Won't start
 

Hey guys having this issue and hope someone can help. So my x5 has been sitting for awhile and the battery died. So I bought a new battery since it was old anyway and hooked it up, tried to start it but the starter wouldn't engage. I hit the key and all I hear is the starter spinning but the motor doesn't spin.

OK so now I need a new starter so I replaced the starter, bought an advanced auto unit for $130. I have used these same starters before in two other BMW's that I have owned and they have worked no issues.

So I replaced the starter myself got the car back together, hooked the battery back up, hit the key and the same thing happened. I can hear the starter spinning but the engine does not turn. WTF

So before I rip the whole thing apart again because maybe I got a bad starter,
Is there ANYTHING that I may have missed in regards to replacing the starter?

It's the same problem I had before, I can hear the stater spinning but it wasn't engaging the motor.

Thanks for your help

So the starter was working properly before you let the car sit and the battery died? I get the feeling there is some information missing here.

Yes The car sat for like 3 months and thats why the battery died.

I never had an issue with the starter previously it had worked fine up until the car sat.

What information do you think is missing?

That maybe there was a problem before or there was work done while it was sitting. There is not a lot of things that can cause a starter to spin and not engage. Are you sure it's the stater you hear spinning? no grinding, clicking or clunking? Is the engine definitely not turning? Can you check the voltage at the starter?

I am positive it is the stater i hear spinning, i marked the cooling fan with a pen to see if it would move when I turned the key and it did not, the engine is not turning. If the starter is spinning when i hit the key i am pretty sure its getting voltage. I don't hear any clunking, clicking or grinding. The only thing that i can think of is that maybe i reversed the polarity of the wires connected to the solenoid. But I could not have done the either because the post are different sizes! I remember bitching about it taking it apart. I have pics Im a post one

Before disassembly
https://photos.app.goo.gl/fXfdSs2d49mHmrjy6

Like an asshole i didnt take a pic of the new starter installed. But as you can see by the picture there isn't much I could have gotten wrong. There is even a pin the starter has to fit into to make sure your alignment is correct.

Check the voltage at the starter when spinning. The starter motor winding itself provides the ground for the solenoid pull-in winding to engage the starter so for the original and the replacement starter to have the exact same problem is highly unlikely. Better chance there is only enough current available to spin the starter motor without pulling in the drive. Maybe a ground issue. Try using jumper cable.

Did you clean those terminals before you put it all back together?
In my auto fixing history I have done a number of starters but not on an m54.
The solenoid has wiring that energizes it to push the starter gear into the gear on the back end of the motor. Flywheel on a stick shift flex plate(?) on an automatic.
When the started motor just spins, the solenoid isn't being engaged. You can try tapping on it to get it unstuck. My suspicion is that you have a small wire issue in the wires that activate the solenoid. I have my motor torn apart about like what's in your photo if you want anything checked, let me know. Or photos...
Can you stand on your head and get multimeter readings to see if you have power to the solenoid or jumper it to see if it goes?

Thank you for this thought, i agree the solenoid is not being activated so maybe it's not getting the input voltage it needs.

What could cause the solenoid NOT to be getting the input voltage?

Try a jumper cable as mentioned above. You can also make some jumpers by buying an alligator clip assortment at Harbor Freight. Maybe get some contact cleaner and get the corrosion off the terminals.