empotoma

Hi All:
I did the following tests and believe that my alternator has gone bad after only a week in use.
I was hoping to get a second opinion from the group before I remove it and return it to the parts store?
Is there something else to check first?
Vehicle: Early ’86. Auto
Background Story:
Starter was clicking and not turning the engine over.
A local shop replaced the battery, reported alternator and starter fine. Said they cleaned cables.
Car operated fine for 2 weeks. Daily use to work (20 miles each way) and short errands around town.
Voltage read 14.3 ish when in use.
Heard bad sound from alternator after driving home from work.
Opened hood and watched as the bearings/crown dropped from back of alternator.
I personally replaced alternator with Delco unit. All back to normal.
Used car for another 1 week without a problem.
Car sat for weekend at friends house.
Car driven home (20 miles) by daughter. She reported car running well.
Two hours later went to use car, battery at 9.3 volts. No start.
Charged battery, went to bring to shop, within 1 minute car stopped. Battery drained.
Charged battery again to 12.6. two days later still at 12.6 (no drain)

Here’s what I checked: (From old thread by member jfb)
Alternator output post to battery positive. Continuity (Very low resistance. Same as touching probes.)

Alternator metal case to battery negative post. Continuity

Across battery. 12.6 V

Red connector wire (plugged in) to ground. 12.6 V (engine both on and off)

Alternator output post to battery negative. (engine off) 12.6 V

Alternator output post to battery ground. (engine on) 11.9 V and dropping. Shut engine off

Any suggestions more than appreciated.
Thanks
Ed

AGENT 86

From the bible http://members.shaw.ca/agent86/Charging%20System.pdf

jfb

11.9 volts engine running measured with voltmeter probes, one on alt output and other on battery ground (do you mean neg post?) indicates discharged battery and no alternator output. Dash battery symbol light should be on indicating both low batt voltage and no alternator output. If you placed neg voltmeter probe on the negative braided batt cable, then you could have a defective batt neg cable or bad connection between the batt cables and batt posts. Also possible that the wire connections of one or both battery cables is defective at the cable lugs (lugs go onto the battery posts and held there with a bolt).
Remove the batt cables (neg first) and clean the cable lugs, bolts and batt posts and replace (neg cable last). Everybody don't necessarily do what they said they did.
Find the alternator output wire where it comes up to the jump start bolt behind the battery (8 large red wires attached) and engine running feel the temp of the fusible link, not more than warm allowed. Link may be defective.
Worst case you have an intermittent problem and you have to be there when the problem exists. You can't fix something that isn't broken.

empotoma

Thanks jfb and Agent 86.
Since all tests pointed to the alternator, I brought it back to the parts store, told them my story and they handed me a new one! Said if I installed it and it didn't fix the problem they would check the system for me.
They suggested that the voltage regulator failed, and that it was not terribly unusual.
Put the new alternator in and everything seems normal!! Voltage went to 14.3 and stayed there. Didn't have time to test drive it but, am hopeful there's not something else wrong that might kill this one too.

Maybe I'll get to enjoy our recent run of good weather with the top off!!

Thanks again.

ED

Vestor

I think my alternator went out today. Came of the freeway and the car just died on me with no warning. Couldn't get it started and what ever juice was left in the battary died quickly.

Does you car seem to be working okay with the new alternator or did you ever change out the voltage reg as well?

Thanks,

Gregg

Johns87

Hello,
The Voltage Regulator is In the alternator.
You can take the alternator to an electrical shop and have them fix it or just replace it.
One thing to check is the batery. You can not test it properly until after you have charged it, though. Do a load test and see what you have got. A lot of people are hard to convince this to but if a battery completely dies, the vehicle will! The battery has to have enough current to energize the magnets in the alternator in order to recharge the battery. Also, a good 'Hard-Charge' on a 'dead' battery will sometimes 'bring it back'. The reason for this is usually on a battery that has sit and then 'appears' to be dead. The plates get corrosion on them and a good 'Hard-Charge' will knock-off a lot of that corrosion and the battery will again hold a charge.
The reason I explain a lot of this about the battery is because it could have been 'struggling' with a weak alternator, connections etc..
You should have the Alternator checked, battery charged and check for all the good conections on primary tension wiring.
Take Care and I hope this is helpful, -John