Alternator eating 1986
Thread Starter
Instructor
Joined: Dec 2001
Posts: 147
Likes: 0
From: Riverside CA
Alternator eating 1986
Help! My 86 has developed a taste for alternators. About a month ago my alternator quit and, after about 2 weeks of down time, I replaced it with a well known rebuilt. At the same time the battery would not take a charge so, thinking the alternator had shorted the battery I replaced that as well. A week later the alternator stopped working and I replaced it again, that one worked for about 2 weeks and now I am near dead again.
With the new alternator I had 13.5-14 Volts. Now I have 11.5 V at the battery and also at the large terminal on the alternator (and falling). With the car running, if I lift the battery ground terminal everything stops. The dash gauge shows 11.2 VDC and the red warning light is ON.
It there something else I need to check or am I just getting bad alternators?????
Any and all help is appreciated
Bob Miller
Riverside, CA :auto:
[Modified by myblack864+3, 11:06 PM 6/28/2003]
With the new alternator I had 13.5-14 Volts. Now I have 11.5 V at the battery and also at the large terminal on the alternator (and falling). With the car running, if I lift the battery ground terminal everything stops. The dash gauge shows 11.2 VDC and the red warning light is ON.
It there something else I need to check or am I just getting bad alternators?????
Any and all help is appreciated
Bob Miller
Riverside, CA :auto:
[Modified by myblack864+3, 11:06 PM 6/28/2003]
Burning Brakes
Joined: Nov 2000
Posts: 855
Likes: 0
Re: Alternator eating 1986 (myblack864+3)
I don't know if this is any help, but when my alt died a forum member recommended finding a local rebuild shop and have them rebuild my alt. I took that advise and haven't had a problem. Last september when I was visting in so-cal I had a generator (corvair) rebuilt in Walnut, Ca. I haven't had any problems with it. When you take you alt to a shop they rebuild your alt so you get back the same one, and usaully they replace all of the diodes and bearing, the cheap Pep-boys alt only get replaced what broke. So if its only one of the three diodes then only one gets replaced and forget about the bearing getting replaced.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Alternator eating 1986 (myblack864+3)
Your alternator has no output and the battery is being discharged. This is the reason the battery light is on and the battery terminal volts is low. A car battery's state of charge can be told by measuring its voltage. 12.9 and above, fully charged, 12.0 and below, discharged. Get a battery charger and charge your battery up over several days or overnights. Using the alternator to charge the battery causes large current from the alternator for hours which heats the alternator up and shortens its life. First check your 3 amp c . fan fuse with an ohmeter. You could have a defective plug-in connector or an open fusible link. Check for 12v on both red wires on the alternator with the ign sw in run (one on the plug and the alt. output ) with a low power 12v bulb . A voltmeter draws such low current it might show 12v on each red wire but a defective fusible link may be blown but have conductive debris with high resistance across it. Both red wires have a fusible link.
[Modified by jfb, 9:40 PM 6/28/2003]
[Modified by jfb, 11:13 PM 6/28/2003]
[Modified by jfb, 11:17 PM 6/28/2003]
[Modified by jfb, 9:40 PM 6/28/2003]
[Modified by jfb, 11:13 PM 6/28/2003]
[Modified by jfb, 11:17 PM 6/28/2003]
