High Voltage
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Instructor
Joined: Sep 2004
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From: Linton Indiana
High Voltage
My voltmeter light came on recently and the gauge shows 15.5 to 17 volts. It's a stock 85 Corvette. I thought when the alternator went bad the voltage went down. Last year while I was driving it the voltage was below what it should be, just under 13 volts. I let it sit over the winter, started it up this Spring and it's been high ever since. Any suggestions?
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Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Sounds like the internal regulator (inside the alternator) has died.
But you should check the alternator output with a digital voltmeter. With the engine running , check the voltage at the large stud on the alternator and also across the battery terminals. You should see something between 13.7v to 14.2 volts depending on the state of charge in the battery.
With the engine off, a fully charged battery should show about 12.8v.
If the alterntor is bad, get a good quality remanufactured unit. Some of the chain auto patrs stores versions are rebuilds and not remanufactured. I would recommend an AC Delco remanufactured alternator.
But you should check the alternator output with a digital voltmeter. With the engine running , check the voltage at the large stud on the alternator and also across the battery terminals. You should see something between 13.7v to 14.2 volts depending on the state of charge in the battery.
With the engine off, a fully charged battery should show about 12.8v.
If the alterntor is bad, get a good quality remanufactured unit. Some of the chain auto patrs stores versions are rebuilds and not remanufactured. I would recommend an AC Delco remanufactured alternator.
Thread Starter
Instructor
Joined: Sep 2004
Posts: 216
Likes: 4
From: Linton Indiana
Sounds like the internal regulator (inside the alternator) has died.
But you should check the alternator output with a digital voltmeter. With the engine running , check the voltage at the large stud on the alternator and also across the battery terminals. You should see something between 13.7v to 14.2 volts depending on the state of charge in the battery.
With the engine off, a fully charged battery should show about 12.8v.
If the alterntor is bad, get a good quality remanufactured unit. Some of the chain auto patrs stores versions are rebuilds and not remanufactured. I would recommend an AC Delco remanufactured alternator.
But you should check the alternator output with a digital voltmeter. With the engine running , check the voltage at the large stud on the alternator and also across the battery terminals. You should see something between 13.7v to 14.2 volts depending on the state of charge in the battery.
With the engine off, a fully charged battery should show about 12.8v.
If the alterntor is bad, get a good quality remanufactured unit. Some of the chain auto patrs stores versions are rebuilds and not remanufactured. I would recommend an AC Delco remanufactured alternator.
Forgot to mention the new one had a one year guarantee.
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Joined: Jun 1999
Posts: 14,924
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From: Merritt Ils Fl
I did check it with a voltmeter. Just like you said, from the alternator terminal to ground and across the battery. It measured the same as the meter on the dash, hovering just below or at 17 volts. I spotted some chrome alternators on ebay, 110 amps, brand new for cheaper than the remans. Do you think it would be a better deal?
Forgot to mention the new one had a one year guarantee.
Forgot to mention the new one had a one year guarantee.
If you are interested in a learning experience rebuild it yourself. Kits with super simple directions are available at most parts stores.
Last edited by Muffin; Apr 10, 2012 at 10:40 AM.
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
I did check it with a voltmeter. Just like you said, from the alternator terminal to ground and across the battery. It measured the same as the meter on the dash, hovering just below or at 17 volts. I spotted some chrome alternators on ebay, 110 amps, brand new for cheaper than the remans. Do you think it would be a better deal?
Forgot to mention the new one had a one year guarantee.
Forgot to mention the new one had a one year guarantee.
Don't buy a cheap alternator! If you drive the car regularly, a cheap unit will probably not last more than a few years. I'll bet the fleabay uinit is most likely an offshore rebuild with a chrome-plated case; you will get what you pay for.... Most any reman alternator bought at parts stores like AutoZone or O'Reilly's will have a 1-year warranty.
Rockauto.com shows two AC Delco alternators for an '85; one is 108 amps output (p/n 3342311), the other is 120 amps (p/n 3342180. Either one is under $100.
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Instructor
Joined: Sep 2004
Posts: 216
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From: Linton Indiana
Well, to tell you the truth, I hardly ever drive the Vette anymore. I mainly just start it up once in a while and drive it for a few miles to keep the oil stirred up. When something's wrong with it I still want it fixed so maybe I can sell it some time. I've been driving my gas mileage car lately since we've had $4 gas, Vette sits in garage.
I bought a new mini starter for it a couple of years ago, I wonder if it was an oriental product also? It seems to work better than the original...
I bought a new mini starter for it a couple of years ago, I wonder if it was an oriental product also? It seems to work better than the original...
Last edited by joe wilson; Apr 11, 2012 at 03:19 PM.
