2007 Jeep Grand Cherokee with 5.7L Hemi.

Hold your jaw for this first part of the story.
Jiffylube let me leave without a drop of oil. i stopped within minutes of leaving the place knowing something had gone very wrong. I was too late. engine fried.
I had babied that motor from 36k-97k.

Jiffylubes insurance paid for everything and a replacement motor with 98k was put in by a jeep dealership.

it runs perfect like it never happened, however it starts with a very slow hard crank then fires on the 3-4 crank. once running its fine. it always starts but everytime you feel like its not going to.

I checked the battery with a meter. holding at 12.4, drops to 10 on start comes back up 15 once running with lights on. I put a new AGM higher end battery in only a couple months before this all happened.

Have a call into the dealership to hear what the tech has to say but im sure he knows. he test drove it. they worked on it for a month changing engines!

any thoughts? could it be a motor issue?

before all this it started quick and strong.

 

i just realized it could be a faulty starter that came attached to the new replacement engine? thats got to be it.

my old was fine but they didn't swap them. he just got the replacement and stuck it in with whatever was attached.

 

At 12.4 volts the battery is 40% discharged. Have the battery load tested, I bet it tests bad. It should not drop to 10 volts while cranking, it should be around 11volts while cranking with a gear reduction starter.