trouble with the 85 charging system......
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Team Owner
Joined: Oct 2000
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From: I need a 4 door C6 Z06
CI 2-3-4-5-6-8-9 Veteran
St. Jude Donor '05-'06-'07-'08
trouble with the 85 charging system......
We were out last week and with the a/c on the voltmeter was dropping into the low 11's, with it off, high 12's......had it checked and they said the alternator was bad. its only a year old and under warranty so I swapped it out yesterday.......running at 13.8 at idle, high 12's with the lights on........this is my wifes car so Im not really sure where the guage normally runs........any ideas???
Racer
Joined: Oct 2004
Posts: 286
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From: Washington DC
I've had problems with my '85 alt, too. Converting to a later style GM alternator is on my to-do list. The earlier delcotron alternators just don't put s&$t out at idle. They do fine @ higher RPM's but can't keep up @ lower speeds.
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Your dash voltmeter may not be accurate, check the battery voltage with a voltmeter at the battery terminals and compare it with the dash voltmeter. The voltage regulator attempts to maintain 14.7 volts across the battery at all times. At idle, the alternator rpm is too low for it to be able to deliver its full amp rating, but unless you have an unusually high electrical load the battery voltage should be 14.3 volts cold, 13.3 volts hot at idle. If your alternator isn't charging, your red battery light symbol on the dash will light.
Thread Starter
Team Owner
Joined: Oct 2000
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From: I need a 4 door C6 Z06
CI 2-3-4-5-6-8-9 Veteran
St. Jude Donor '05-'06-'07-'08
Originally Posted by jfb
Your dash voltmeter may not be accurate, check the battery voltage with a voltmeter at the battery terminals and compare it with the dash voltmeter. The voltage regulator attempts to maintain 14.7 volts across the battery at all times. At idle, the alternator rpm is too low for it to be able to deliver its full amp rating, but unless you have an unusually high electrical load the battery voltage should be 14.3 volts cold, 13.3 volts hot at idle. If your alternator isn't charging, your red battery light symbol on the dash will light.
thaks guys.....I was getting the red light before the new alternator but I'll check the voltage now
Melting Slicks
Joined: Oct 2000
Posts: 2,491
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From: prescott AZ
The early alternators on the 85 to 88 cars just do not last. Both my 85 at 30,000 miles and my 88 at 31,000 had their alternators die. They were rebuilt using HD bearings (instead of bushings), finned heat sinks (instead of the smooth rear half of the body), copper paste to transfer the heat to the heat sinks and a couple other improvements which I can not think of because i am half sleeping now.
