Late-Model Corral - January 2013

We answer your tech questions regarding Ford Mustang years ranging from 1979 to 2013!Flaming Filly
I met a fellow Mustang fanatic today in the parking lot of my bank. He has a 1989 Mustang LX 5.0L (with 240,000 miles on it) and I have a 1989 Saleen Mustang (with 110,000 miles on it.) We were comparing Mustang stories and he really got my attention when he told me that about a year ago his stock alternator burst into flames. The alternator had an internal short and was draining the battery overnight. Then one day he noticed smoke coming from under the hood. He opened the hood and proceeded to empty three fire extinguishers onto the flaming alternator before it quit smoking. My questions to you are: Have you heard of any other Mustangs of this era with such catastrophic alternator failures? Should I replace my stock alternator with an upgraded model to avoid a similar problem?
Ray Charlton
Corvallis, OR

Ford's alternators are referred to as an alpha-numeric "G" series. Early externally regulated alternators (found on all Mustangs up to '85) are 1G versions and max out at 40-55 amps. Your internally regulated alternator started with the 1986 Mustang and is considered a 2G unit. These put out 65/75 amps max. For 1994 (and 1995), the Mustang was updated to Ford's 130 amp 3G unit which features an internal regulator as well as dual internal cooling fans (the first alternator to not have an external steel cooling fan on the Mustang). The '96 and newer modular Mustangs will have a 4G, 5G, or 6G depending upon model (Bullitt, Four-Valve, Two-Valve, etc.).

The issue with Ford's 2G alternator is excessive resistance and poor internal design, which both cause heat issues bad enough to melt charging system wiring/connectors and in extreme cases cause a fire. When you buy a replacement 2G alternator from the parts store, they almost always come with a new charging connector pigtail, as the original is usually melted. I did away with the 2G in my 1090 Mustang over 10 years ago and haven't looked back. Upgrading to a 3G alternator is really simple and can easily be done on a vintage Mustang as well (shown here on a 1965 Mustang with a 1994 Mustang serpentine bracket setup). Your letter has even inspired us to go through the upgrade steps on the typical well-worn Fox-body, which you can find elsewhere in this issue.
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