2003 X5 3.0i Driveshaft Issue?
 

Hey guys, I live in NC and we just went through some pretty cold weather, but I took my X5 out for a drive after the storm. I was at a light and I hit the gas pedal pretty hard to get ahead of someone and when I did I heard a loud boom. Engine seems fine, transmission shifts, there are no leaks occurring anywhere but car won't go anywhere. I do hear a noise, maybe the transfer case but I'm not sure. Definitely not a mechanic, but I'd appreciate any help.

The driveshaft splines let go most likely - At the minimum you'll need a new longer end on the driveshaft, perhaps an output shaft on the Tcase to mate the driveshaft too - and would be good to do the T-case chain while its out -

Good luck

It is most likely the front driveshaft, but check the half shafts. I don't know if this is true for the ATC motor-activated transfer case, but with an NV125, if just one a half shaft (or driveshaft) spins freely with no resistance, the vehicle goes nowhere. I had a half shaft pop out of the rear dif one time and got the same result: car will not go forward or backward under its own power. Check to make sure all your half shafts are seated all the way. Then see if you can spin the front driveshaft by hand with the rear wheels off the ground. That would be bad. If RB is right, you will see it spinning in the input of the dif, which would indicate your splines are toast.

Other item that can let go is the Guibo.

Update:
 

Got the car on the lift and when I put the car in drive the rear wheels are turning. My dad is a mechanic and is guessing the splines are bad, or a problem in the transfer case. He hasn't really had the time to look at it yet. I'd appreciate any help guys.

You can put a stethoscope on the transfer case by the output and listen for spline skipping noises. You can also wiggle the front drive shaft (with the car off) and see if you have excessive play between the shaft and the output from the transfer case. If the splines are good, you should see the output and drive shaft move in tandem. If the splines are shot, they move independently. You can also apply the parking brake and turn the front wheels and watch to see if the drive shaft spins independently of the output. I just pulled my drive shaft off to find the splines were perfect and have to figure out want else may be causing the grinding I hear once in a blue moon.