5.7 suburban
New battery
Worked perfectly fine till a few months ago. Seemed battery was going out. If lights were left on more than 10 minutes would needed to ve Jumped.
So i was just careful. Then one day wouldn't start. And stopped cranking normally.
I couldn't jump it. It sat few weeks then I was able to jump it again.
Intermittently this always happens now. Got a new battery and its still doing it.

It cranks when I turn the key for a few good seconds of crank. Then it stops cranking and then sounds like only my starter is spinning.
I got my starter tested at orilleys and they said it was fine. I found a bench test on YouTube and it seemes to preform properly according to it.
Can it just not work properly under load?
My security light isn't staying on.
I tested down at my starter both from battery and the small "s" termInal. Both have good power.
Then I tried putting on a remote starter switch and it does the same thing. Still only cranks shortly then I only hear the starter spinning.
Watched another video about load test. Positive I think it was .17 neg .24
My ground by the battery is clean. Did clean other ground passenger side under block.
All my fuses and relays seem fine.
Fuel at the rail.
It just weird cause everyone in a while before I got ths new battery today it would work intermittently a day here and there.
Is it just the starter?
What am I missing?

 

Welcome to the forum.

Maybe the bendix on the starter is shot or a tooth is missing on the flex plate.