers 2 years warranty on rebuilt... and LIFETIME warranty on their new alternator.
Regulators are cheap... like $17 or so.
5-10 Grand Master
Is the regulator easily accessible with the alternator in the car?
4 Grand Master
It should be... on the back of the alternator... take a look.
Grand Master
You'll have to take the plastic cage off methinks... the regulator will be noticable by a device roughly oval shaped with a raised circle in it.
Also you'll have to take all the vent tubes and plastic crap off it before you get anywherehave fun!
5-10 Grand Master
Bah it looks like I'd have to remove the alternator for best access. I may do it this afternoon in the parking lot. Just to check the regulator. What a pain.You'll have to take the plastic cage off methinks... the regulator will be noticable by a device roughly oval shaped with a raised circle in it.
Also you'll have to take all the vent tubes and plastic crap off it before you get anywhere
I don't have any plastic tubes/ducts.
4 Grand Master
Oh right! Duh... your turbo charger is in the way.
3 Grand Master
that alternator was pretty bleeding edge in 1990, and the lack of forced cooling might be why it is going south on you.
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