I could use some advice on how to get the lower motor mount replaced on my 2006 MC LTZ with 3.9L V6. I ran into a snag when I couldn't get the motor to separate enough from the subframe to get at the upper bolts. Here is what I did.

Put the vehicle front tires up on ramps so I could get under the vehicle. (I didn't remove the passenger tire as some guides say).
Note: the wheel well panel is removed on the passenger side on this car so I can get at the lower part of the motor
Removed the long bolts from the upper motor mounts (aka dogbones). Engine rocked freely from above.
Removed the 2 lower 15mm nuts on the bottom studs of the lower motor mount.
Removed the horizontal 15mm bolt from the bracket just above the motor mount (as shown in some videos).
Using a jack and some soft wood, gently lifted the motor using the bracket by the oil pan.
Problem: As I jacked the motor, the entire front end of the car lifted. I expected the motor to lift and the subframe to stay put creating the separation I needed to get at the upper bolts on the motor mount. What am I missing here? Is it the ramps? If I need to use jack stands, where do I need to position them in order to safely lift just the motor? Or, would it be easier just to unbolt the passenger side subframe crossbar and drop it down while supporting the motor with the jack?
Obviously, I don't want to damage the car or injure myself while doing this. I'm sure I'm missing something here. Anyone have some sage advice?

 

Did you happen to unbolt the transmission side mount as well? If not, the engine would still be indirectly bolted to the subframe via the trans.

 

I loosened both the bottom bolts on the transmission mount about a 1/4" as well just to see if the motor would lift off. Jacking the motor about 2" lifted the car without taking up any of the open space on these bolts either. The motor went straight up and the subframe (and the whole car) came up with it. Very unexpected. I think I need to try jackstands.

 

Finally got this done today. The ramps were part of the issue. Using jack stands on the subframe seem to prevent the car from liftiing up with the motor. I also had to put a ratchet strap on the top of the motor to rock it forward so the alternator wouldn't hit the bulkhead. Once I got the motor up, I had enough room to undo the two extra bracket bolts that weren't shown on any of the videos online. These bracket bolts went upwards into the motor and were 15mm like all the others. Once I got these loose I was able to pull the bracket and mount out over the AC lines that run right beside the mount. I removed the top nuts (also 15mm) from the motor mount to remove the bracket. Then I cleaned up the the bracket and installed it on the new motor mount. The new mount and bracket went back in over the AC lines and dropped into the hole in the frame. It was a bit of a hassle getting the motor to lower back into alignment. Had to work the motor up and down a few times with the jack and loosen the ratchet strap to get the motor to align with the bracket holes. As another poster mentioned, this was not an easy repair. It didn't take any special tools, just a lot of patience and a little strength to push the motor around. It was also nasty since I have an oil leak right above this area so that's my next repair.

 

Happy to hear you got that mount changed! Thanks for the follow up and information on what you had to do to finish the job.

 

Today I decided to change out the transmission mount and driver side upper mount (torque strut mount). This was much easier than the passenger side motor mount since it's easily accessible from the drivers side wheel well. Total swap took about an hour for both.

Here is what it took:
1. Jacked the vehicle up on stands(left and right subframe). Tip: Loosen the driver side front wheel lugs before jacking.
2. Disconnected the large center bolt in both upper motor mounts (aka torque strut mount or "dogbones"). This allows the motor to rock back and forth and it allows you to lift the motor off the frame below using a jack.
3. Replaced the 2 piece driver side "dogbone". There are two 15mm bolts on the radiator frame plus one 13mm bolt. There is a long 15mm bolt and nut on the engine mount side. I left the center bolts out of both of the uppers while I did the transmission mount. Tip: Make sure you leave the two pieces overlapping where the bolt goes. Don't lift up or drop down the arms as you may not be able to get them back in place after you move the motor around.
4. Removed the driver side front wheel.
5. Removed the two plastic retainers for the wheel well cover. This plastic cover hides the transmission mount which is in front of the axle in this wheel well. The cover has a third retainer that was unreachable so I just let it hang and worked around it.
6. Removed the two 15mm nuts on the bottom of the transmission mount.
7. Removed the two 15mm nuts on the top of the mount.
8. Using my jack and some soft wood under the oil pan bracket, I slowly lifted the motor and trans. I had to disconnect a wiring harness on the intake above as it was too short to allow the motor to come up. Raise the motor only as far as needed (about 1.5").
9. With the motor up, I was able to lift out the old trans mount and drop the new one in the bolt holes.
10. Lower the motor slowly. I used a 2x4 from above against the transmission housing to wedge the motor backwards a little as it dropped. Once the top bolt holes lined up, the motor (really the trans) dropped right back down on the mount. Lower the jack all the way and remove it. The motor will rest on the mount.

11. Replaced the 4 15mm nuts on the mount (two top, two bottom).
12. Replaced the plastic retainers on the wheel well cover.
13. Replaced the center bolts on the upper mounts (15mm on both the nut and bolt head).
14. Reconnected the intake wiring harness I had removed earlier.
15. Reinstalled the driver side front wheel.
16. Lowered the vehicle off the jack stands.
<Repair complete>

I should have replaced all these mounts around 200K. You can't really inspect the lower ones easily and they can look ok but still get wobbly when they warm up. I thought my transmission was failing but after replacing all four mounts, my transmission is in better shape than I thought. FYI, one simple thing I learned doing this was to open the hood and have someone else shift from park to reverse to drive with the motor idling. If your motor shifts (ie drops and turns) more than a half inch or so, your mounts are probably failing. Mine was moving a few inches every time it shifted. Just imagine what is happening under your hood at 3000rpm when it shifts from 3rd to 4th. Klunk!. So glad I changed these out.

 

Thanks for the write up, I'm about to replace the bottom motor mount on my 07 Monte Carlo.

ONE THING:
***TO KEEP THE MOUNT FROM GOING OUT EARLY, I'VE SPRAY PAINTED THE MOUNT BLACK & COVERED THE TOP OF THE MOUNT WITH A THICKER CLEAR PLASTIC BAG JUST FROM A LEFT OVER BAG FROM A PRODUCT I PURCHASED WAS SHIPPED IN. JUST USED A PEN TO POKE HOLES FOR THE STUDS AND USED BOX TAPE TO ATTACH THE DOUBLE WALLED BAG AROUND THE MOUNT AROUND THE BOTTOM***

These mounts are made of most likely EDPM rubber which is susceptible to swelling and softening and failing if any engine oil drips on it.
Our engines drip oil so I'd say these mounts MUST be plastic wrapped.

SO I SAY PLAY IT SAFE, WRAP IT FIRST BEFORE YOU INSERT IT!