Onan Microquiet 4000 making grinding noise, won't start.

Thanks everyone, I appreciate the feedback. Kpack- The full model number is 4KYFA26100J. We have had highs of the low 20's and lows in the single digits.

I had that going on couple years ago. Starter had enough battery juice to "throw" starter thing to engage, but not enough to keep it engaged. And made treble noise as plastic starter teeth raked across gears coming back into its resting spot. But I didn't know that at the time.

After ton a of reading and thinking I was in big trouble,

I started with fully charged battery after cleaning up battery posts and connections and that solved my problem.

But you might have other stuff going on. Start with easy fixes first.

Could be the starter gear it is plastic. I had the grinding noise and mine had to be replaced

Valves probably need setting. If there not set right or if oil is to heavy or even a vapor lock can make it hard to turn over and gear teeth start slipping and making a chattering sound.
What is your full model number with the speck letter and I'll post the operator and service manual and we'll look at that code 4.
How cold is it wher your at. You also need mm to check battery volts.