Q&A with Kit Foster: September 18, 2014

Q. I have a 1977 Cadillac Sedan DeVille that has been in our family since purchased brand new. She has all the toys: power windows, seats, air, etc. She starts up fine, runs fast and kicks down OK. However, the generator light goes on and stays on. The next day the same thing happens. When it is cold the generator light is off; when it gets hot, the light goes on when it warms up. I have replaced the alternator, belts and battery, but the light stays on. A friend suggested it may have a voltage regulator built in. I do not see one on the firewall, but anything is possible. Why GM put a “Gen” light instead of an “Alternator” light is beyond me. Has anyone else had this problem?

— John Quattrocchi, Garwood, N.J.

A. Well, an alternator generates, just in a different way from a generator. I suppose they thought an “Alt” light might be even more confusing. As to your problem, I believe your car has a voltage regulator on, or in, the alternator. If the regulator was at fault, replacing the alternator should have taken care of it. I’m not sure how the “Gen” light is wired on your car. It’s possible that a bad connection, particularly a ground, is causing current to flow through the bulb when it shouldn’t. Bulbs are very simple: if there’s a voltage difference between the terminals, they light up in proportion to the amount of current flowing through them.

You can test the alternator function by connecting a voltmeter across the battery terminals. With the car off and cold, the battery should read about 12 volts. Start the engine, and you should see 13-14 volts on the meter. It will drop back as the battery charge is brought up and the charging rate slows. Watch to see if it drops suddenly when the light goes on. That will indicate a charging problem. If it doesn’t, there’s something else amiss in the car’s wiring.

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Q. I have a very nice pair of original (but not NOS) fender skirts I would like to offer for sale. However, I am able to identify neither the car nor even which of the “Big Three” makers they came from. Is there any resource I can access to identify them?

— Ronald Weinger, via e-mail

A. They look very “1940s,” but the Big Three skirts of that period typically had some type of bright trim. An exception was the “blackout” era at the beginning of World War II, and I’m thinking they might be 1942 Oldsmobile. Your sketch shows an overall length of 32 inches, and height of 10-3/4 inches. Thanks for sending the photo of the back side. Someone may be able to identify them from the clamping mechanism.

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Q. Regarding Mark Axen’s inquiry about 216 Chevy rear main oil seals (May 29), the original oil seals on many engines from the 1930s to the 1950s or later were made of asbestos rope impregnated with graphite. There are still many of these available at flea markets and other suppliers. There are also seals made of more modern materials, some rope-type and some lip-type neoprene seals. I would prefer to use one of the more modern ones, which are available from many suppliers.

— Charles B. Arnold, Newark, Del.

A. Thank you. I would be inclined to use modern materials, too, but if the car is driven as it would have been back in the day, the original type may suffice.

To submit questions to this column: E-mail angelo.vanbogart@fwmedia.com or mail to: Q&A, c/o Angelo Van Bogart, 700 E. State St., Iola, WI 54990-0001.

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