Strange non-start/start issue/non-issue
 

On Thursday I went to take my 911sc out (it's a daily driver) but when I turned the key, the engine wouldn't turn over. Each time I turned the key to engage the starter motor, all I would hear was a fairly loud hum.

Had to get to work, so left it for the weekend. This morning I went downstairs expecting to have to pull the starter, bench test it etc etc. Before doing that I have it one more test, and...it started right up.

Although of course I'm pleased that it's now 'fixed', ...What gives? And what should I be doing next? Pull the starter and have it tested?

Thanks
Al

Dead spot in the starter or a failing starter solenoid would be my guess.

Something else you might want to check are the connections at the battery and at the starter. Make sure they are tight. It's weird, I have seen the same loose terminal start the engine and then the next time no dice.

The loud hum you describe may be the spinning of the starter motor without the engagement of the pinion gear into the flywheel. If so, that's a fault in the solenoid. Time to pull the starter and solenoid for a complete inspection, IMO.