E36 M52B28 Engine not turning while starter spinning.

[LemonHunter 583]

Well after cleaning out my lifters and getting everything back together, I pulled the plugs and the fuel pump relay. 

Turned the key and could hear the starter spinning, but the motor wasn't engaged to it. 

Prior to this it has never had a problem starting during my ownership. 

The two things I could attribute to are me having rotated the motor via the crank a few times will getting everything off and on,and it spent a week with its front on jack stands. 

Any thoughts and/or fixes? 

[Eagle 1680]

Id check battery voltage and connections first. Otherwise it maybe something stuck or bad internally, jacking it up may of disrupted something. Try giving it a few taps with the ignition on or undo it from the block and see it if gear is actually extending with the key on

[LemonHunter 583]

12.7V batt, and I'm an idiot. 

Just realised I hadn't actually turned one of these over without plugs. 

Just silently shoving air out the plugs.