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Just before christmas my car died while my girlfriend was on her way to work. She told me that when the car stopped it went completely silent (no engine/lights/music). Since she drove for about 15km (mostly highway) before that happened I suspected a problem in the realm of generating electricity. Bad smell made me fear for a more expensive defect of the clutch.

Fast forward and the nearest mechanic (to whom the car was towed) called and said the car is running again (with no work done), but the starter is in bad shape and he asks my permission to replace it since it might be related to the problem.

If my usual mechanic asked me that I would say "if you think the car is still worth it, go ahead...". But in this case I don't 100% trust the guy since the whole thing looks a bit shady to me (for example: he said his workshop could be found on the internet, which I couldn't(even looked up a company index of the town) And that's not the only thing)

So my question is:

Is it pausible that a defective starter stopped my car?

My googlefu brought less than satisfying results. Most sources I searched simply pointed to a faulty battery if the starter won't work. Only one site ambiguously suggested that such a defect could cause other issues, but nothing so far detailed what that could really be.

My main fear is that

  1. the mechanic simply didn't find anything and wants to do something so the invested time isn't wasted and
  2. the car simply works again because he charged the battery and I will have a stopped car when I arrive back home (altough a mechanic should notice the battery light if that is the case i guess...)

The car is a Toyota Corolla with 20 years and around 150.000km

I would prefer answers that go beyond yes/no or trust/don't trust that guy. I would say I only have an average understanding of cars, but when an issue arises I love to know as much about it as possible (which occasionally annoys my mechanic...)

Thanks in advance

UPDATE for anyone interested in my experience:

due to COVID/Home office my fetching the car was a little delayed but now I have it back. The original (possibly shady) mechanic did not charge me anything since he didn't do anything except look at it, which of course built a little trust, I gave him some money anyway since it's still his time and the towing alone was very valuable in that situation (the car chose an inconvenient spot to break down)

concerning the starter: as mentioned in the comments I drove the car to my trusted mechanic afterwards and he was surprised the starter did anything for me at all, since it didn't make a sound for him altough the power was present. So that part was true.

As for the breakdown: my mechanic couldn't find the cause for that either so he simply did a bit of "usual suspects" kind of maintenance hoping that might help. It runs a little smoother now and I'll have to see how long it stays that way. But for now all seems good. (and we half expect to retire the car this summer for other reasons anyways...)

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    If the car is running, without any work, thank them and take it away to your "usual mechanic". It is unlikely that a bad starter motor could be responsible for making the car break down while running.
    – Weather Vane
    Jan 5, 2021 at 13:13
  • Are you sure it did not run out of gasoline ? Or, an intermittent fail of the fuel pump ?
    – blacksmith37
    Jan 5, 2021 at 15:45
  • @WeatherVane now it seems obvious, previously I was stuck at thinking "I'll have to pay to have it towed to my mechanic", thanks for pointing out the (now) obvious! :)
    – Livor
    Jan 5, 2021 at 16:43
  • @blacksmith37 running out of gas does not stop the music
    – Livor
    Jan 5, 2021 at 16:43
  • You'll need another car to go pick it up, and if you fear another breakdown on the way back, make sure you have a tow rope with you.
    – Weather Vane
    Jan 5, 2021 at 16:51

2 Answers 2

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Is it pausible that a defective starter stopped my car?

For most modern day vehicles, no.

There are two reasons I state this. First, since the starter started the engine and it was running just fine, I'm going to have to assume it did its job, then retracted as it was supposed to. Even if it hadn't of retracted, the starter has a one way clutch on it, which, in the case of it remaining engaged to the starter ring gear, will allow the starter gear to over run the starter motor. This would not allow the starter to stop the engine if it were to stay engaged.

I agree with @Weather Vane's idea of driving it to your mechanic and have him look it over. It could very well be the starter is bad. However, I'd be looking for a second (read: trusted) opinion on the matter. Also, I don't know the exact situation ... it could very well be the mechanic you'd be picking the car up from might charge a diagnostic fee for just raising the hood. Don't be surprised if they do.

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    Some will make a "storage charge" too, and the original tow will need to be paid for (if not arranged by breakdown insurance).
    – Weather Vane
    Jan 5, 2021 at 17:52
  • I just now drove the car to my mechanic and he will look it over (it was a rough ride for the first few km btw.), for now he thinks the starter might have to be replaced but the cause of the breakdown is likely something else. I will know more next week and will accept an answer afterwards
    – Livor
    Jan 8, 2021 at 16:36
  • I accept this answer since it comes closest to what my mechanic told me
    – Livor
    Jan 27, 2021 at 18:19
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It is possible that the starter did not disengage after starting the car and continued to crank (whether still connected to the flywheel or not). So at that point the engine is charging the battery (and powering everything else, like the lights) at 80A, while your starter is discharging it at the rate of 117A. This is a difference of 37 amperes, which will come straight out of the battery and depending on how well it was charged to start with will take only a few minutes to completely drain it.

Now, if this indeed were what happened, your starter will be in pretty rough shape, in addition to being defective from the beginning.

So the answer is yes.

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  • Are starters fitted with a one way clutch to prevent the engine overspeeding the starter motor? Those clutches are based on an inclined ramp.
    – Solar Mike
    Jan 6, 2021 at 11:04
  • Since starters don't spin as fast as an engine does while running, IF the starter were to stay engaged AND IF the one way clutch didn't do its job forcing the starter to be driven instead of the other way around, then the starter would act as a charging device and actually provide power back to the battery ... that wouldn't last too long, though, because the brushes would soon wear out, then it could do neither and would just be free spinning. Any which way, your answer is incorrect.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jan 6, 2021 at 14:09
  • @Pᴀᴜʟsᴛᴇʀ2: I appreciate your insight into the correctness of my answer, however I did say "whether connected or not" - meaning the overspeeding protection may or may not have disengaged the starter gear, however if it is still powered - it will consume significant power and not act as a charging device.
    – EᑎOT
    Jan 6, 2021 at 15:05
  • When the starter runs, it's the drag on the starter which causes the amperage draw. If the starter was somehow still connected to the engine (with starter gear and ring gear), there would be no load on the starter, therefore the amperage draw would be very little in comparison to when it is starting the engine. Your answer implies a misconception on your part. It's not going to consume significant power. It is also the nature of DC motors to act as a generator if they are driven. If it is connected to the engine and running faster than it's supposed to, it will produce energy.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jan 6, 2021 at 15:31

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