Couple problems

[MA-BMW]

Sometimes when I go to start my 88 325i, it takes a good 45 seconds of cranking then it slowly kinda comes to life. A bad sensor?

And when I am driving, if I have the heat on full blast, the lights (head lights dash lights) are dim and when I shut the heat off it brightens up, and at idle if I rev it up everything brightens up and the blower picks up speed. And it won't start up if I leave the blower on. Is my alternator dying?

[kenika65]

Yes, your alternator is not charging enough or your battery is not good or is the wrong battery for your car or you have a draw on the battery which is draining your battery. What are the cranking amps on your battery? I have 700-800 allways.

[MA-BMW]

What about the long crank time?

[SchnellerVert]

Check the length of the brushes on the altenator, or tension on the belt.

Long cranking time, Is it lack of fuel? Low battery which is turning the starter slower. With current low voltage issue I would say it's electrical, jump the car to another and turn it over. If it snaps right over it's electrical.

[MA-BMW]

It's only some times it does the long cranking thing. Like once every probably 5 times I start it.

[bimmerville]

im having the same issue if it is a draw on the battery how do we trace it??

[SchnellerVert]

It's a multimeter and searching each circuit for the one with a draw when it's off. a PIA.

[MA-BMW]

What you could do is put the meter between the negative battery post and negative battery cable, and pull fuses as you go along and watch the voltage (I think you'd want it on voltage) drop and when it drops you have found your draw. But some circuits will have a draw like radio and stuff. I think I read that in the Bentley Manual.

[Burning2nd]

should be in the 14.2v range dureing runing with everything on.. and hold 12v when off...

[bimmerville]

we actually went up and took a look at it today. First we wanted to see if there was an actual draw so we hooked the multimeter up to the battery and it reay 12.8 closed the trunk and let it sit for a few hrs and returned to find absolutley no draw from it whatsover so Im wordering if the battery is just to weak for the car?? The alternator seems to work fine beacause taken a completley dead battery and restored it to 12.8(car sat for a few weeks in minus temps) Any other suggestions maybe a bad ground somewhere?