W201 Starter not engaging with tested good starter!
 

I thought the starter went out on my 87 2.3-16,
when you turn the car over it just spins and does not engage the flywheel, i got a new replacement one and it does the same thing. no grinding noises or click of the solenoid, just electrical whine from the starter motor. it draws 110A like it would normally to start.

the old one was tested at kragen and was deemed good. the gears pop out to engage and the motor spins. When switched back it's the same story. new one and old one are good. when they are in the car it behaves as if the bendix is out, though the starters are tested fine. only two wires to starter so it's not possible to screw that up, plus they are different sizes.

what circuit during crank controls the engagement?
any tips on what i should check?

http://i14.photobucket.com/albums/a3...ingcircuit.png

this is a starting circuit diagram from a 1989 190e

did some more research, do our M/T's have Neutral Safety Switches? looking at this diagram it seems we do not. or even clutch switches. i know the FPR is good, i can hear the pump and when we push start the car it runs fine. also jumping the starter starts the car. maybe a ground strap is bad somewhere? it's driving me nuts!