Voltmeter ???

[chockey]

Last week I noticed that my volt meter was really bouncing 14-18+ volts and checked the alternator, found that the pigtail was in poor shape so I replaced it. The problem was better, so I thought, when I have been driving it for about 20 minutes it starts bouncing again.
This morning I happened to notice that when it started bouncing again that the engine temp started to climb. The temp usually is about 210-220 but it went up to about 240. So maybe the belt on the alternator and water pump is slipping and giving me the problem. The water pump was put on last year and the alternator is 2 years old.

What are your thoughts or might it be something else, I appreciate your assistance.

Chuck

 

[smurfvet]

The battery should be around 14 to 14.2 volts in this weather, assuming a normal charge. I assume that when you turn the key on the voltmeter stays stable at approx. 14 volts. If the voltmeter is jumping higher when the engine is on, I would think the internal electronic voltage regulator or a connection on the regulator block is intermittent, forcing the alternator to go to intermittent full charge. How old is it? If it's original, this could be the problem. Since it improved somewhat with the new pigtail, I would look at what the pigtail connects to.

Since everything is in one package, more or less, you will have to separate (disassemble) the alternator and check the voltage regulator, connections, and for good measure the diode blocks, brushes and bearings.

For what a rebuilt Delco alternator is right now, go for the rebuild and save the old one for the numbers if it's a numbers-matching car.

I had the same problem with an older car and a tractor that had a separate voltage regulator. That solved the problem. The tractor was running upwards of 17 volts. The lights were real bright!

By the way, did you make it up to Watkins Glen for the opening day? I did, it was fun, and good weather. A lot of Vettes there too.

 

[chockey]

My voltmeter has been a steady 14+ volts til lately and it only starts bouncing after about 20 miles. The alternator is about 2 1/2 years old and it was a new one not rebuilt. I was thinking that the belt might stretch but it seems tight after running but it might be slipping, so I bought some belt dressing and will try that tonight. If this doesn't work I will probably be replaceing it, thanks for your thoughts.

The Vette is original except for the water pump and alternator so shes going to need some attention, paint, Gasket kit, seats and carpet. Had some carb work done but still the same Q-jet and new brakes.

A friend is teasing me to buy his 93 and she is a beauty, have 6 cars in the driveway now and my wife is very patient but I have the urge to own a GTO too. Its nice to have dreams.

I didn't make it to Watkins Glen yet this year but hope to be there for the vintage car races in sept., they are featuring the American Muscle car this year.

Thanks for replying
Chuck

 

[smurfvet]

One more thought- if the alternator is heating up after 20 or so miles of driving, which I expect, this sort of answers the intermittent contact question- the plastic parts in the voltage regulator are expanding at a greater rate than the metal conductors, causing an intermittent break in the regulator connection. Very common in electronics, and the hardest thing to find! If the alternator is that new, try a voltage regulator unit first- it's fairly easy to get to and change.

Good luck

 

[Robin7TFour]

the diode pack may be breaking down when the motor heats up the alternator

robin