alternator

**Stephen L.** · July 23, 2002, 03:42 PM

Re: alternator

You may want to consult the wiring diagram in your repair manual for proper wiring of the solenoid area.......

You could also pull all fuses to see if the charging load goes away and then replace one at a time to see if it returns. Also check for any devices that are not protected by the fuse block that could be power drains.

If you have an ammeter/VOM capable of 20 or 30 amps you could disconnect the battery and place the ammeter in series with the battery to see if there is a load with the key off...then on. THat may give you some direction finding the culprit. WHATEVER YOU DO ..... DO NOT ATTEMPT TO START THE CAR IN THIS HOOKUP!!! You will definitely fry the meter as the starter draws upward of 400 amps during a start cycle.

Good Luck.

**Duke W.** · July 23, 2002, 03:56 PM

Re: alternator

I believe your car has a three wire Delcotron. With the ignition off probe the two red wires (at the back of the frame and on the side connector) with a voltmeter. They should both show battery voltage. Now probe the brown wire. It should no show voltage.

With the ignition on the two red wires will show battery voltage and the brown wire should show about 3 volts. Run these tests and tell us what you get.

Duke

**Jack H.** · July 23, 2002, 07:21 PM

Re: alternator

Sounds to me like a comedy of errors in spare parts + workmanship....

If alternator is putting out full tilt, all the time, it's because the alternator 'thinks' the battery is discharged into the 'dirt'... Sounds like you're not an electrically oriented fellow, so I'd suggest you get a second opinion instead of going back to the shop that just worked on your car.

Now, multiple failures can & do happen, so all this 'could' be coincidence. But, the odds are reasonably slim. In most towns USA, there's a good ole boy auto electric shop that's been in business for years and does 'custom' work like wiring and maintaining police cars (a lot of factory aftermarket add-in equipment: lights, siren, radio, Etc.). Guys like this are well skilled, typically honest beyond fault (bidder/winner of public contracts) and can get to the bottom of things FAST and efficiently.

**Joe L.** · July 23, 2002, 08:18 PM

Re: alternator

Jack and Ed-----

Yes, and if you're anywhere near Hayward, CA (SF Bay Area) the shop that Jack just described is called Speedometer-Electric Service. Give them 10 minutes and they'll have your problem all figured out. I can almost guarantee it.

**Jack H.** · July 23, 2002, 08:52 PM

Re: alternator

Don't know the shop, but I know/trust Joe.... If poster had gone to such a place originally, they would have had original alt + starter out in 10-15 minutes, gone through and bench overhauled good as new, put 'em back in and probably BEATEN the cost of R&R + mass scale reverse assy line substitute rebuilt items poster paid AND used better parts to boot!

**ed hickey 32630** · July 23, 2002, 09:06 PM

Re: alternator

Hi Duke,

Both red wires have 12 VDC on them. With the ignition off,the brown has 0VDC. With the ignition on, the brown has 12VDC.

When I turn the ignition on, the electric radiator cooling fan comes on. I don't remember it coming on before.

Ed

**Duke W.** · July 23, 2002, 09:24 PM

Re: alternator

Another question: What does the voltmeter read when the engine is running?
If the charging system is functioning properly it should be about 14.5 volts.

You can use the voltmeter in the car, but also check it with a test meter.

Duke

**ed hickey 32630** · July 23, 2002, 09:35 PM

Re: alternator

I didn't start the car. I towed it home. The alternator was disconnected when I picked it up. I measured the voltages with the connectors disconnected from the alternator.

It is too dark to fool with it now. I will measure it tomorrow.

Ed

**Donald O.** · July 24, 2002, 09:54 AM

Re: alternator

Ed,

Race back to that shop and get your ORIGINAL STARTER & ALTERNATOR back!!!!
it might not matter to you now, but it certainly will later...to you or the next caretaker.

Don

**ed hickey** · July 24, 2002, 12:06 PM

Re: alternator

Duke,

I reconnected everything this morning. I made some voltage readings. Across the battery, with the engine off, I read about 12VDC. The red wires at the alternator read the same as the battery voltage. The brown wire is 0VDC.

I turned on the ignition and the brown wire goes to 1.5VDC. So I started the car.

With the engine running, the voltage gauge on the dash shows about 12VDC. So I assumed the alternator is not working. I verified this by putting a VOM across the battery, it still read about 12VDC.

With the engine still running, I measured the BAT lead on the alternator and it read 46VDC, as in forty six volts. I went back to the battery and it still shows 12VDC.

Then it fixed itself.The dash gauge went to about 14VDC. I measured across the battery and it was about 14.5VDC. I measured the BAT lead on the alternator and it read 14.5VDC. Repeatedly turning the engine on and off now shows everything working.

I put an induction type ammeter on the battery and it shows about 50A right after the engine starts and goes back to about 20A when the engine is running. I turn on the headlights and I see the inductive ammeter "twitch" and it still shows a 20A charge.

I am thinking that when the guy stuck the screwdriver to the solonoid he may have opened the wire between the solonoid and the alternator. Maybe the torque of the engine put the connection back.

Since the BAT wire should be a direct connection to the battery, the 46VDC should have blown out every light in the car, something must be open. I have seen a similar run-away alternator problem years and years ago with a Chrysler.

What do you think?

Ed

**Duke W.** · July 24, 2002, 09:40 PM

Re: alternator

Well, I'm mystified, Ed. The initial reading you took - 12v on the red wires with zero on the brown with the igntion off and 1.5 V with the ignition on sounds okay.

The 46V at the "bat" terminal blew me away. I don't know what to think, however, since it now appears to be functioning properly - 14.5V with the engine running - I would say take no action, but monitor it closely. The 20A rate to the battery tells me that the battery is low, so if you have a trickle charger, it might be a good ideal to give it a long, slow charge. That's about all I can come up with.

I have a fair amount of experience with Delco 10SI systems. My Cosworth Vega has one and the engine's unbalanced second order vertical shaking force beats the hell out of the alternator. GM had problems during development, but didn't solve them completely. The biggest problem is with the side connector. The vibration has wrecked the terminals, which I've replaced twice; the red wire broke off once, and I've had to replace an open stator once. Last year I had to replace the regulator (second or third, I forget) because the vibration had worn about .030" off the side of the spade that holds the red wire, which intermittently opened the circuit causing an intermittent overcharge.

The CV alternator mount and adjusting bracket have rubber bushings in an attempt to isolate it from the engine vibration, so it has a dedicated ground wire, and many owners have thought they had a bad new alternator because they forgot to connect the ground wire.

Your Corvette probably doesn't have rubber isolation mounts, so it would not need the ground wire, and V-8s don't create a severe vibration environment because all first and second order shaking forces and moments are balanced, but I'm always suspicious of the side connector on almost any 10SI application.

BTW the CV generates a 250Hz, 13g peak forcing function at 7000 revs. It's broken the alternator several times as outlined above and every piece of stamped sheet metal on the engine including the oil pickup tube - twice on that, too.

Duke

**ed hickey 32630** · July 25, 2002, 10:08 PM

Re: alternator

I haven't seen a Cosworth Vega in years. Actually, I haven't seen a Vega in years. I have a '65 Cyclone (Mercury Comet)with a built 289/271 in it. If the alternator doesn't have the large pulley on it, it will throw the rotor apart at around 7000 RPM.

To bad you can't upload a picture of the Vega onto the site. Sort of a "show and tell".

I took the alternator to MG Electric today. They tested it and found nothing wrong with it. I told them about the 46 VDC. MG said the only way that could happen is if the rotor would ground. They took the alternator apart and it looked like it went through WW III. They replaced the rotor. I put the car back together and everything appears normal.

An interesthing thing was with the old alternator, there was a 3 second or so delay before the dash gauges would work. In other words, the old alternator didn't seem to work for 3 to 5 seconds. The new alternator seems to work right.

I can't find anything loose or open or corroded. I drove the car around for about an hour with no problems.

The '82 has a ground wire on the alternator case. Probably ground to the dash or something since the alternator is not mounted in rubber.

BTW, I took your advice and left a trickle charger on the battery all day.

The aux fan switch decided to short at the same time the other problems started.

I am just going to watch the voltage gauge for a few days.

Thanks to all for the suggestions, including where to take it. Sometimes you can't pick the spot where it is going to break down. The place where it ended up was not my first choice to take a car either.

Ed

**Craig S.** · July 26, 2002, 07:53 AM

Re: alternator

Ed - you can see Duke and his Vega in the movie Contact, starring Jody Foster. He is in the scene where jody is driving along looking at the crowds of people gathering...midway through the movie....Craig

**Craig S.** · July 26, 2002, 07:54 AM

Re: alternator

I forgot to mention, I think he has a red shirt on, standing behind his car....Craig

alternator

alternator

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