Starter or battery? -- Why wouldn't my car start?

Question

I have a 2007 Pontiac G6 (3.5L V6).

Problem:

All was working fine until a few weeks ago. I went to go start it one morning (warm April day in NC, USA) using my remote start (as I normally do while walking towards it) and it sort of slowly almost turned over but then failed to do so while getting "stuck" in this slow pseudo turning over sound. I stuck the key in and turned the car off since it sounded pretty abnormal.When I tried to restart it, all I got was a click. And from then on every time I turned the key, all I got was a single click.

Battery seems "OK":

I jumped the battery for ~20 minutes (while revving the charging car). No change -- I still only got a click. I then tested the battery with a voltmeter: ~11 V resting, which would shoot down to ~7-8 V when I tried starting the car (i.e., when I turned the key). I took the battery to Autozone and they said it was ok and had 45% charge to it -- they claimed that having that much charge was perfectly fine and that it should not be the problem.

Starter:

So I bought a new AC Delco compatible starter and put it in the car. HOWEVER, nothing changed. The car still simply clicked once every time I turned the key.

Jumping attempt #2:

For the heck of it, I tried jumping my car again.

• (I had tried starting the car at least a dozen times since the problem started, so I thought perhaps the battery had been de-juiced).

Well guess what? Jumping the battery (for 30 min) worked this time!

• After ~15-20 minutes of jumping the cars (while revving) I tried starting the car again and I got a handful of clicks and what sounded like a poor attempt for the motor to start. So I went back and revved the starter-car engine for another 10 minutes. Finally the car started!!

So here's the question:

Was the problem really my starter the whole time, or was it actually my battery???

Think you know? Well there's one more twist:

• For sh*ts and giggles, I took the old starter to Autozone and had them test it. Their machine said the starter worked!!

  • FYI: the machine drove a current through the starter and made the drive pinion spin.

Huh???

Current Status:

The car has been starting/running completely normally for almost a month since this issue was "fixed."

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In Conclusion:

1. Was my starter actually the problem or was the battery just being wonky???

2. Does a testing machine like Autozone's really test the part?

   • Does a tester machine simply test to see if the circuit closes or does it actually test the starter under load?? (I.e., is the test even telling of the actual status of the starter in the car?).

     • I asked the employee at Autozone and he didn't have a clue.

3. Is there something in all of this I'm missing???

   • One person suggested the engine might have "locked up" and the starter might not have been strong enough to overcome this. He suggested for me to yank on the belt to "unlock the motor".

     • Is this bogus or potentially plausible?

     • I didn't get around to trying this method myself. But even if it were true, how would this help me determine whether the starter or battery was truly the issue??

Answer 1

What often happens in cases like these is that, although the starter and battery may be perfectly fine, the battery cannot get enough current to the starter. This is easily caused by:

• corroded battery terminals
• corroded engine ground
• corroded connections to the starter

Your difficulty jumping the battery suggests a poor electrical connection (battery terminals or engine ground), maybe all your finangling with removing the battery (to get it tested) and removing the starter (to have it tested and then replaced) resulted in a better electrical connection being made after re-installation.