Wait Until Alternator Die to Change it?



Hi Everyone,

Thank you for any help or suggestion.

I kinda know that my car alternator is failing, but not sure when it’s going to die. I don’t want to just change it out right now since I’d prefer to extend its use to its full.

My question is if I keep using it that way and wait until it dies, will the car be affected in anyway the MOMENT that the alternator dies WHILE I’m driving?

I was told that with old cars, they won’t “die” when the alternator die while driving, but you won’t be able to restart the car after you stop it. AND with new cars, they will die even while you’re driving it. Is this true?

I’m driving a 1999 Toyota, Sienna.

Thank you very much,



More info,why do you think it is dieing?
Have you had battery check correctly,wires and connections cleaned?


If the alternator is failing, consider this:

When it fails, it is unlikely to take place in your driveway.
More likely is a failure while driving, perhaps while in the left lane of an expresssway, in the midst of 18 wheelers. At the very least, you can expect to add a towing bill when the alternator fails on the highway. Or, you could wind up in a serious accident, due to loss of power.

When it finally fails, it will likely take the battery with it. Right now, you might be able to save the battery that is being weakened daily by the bad alternator.

When it fails on the highway, you may not have a choice regarding where to have it repaired.

It is your decision, but I personally see no advantage to deferring a repair that is going to be needed very soon anyway. The disadvantages of deferring the repair are numerous.


I had a 1982 Toyota Cressida, with an alternator I felt was “on its way out”. I postponed alternator replacement, as the car had 80k miles. One day, I heard a loud pop under the hood, and the car died. The voltage had spiked, frying EVERY computer, the radio/tape player, every relay (including windshield wiper, Auto Climate control). Total repairs came out to over $1200 (parts only- I replaced things myself).

Dont take chances with the Alternator or Voltage regulator.

By the way, I used to own a twin engine plane (Piper Seneca). “Accesories” like alternators, magnetos, and vacuum pumps are swiped out when engines get overhauled whether they “need it” or not. Like VDCDriver said: Where will you be when it fails?


Your car runs off the battery. Your alternator keeps the battery charged. New car or old car, when the alternator dies the car will keep running until the battery is completely depleated. Whereupon, if you’re in a bad neighborhood you will get mugged. Or worse.

At best, when the alternator goes it’ll take the battery down. At worst, you’ll get mugged too. There is no “upside” to waiting to change a failing alternator. You accomplish nothing by waiting. And it may even cost you more.

Besides, if it fails in the middle of the weekend you may have to have the car towed to a shady garage instead of using your trusted mechanic.


Replace the alternator now.


“I kinda know that my car alternator is failing, but not sure when it’s going to die”.

How do you know it is failing - symptoms? Before changing out the alternator I’d like to know it is failing. Sometimes an old battery is the problem, not the alternator. If your Sienna isn’t holding a good charge, when was the battery replaced? Load tested?

If you are getting bearing noise from the alternator, replace it. Otherwise you need to be more sure of the diagnosis and rule out a battery going bad, check for corrosion on both ends of both battery cables, or old cables that need replacing.


If you truly know it is dying, replace it. Don’t wait. My guess is with a Sienna you have kids who won’t be too happy (or safe) sitting around waiting for a tow truck when it does fail.

If you were to follow the advice of my mechanic, get a NEW alternator, and don’t skimp. He swears that they have constant problems with remans on Toyotas (on the other hand, he says that he can put remans in Fords all day long without worries - go figure).


Replace it NOW, if it fails, the belt will likely need replacing as well. I conduct work shops in Reliability Centered Maintenance (RCM), and this is one item that usually gives sufficient warning when it is going to fail, and should be replaced PRO-ACTIVELY.

The last time I had a failure without warning my wife and I were driving on a freeway with the young baby in the back. It was Sunday afternoon between Christmas and New Year.

We were in the left lane at 65 mph or so when the alternator went with a loud scream. The weather was bittery cold, and only good luck of being close to a service center with repair facilities saved the day. No cell phones then. I had to walk up there to get a tow.

What also saved the day was that we had a Dodge Dart with very common electrial components. We were towed into the shop and warmed up in the restaurant where the baby kept sleeping soundly. Total cost was $55 for the alternator, and $8 for the short tow.

Be pro-active!


An alternator isn’t like trying to get the last little bit of shampoo out of the bottle. Why not replace it now? The new one will likely outlast the rest of the car anyway.


First of all, I’d like to say thank very very much for all of your replies. They are all very helpful.

The symptoms: The light on the dashboard, i.e the overall light at night and the icon lights, front/head lights are all dimming and sort of flashing on a regular basis.

The diagnose: I did some research and found out that out local auto parts might be able to check my car alternator and battery, so that’s what I did. One of the store clerk took out a handheld device and hook it up with my car battery. (He said that will test both battery and alternator, I took his word for it) The result was something like the battery is 474 out of the 600 out of the sticker on the battery itself. And the alternator was 12.95 out of 13.5. I have no idea what are the unit of those number, could anyone of you explain? With common sense, I take at as a 70%-80% capacity?

The battery: it’s about 2-3 years old, bought at Costco. Is this about time to change the battery too? How would I know when to change it? Get it check on a regular basis?

The Towing: I did sign up for AAA Road Assistance annual subscription. I learned this lesson the hard way when I caught off guard in an accident and having to pay more than I paid AAA annually for that one time towing.

The Mechanic: I don’t really have a “trusted” mechanic. I normally shop around a couple local mechanic and compare pricing. Could someone here refer a mechanic to me, if you happen to live in Long Beach, CA 90802. I’ll try Car Talk mechanic list. I heard this from the show.

The Repair: I got a quote from a local mechanic for $200 to “change” the alternator. He said the alternator cost $140, which mean $60 in labor, and it’s one year warranty. I check a local Kragen store, they said the alternator is $172 with the old one return to them and it’s limited lifetime warranty.
I want to buy the alternator from the store for the “limited lifetime warranty” and have the mechanic replaced it for me, presuming he agrees to replace it for $60. Does anyone have opinion about this? Or should I just go with $200 from the mechanic quote.

Thank you very much everyone for your suggestion and advice.


From what you describe it sounds like you may need an alternator, but you’ll want the mechanic to thoroughly check out the battery and the connections. And much better now than later. As for buying one for the warranty, check with your mechanic. It’s common for them to make something on parts, too, so he may not want to do it for $60. Ask him for the total cost if he gets the ‘limited lifetime’ warranty.


“I did sign up for AAA Road Assistance annual subscription. I learned this lesson the hard way when I caught off guard in an accident and having to pay more than I paid AAA annually for that one time towing.”

Don’t assume that this coverage will necessarily come to your rescue when it is needed.

A few days ago, someone posted a situation involving AAA leaving his wife stranded–literally stranded–for many hours after telling her that their local towing affiliate could not come to her help. Apparently there was no attempt on AAA’s part to enlist another towing company from a greater distance. If not for the woman’s husband locating a towing service on his own, she could have been on the side of the highway for a few days.

I have heard other stories of incredibly long waiting times–2 or 3 hours–for a AAA tow. I’m glad that you have towing covererage, but I don’t think you should assume that it will really help you when you need it. Maybe they will come to your rescue promptly, and maybe they won’t.


The last alternator I had repaired had 128K miles on it, was still working but was getting noisey, so I repaired it.