BimmerFest BMW Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
How's it going yall?

Purchased a 81 320i last month, been working to get it into good shape. Most apparent issue was had to jump the car to start at time of purchase, therefore replaced the battery and alternator with O'Reillys auto parts. Been having an issue where my battery light stays lit and now the car won't start without a jump, idles rough and then ends up dying even while driving.

After 2 battery replacements and checking the alternator I say it is safe to rule that out.

Any suggestions? Similar issues?? I need to diagnose it and it's been a pain in the ass

Thanks bimmer fam.
 

·
D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
Joined
·
30,749 Posts
If the battery light is lit, the alternator is either bad (yes, the rebuilt ones can be dead right out of the box) or it has a really poor/severed connection somewhere. Get a voltmeter and check for yourself if you have 13.5+ volts at the battery while running. If not, your search begins for that bad connection.

Did O'Reillys test the alternator with it in the car and running?
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #3 ·
If the battery light is lit, the alternator is either bad (yes, the rebuilt ones can be dead right out of the box) or it has a really poor/severed connection somewhere. Get a voltmeter and check for yourself if you have 13.5+ volts at the battery while running. If not, your search begins for that bad connection.

Did O'Reillys test the alternator with it in the car and running?
Thanks for your response. I had the battery checked and they said it had the right voltage, no amps though. So I replaced that with a brand new battery..
No o Reilly's only tested it once it was out
 

·
D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
Joined
·
30,749 Posts
If you can limp it down to O'Reillys again, get them to test the charging system with the car running. You'll find you are running off the battery alone. It may be as simple as the excitation wire not supplying voltage to the unit, or as bad as the regulator having no connection to the electrical system. THEY need to test it in the car to see it's not working, whether it's the fault of the alternator, or the electrical system.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #5 ·
Update..had a mechanic look at it and he told me the mounting bracket is the issue. Too much slack in my alternator.
Any similar issues?
 

·
D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
Joined
·
30,749 Posts
Could be. If the alternator belt was loose enough to cause that much trouble, I would think it would be howling since it would be slipping a massive amount. Ask your mechanic if a shorter belt would work. These engines have notoriously weak tensioning adjustments for the ancillary pieces like the alternator and power steering pump. They seem to be out at the limit of adjustment even with a new belt. Also, some alternator mounts (I'm not sure about the E21) have rubber bushings that fail, letting the alternator twist cockeyed to the belt. There's no way to fix that but replace the bushings.
 

·
Registered
Joined
·
2 Posts
fuel pump fuse keeps blowing

hi guys,

i have an electrical issue with my '82 320i. engine runs fine, but the furl pump fuse gets very hot and blows after a short time.

any ideas for me???

also, the wiring diagram i have does not have the correct color codes to ring out the wires and let me find the short readily.

any sources for a truly correct wiring diagram??

so many thanks!!

guil
 
1 - 8 of 8 Posts
Top