About 1 in 5 starts, my engine makes the noise I have recorded in the attachment.

Anyone had this issue before or can point me to the cause?

 

Could it be that your starter pinion is catching on the flywheel teeth when disengaging?

Original 11 year old starter? Could be time for a new one.

/notamechanic

 

Easy answer!
That is the starter over run clutch squeaking.
When the engine first starts to run on its own, there is moment when the starter pinion is still connected to the flywheel.
The "over run" clutch allows the starter pinion to spin faster than the starter while the pinion is pull back/off the flywheel.
Over time, the grease in the over run clutch dies up and that results in this sound.

Answers to question you haven't asked:
• No, it doesn't damage anything. My G37 did this for two years before I fixed it.

• There are two ways to fix this:
(1) Replace the starter
(2) Remove the starter, stand it up with the pinion pointing up and put 4-5 drops of oil between the gear and the shaft, and spin the gear a few times.
Let it sit for 30 minutes and then re-install the starter.

After my car making that sound for 2 years, I oiled the pinion when I took the transmission out to replace the clutch slave cylinder.
That was 6 months ago, and all is still quiet.

So.... spend $$$ or ¢

 

By the way, everyone who replied to this thread drives a white G37 Sport Sedan. What are the odds of that!

 

Thank you both for your responses! Especially SonicVQ for such a detailed answer!