Car Missing after installing new alternator

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  #1  
Old 01-13-09, 05:56 PM
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Car Missing after installing new alternator

My car quite on me today. 1990 mercury Marquise. The battery light came on the dashboard for the past couple of days. I figured it was a short or bad alternator. Finally today the light came on and then car stalled.

Jumped the car and the battery light stayed on but it stalled doing a U-Turn. Took out the battery and charged it for 7 hoiurs.

Later, I had the battery checked at Autozone and it came back good. Bought and alternator and installed it. Took the battery cable off and car continued to run.

Now the battery light does not come on. When I turn on all electrical devices the car starts missing after a while and then shuts off. Any ideas?
 
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  #2  
Old 01-13-09, 06:15 PM
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I am not a mechanic, but is the alternator the correct amperage?? Also triple check all connections. Other than that hope you get it working!!!
 
  #3  
Old 01-13-09, 06:16 PM
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It is very possible you have damaged the alternator by pulling the batery cable off with engine running. The ignition system needs 11 volts or more to work properly, if alt. is damaged when you load the charging system by turning on the accessorys it pulls the battery voltage down and kills the ignition system. Have the alternator tested, if damaged repair or replace.
 
  #4  
Old 01-13-09, 06:45 PM
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Missing after changing alt

I agree with wire twister you have probably damaged something by pulling the batt cable off. This method would work with a generator,but solid state electronics dont like surges. RW
 
  #5  
Old 01-13-09, 09:33 PM
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Hmmm. The battery is only used to start the car. Once it starts it switches to the alternator and starts charging the battery.

When I took the battery cable off, all electrical electrical (head lights, wipers radio etc) was off also.

However, I was taught by a mechanic to test if the alternator is working, take the cable off, turn on everything, headlights, defroster, radio wipers and if the car shuts off, the alternator is bad and is not producing enough electricity.

I don't think it fried my computer. I noticed it needed some oil also. After chatting with you guys, I may refrain from trying this test in the future. I'm glad I forgot to turn everything on.

I did google the information and there appears to be conflicting info on the web.
 
  #6  
Old 01-14-09, 05:21 AM
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Quote:"However, I was taught by a mechanic to test if the alternator is working, take the cable off, turn on everything, headlights, defroster, radio wipers and if the car shuts off, the alternator is bad and is not producing enough electricity."

on pre electronic ingnition vehicles you could do this with out much consequence to the vehicle, computors and electronics in general do not like the voltage spikes generated from this though. the battery acts as a buffer to help prevent voltage spikes.

if we're not supposed to eat animals why are they made out of meat?
 
  #7  
Old 01-14-09, 08:14 AM
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Originally Posted by Speedwrench View Post
Quote:"However, I was taught by a mechanic to test if the alternator is working, take the cable off, turn on everything, headlights, defroster, radio wipers and if the car shuts off, the alternator is bad and is not producing enough electricity."

on pre electronic ingnition vehicles you could do this with out much consequence to the vehicle, computors and electronics in general do not like the voltage spikes generated from this though. the battery acts as a buffer to help prevent voltage spikes.

if we're not supposed to eat animals why are they made out of meat?
Gee thanks for the analogy! The mechanic was my father. I did my first brake job, of course he was watching at 7 years old.

My skills are outdated but that's why I have the you guys and the internet.
 
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