Our truck 2005 Ford Expedition makes a grinding noise when we turn the ignition key. we changed the starter but it still makes the noise of "when you turn the vehicle on again and its already running". You know that noise right, well that's what it sounds like. What do we need to fix?

broken tooth on the gear need a new starter

Dodges have a gear reduction in the starter, usually. It could be wearing out. Have it checked out at a rebuild shop.

Have an auto electrician look at the problem but I suspect that the starter solenoid is starting the armature spinning before the pinion gear is properly engaged in the flywheel teeth. If so the starter can be repaired either by a new solenoid or adjusting the pinion movement before the armature gets power.

If its a grinding noise, it could be the starter or the flywheel gear.

Possible defective starter but most likely Flywheel.

Dead Battery
Loose Cables
Bad Starter Solenoid

it may be the drive shaft or the rear axle or a wheel bearing

lest someone help you tapping the starter motor while you turning the ignition key
if that helps it means your starter is bad and it needs a new one

Apparently the vehicle was in park enough to get the key out, but not enough to get it to turn to start or allow the remote starter to work. Once it had been jiggled around and put ALL the way into the PARK position, all works well again!

do you mean engine rolled over or cranked over and would not start?or is it that the starter would just click? or did starter sound like it was wineing and you had to keep on and off the key until it findley started? if any of your answers to thies questions is yes (except first question) its time for a new starter. as far as the grinding noise don't worry about it, that's what makes me believe its the starter. install new starter, problem solved.