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A couple of months ago the wires that run from the external reg. to the alt. fried. So I ran new wires, got a new regulator, battery, and alternator. It was running fine then till a week ago I drove it to work and had to get it jumped at the end of the day, on the way home the instrument lights and headlights went out. Luckily only a block away from home. I got home and turned it off then went to start it again and nothing. So I test the battery with a meter it shows 13 volts but when I turn the lights they're real dim and it only shows 8 volts. When I jumped it the battery showed 13 volts, and at the alt. it went from 0-6 volts. I went to Autozone and they test it 23 volts! I got a new one put it on and the same thing happens, the reg. tested good too. What next? I'm sorry for the log post but I tried to give as many details as possible.Please help if you can.

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1971 Chevy El Camino 355 vortec heads RPM Air-gap avenger 770, Headman shorties, Dr. Gas X, delta flows
 

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I'm sorry I can't be of specific help-- but I had all, all sorts of trouble with my charging system when the car was using an externally regulated alternator. Unless someone else chimes in here and offers a technical explanation of your problem, I'd bring the car to your local auto electric guy and have him install a new/rebuilt internally reg'd 3 wire. I haven't blown a fusible link or anything since.
And check out your battery. I thought I had a bad ground or something, but in the end, another one of my electrical problems was that I just needed a new battery. I still use the batter disconnect (underhood type) that I installed, but, it starts right up and charges fine with a new battery and newer style internal reg alternator.
Sorry I couldn't be more specific.

Matt
 

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Yuu've done a great job of detailing it. What voltage do you read off the back of the alternator when the car is idleing? 13 volts on the large red wire? Is the idiot light coming on?
 

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Discussion Starter #4
Yes John, I did see the light come on but very dim. The alt. was 0-6 volts while it was being jumped by another car, it was just fluctuating. But today I replaced the ground wire and I'm charging my battery up and will see what happens.

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1971 Chevy El Camino 355 vortec heads RPM Air-gap avenger 770, Headman shorties, Dr. Gas X, delta flows
 

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At what terminal on the alternator did it go 0-6 volts. At the big bolt terminal you should have the same voltage as at the battery. I really don't think you should have 6 volts on any other terminal except maybe the voltage sensing terminal which is the one that feeds back to terminal #2 on the regulator (don't know alternator terminal or colour offhand).

To me, it sounds like the battery is bad. The battery should not read 13V and then drop that much when you go to start. A dead battery would read something like 10-11 volts and then drop when you put a load on it. With a bad battery it will usually run once started but sometimes the battery actually shorts out the alternator to the point it can't produce enough voltage either.

If it turns out to not be the battery go here to read a good post about troubleshooting the alternator. My post is on page 4.
http://www.chevelles.com/forum/Forum22/HTML/002353.html

Peter
 

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Discussion Starter #6
It was from the large red wire that bolts to the back of the alternator.I'm going to work now and will be working on it this afternoon when I get off. Thanks for all your suggestions. Later.

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1971 Chevy El Camino 355 vortec heads RPM Air-gap avenger 770, Headman shorties, Dr. Gas X, delta flows
 

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Discussion Starter #7
I think I got it guys, when I removed the negative cable from the block the bolt was sort of loose but I replaced it anyway and made sure it was plenty tight. It started effortlessly and showed right at 12 volts while running, the same at the terminal at the back of the alternator. With the car off it showed the same reading. But what do you think about the ground wire bolted to the block, is it alright there or should I put it back on the alternator bracket. I moved it mostly from cleanliness but it seems it could work loose with the engine torque. Any thoughts on that, it does have plenty of slack. I appreciate all your replies, thanks again I'll take it for a drive later on.

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1971 Chevy El Camino 355 vortec heads RPM Air-gap avenger 770, Headman shorties, Dr. Gas X, delta flows
 

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The ground wire is just fine where you have it. It really doesn't matter.
You have another problem. The reading off the red alternator wire should be higher when the car is running. It should be around 12 volts (battery voltage) when off. It should be around 13.5 to 14.7 volts when the car is running.
(have to run but get the alternator checked)
 

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I'm with John. The voltage must go up after you start the car. The battery voltage with the car on fast idle should definately be higher than with it turned off.

Peter
 

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A dimly burning alt light often is a sign of
the diode trio failing..(a common failure with internally regulated alt.)
Should your alt test bad I would also have the battery load tested as a failing battery can zap the altenator as Peter has stated.
Double check the wiring you ran and check running voltage as John stated...should see similar readings at the alt and the battery ...You can also turn on the headlights and heater and make sure the voltage bumps up at the battery slightly to compensate for the load.
jack
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by White71Elco:
A couple of months ago the wires that run from the external reg. to the alt. fried. So I ran new wires, got a new regulator, battery, and alternator. It was running fine then till a week ago I drove it to work and had to get it jumped at the end of the day, on the way home the instrument lights and headlights went out. Luckily only a block away from home. I got home and turned it off then went to start it again and nothing. So I test the battery with a meter it shows 13 volts but when I turn the lights they're real dim and it only shows 8 volts. When I jumped it the battery showed 13 volts, and at the alt. it went from 0-6 volts. I went to Autozone and they test it 23 volts! I got a new one put it on and the same thing happens, the reg. tested good too. What next? I'm sorry for the log post but I tried to give as many details as possible.Please help if you can.

<HR></BLOCKQUOTE>
Check your starter selonoid, these are often overlooked and can cause the problems your describing
 

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Discussion Starter #12
Well I bipassed the regulator and the volt meter showed 13.5 volts while running but if put the harness back on the regulator it shows 11.9-12volts. Should there be a ground wire to the regulator? the car starts fine with the wire bybassed on the harness. It still won't start the car at 12 volts.

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1971 Chevy El Camino 355 vortec heads RPM Air-gap avenger 570, Headman shorties, Dr. Gas X, delta flows
 

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The base of the regulator must be grounded.

If you bypass the regulator you should quickly see more than 13.5 volts. When revving the motor a little, you'd easily get >15V (probably around 17V-24V).

I don't understand how it starts when bypassed but not if connected. Did you run it for some time bypassed? The battery will take a while to be discharged so a quick connect/disconnect should have little effect.

Please go to the post I linked and read through the testing and voltage checks listed. Do the tests and voltage checks and report back with your findings, in the form of what you checked and the result you found.

If you read it you'll find the final problem was the wires at the alternator connector were reversed.

Peter
 
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