Alternator Light Flashing

Thu 26 Jul 12 22:03

Alternator Light Flashing

I have found that when I am on a long run on a motorway my alternator light sometime flashes on and off at about a rate of once a second. My voltmeter needle flicks back and forth as well. It seems to happen when travelling at a constant speed of around 60. It is not all the time and after I sort it as described below it may start after about 15 or 20 minutes.

At first I put it down to a loose battery connection as I tend to leave one terminal hand tight so that I can remove it if I'm not going to use the car for a week or so. Each time the problem happened I stopped and fiddled around with the terminal and everything was ok again.

I have now tighten the terminal properly but last weekend it happened again. But every time I stopped and fiddled around with the terminals it was ok again. However I found that stopping the car and starting again 'cured' the problem. I even found that if I slowed down to below 40 the light would stop flashing and I could speed back up to 60 and it would be ok for another 10 or 15 minutes.

Any ideas???

Sat 28 Jul 12 12:37

Re: Alternator Light Flashing

Have you checked the terminals on the alternator, not knowing if your pulley wheel is keyed to your alternator spindle, check to ensure the pulley wheel nut is clamped up tight so the pulley wheel is not slipping.

Could be dodgy Battery or Alternator.

Best of Luck.

Last edited by Daytona Vette on Sat 28 Jul 12 12:38; edited 1 time in total. [1 %]
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Barry - Daytona Vette

Sun 29 Jul 12 12:41

Re: Alternator Light Flashing

If the alternator is old then it may be the slip ring brushes are on their wear limit. I suspect they are probably bouncing off the rings at certain rpm.

Try reving the engine staitionary to the same rpm you were driving at when the problem occurred and see if it does it.

Give the alternator a good wiggle up and down at the pulley to see if there is any play in the bearings, this would have the same effect I expect if it was chattering about. You may need to slacken the belt to see the true wear in the bearings.

Jon

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82 Corvette C3 - Just needs waxing + total restoration!

Sun 29 Jul 12 17:48

Re: Alternator Light Flashing

Thanks for the ideas, I've been tied up on other things this weekend so haven't had the time to check but will do so as soon as I can.