alternator regulator replacement?
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Instructor
Joined: Sep 2008
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From: champion ohio
alternator regulator replacement?
my 84 corvette displays 11.4 volts on the volt meter readout. i replaced the battery and drove all day running errands. when i came home at night i pulled into the garage and 11.4 came up again. took the alt. off had it check and the guy said it was over charging and it could be a bad regulator. these are internal regulated are they not? how do i go about replacing one. am i on the right track?
Le Mans Master
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From: San Diego, Ca
Team Owner
Joined: Mar 2001
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From: Cincinnati, Oh USA
Start paying attention to red battery symbol light on the dash. It lights when the battery voltage is too high or too low. Normal engine running dash voltmeter should read 14.3 volts engine cold and dropping to 13.3 volts engine hot.
Alternators have a voltage regulator inside of the case that can be replaced, but it isn't the only reason why alternators have low or no output voltage. Regulators aren't expensive and worth a try if the brushes look ok. Rebuild kits are available from the previous link.
Alternators have a voltage regulator inside of the case that can be replaced, but it isn't the only reason why alternators have low or no output voltage. Regulators aren't expensive and worth a try if the brushes look ok. Rebuild kits are available from the previous link.
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
alternator
There is a heat thermister in the alternator voltage regulator. If the alternator thermister gets hot, it reduces the output of the alternator by a volt.
The alternator should put out 14.2 when cold, and as it warms up, you will notice that the output voltage diminishes.
If hot it goes below 12.3 running, with the air on, your brake lights off, radio on, and no headlights, it is not normal.
You can rebuild the alternator in about an hour if you don't dawdle.
Half hour to remove, hour to rebuild, and half hour to reinstall.
The only thing...............remember to pull the wire on the brushes out before you start it, or you buy another alternator.
The worst thing that can happen, is you buy another one from Summit racing for $100.
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From: Summerland B.C. Canada
Thread Starter
Instructor
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From: champion ohio
thanks!
thanks for the tips guys. i removed the alt took it apart and upon inspecting the inards i spotted a wire that was not connected. there are three wires on the side and the one in the middle was not connected. i soldered it an voila alt works. i think this might be a temp fix though and am currently in the process of buying a new one. anyone have that summit part number? i live 20 minutes from them. thanks guys!
Team Owner
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From: The light that never warms.
St. Jude Donor '12
If you are going to replace the entire alternator, I would seriously consider upgrading to a CS144. I did a write up on this in the tech tips section a few years back, but I'm unable to access it right now. Not sure if it is down or not. There is an AC Delco adaptor that you can use to put a CS144 in either an '84 or '85 Vette, and it is a much better alternator than the old SI you have. Maybe some internet searching will turn up more on this, it's been a long time since I did it.
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From: The light that never warms.
St. Jude Donor '12
Here's a good write up. The 17SI you have is the same size as the CS144, that's why the swap is so good. You'll have to find which CS144 is clocked right for your application, but that shouldn't be too hard.
