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At What Mileage Did You Alternator Die?

05-11-2018, 08:30 AM
My Sonata is at 90,000 and Iím wondering if I should start saving up for the inevitable. I heard 100,000 miles is the average.

05-11-2018, 11:38 AM
I've had a few alternators fail over the years.

My most hated alternator was in my then wife's car - a 1982 Toyota Cressida. This car inspired my continuing dislike of Toyotas. I think of them as well assembled poorly designed cars for people who like to shop for refrigerators. The alternator in this car was placed low down near the exhaust manifold with very little access to air flow. My ex-wife avoided freeways/highways and therefore spent most of her time driving slowly on surface streets. For three straight years, the $%^# alternator failed on a hot August day. I'd get a call from my ex telling me all the dash warning lights were on and I'd have to go get her and fix the car.

A more interesting failure was a 1986 Mazda 626 my sister owned. The symptom was the automatic choke would stay on too long (which kept the car on fast idle for a long time). How could this be related to the alternator you may ask? Well Mazda in their infinite wisdom used the current off one of the didoes to power a heater on the automatic choke. This diode failed open, so no power was not sent to the choke heater. This mean the heated choke took a very long time to operate. The alternator's other two diodes were fine, so the alternator mostly worked, but at a reduced capacity.

My 1997 Expedition devolved a noisy alternator around 50,000 miles - it turned out the rear bearing was "loose" in the rear housing. I took it to a re-builder who fixed it by replacing the rear housing with one off of a "junk" alternator. This fixed the noise but the alternator failed completely around 120,000 miles.

My family owned a 1978 Ford Fiesta (the boxy German one) and the alternator stopped charging at around 100,000 miles. It was an easy fix since the regulator/brush holder could be removed from the alternator without removing the alternator from the car. Two screws and I pulled out the old regulator and installed the new one.

I owned a 1974 Jensen-Healey that originally came with a Delco alternator. When it failed (at around 35,000 miles) I initially though I was lucky. It was a GM product, so parts should be easy to get - right? Wrong. It was a European version and nobody carried a replacement regulator. I finally had to buy a used replacement alternator from a junk yard. Instead of another Delco, I got a Lucas alternator. It was still working when I last saw the car.

A weird alternator I owned was installed in a 1986 Mercury Sable. This car had the "Insta-Clear" windshield. The windshield had a thin nickel coating (it made the windshield look golden from some angle when in the sun). To defrost the windshield and A/C current was pulled directly from the alternator to apply a high frequency current to the nickel coating. This heated the coating and almost instantly defrosted the windshield. I loved the feature. However, it made the windshield expensive and as far as I know, no US manufacturers offer the option any more. Because they were using the alternator to supply A/C current to clear the windshield, it couldn't supply current to run the car and charge the battery at the same time. Therefore the car came with an extra high capacity battery. Even back in 1986 this was a $1000+ option (but I still loved it).

My most recent alternator failure was also a Toyota alternator. It did not completely fail, but at least one diode bridge failed which caused the alternator to whine. It wasn't able to charge the battery at idle, but if you rev'ed it up you could, so the car never actually failed.

I've also had to deal with several failed alternators on farm tractors, but their operating environment is so different I don't think you can compare them to automobile alternators. Just to show how old I am, I've also had to deal with actual DC generators on farm tractors. Compared to those, no alternator is bad.

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