Here is my experience replacing the tranny and engine mounts on 06 E320 CDI-OM 648. Both engine mounts once unbolted from the brackets are removed rearward, not sideways or forward. Using a flex head combo wrench, non-stubby, allows access to the top bolt on the right side, I found the wrench long enough.
I used OEM Mercedes parts: R-2112403017, L-2112400417, T-2122403018
About RAMPS: DO NOT TRUST the 12,000 pound Rhino/Gorilla plastic ramps from Home Depot, I bought these from there, drove another car up on them, went for parts and returned to find one of the ramps had collapsed. It was 90 degrees out on concrete. So I made wooden ramps from 2 x 10s with board lengths 38",34",30",26",22",18", screwed together with 3" screws, (6) torx head screws per board, bevel one end to 45 degrees to make driving up a breeze, the top board has a 3"x 3" chock screwed down with two 6" screws. You can easily negotiate driving up them by yourself if you count the steps to know when you are on the top board. (Note: your better off judging when your at the top without good help because a wifey or drunk friend won't put their hand up in time anyway.) I also put a steel fold down handle ($3.50) on the sides 5" from the back and centered. It makes handling them easier. AND ONCE YOUR UP THE RAMP CHOCK THE REAR WHEEL.
Tools: floor jack, ramps for at least 8" height, creeper (the $20 plastic one from Harbor Freight is pretty crappy and drags terribly on level smooth concrete, I weigh 180. So I am going to invest in a better one, soon), (2) 18" inch locking extensions (Harbor Freight), 3" 3/8" extension, 3/8" drive impact type swivel, 3/8" breaker bar ratchet, 5/8" or 16mm flex head combo wrench (Gearwrench 9710), 3/8" drive sockets: 16mm socket, 13mm socket, 12mm socket, E12 socket. 7mil Nitrile gloves (Harbor Freight), leather gloves, rubber wheel chock (Harbor Freight)
Step MOD 3 and 4: The following 3 and 4 steps are TOTALLY UNNECESSARY in the writeup:
3. Open the hood and remove the top engine covers.
4. Remove the right (passenger side) front wheel. You will need as much space as possible to work there. Removing the left front wheel is optional. I don’t think it makes a difference.
5. Unbolt the two mount bolts from the undercarriage – PITA 2. Wrench size 13 mm, they are easily removed with socket and extension.
Step MOD 5a: remove the TWO bottom bolts (13mm) on the trans mount BEFORE JACKING the engine at the bell housing, if you jack before removing the TWO trans bolts you will put stress on the trans cross member and tranny!
Step MOD 6: IF YOU JACK ON THE OIL PAN remember it costs $500!! not including labor!!!
Instead I jacked on the trans bell housing, its beefier, but
DO NOT JACK THE ENGINE UP UNTIL STEP 7c so skip step 6!
6. Lift the engine with your floor jack. Initially you need to lift it no more than 1-1/2 inch. PITA – 5. Good floor jack is necessary in this step. Be careful there! Slide the jack under the front center of the car. Find the imaginable lateral axis below the engine that connects the two engine mounts. That is where the engine is balanced and where you should lift it. The point is about the middle of the oil pan, 2-3 inches ahead of the drain plug. Put 1 or 2 square pieces of wood on the jack to distribute the pressure surface on the oil pan as evenly as possible. Start lifting SLOWLY and CAREFULLY. Thatis where the second guy comes into play. While one is lifting, the second is watching under the car the process. You must not allow any damage or deformation on the oil pan.
Step MOD 7: the bottom trans mount bolts should have already been removed (Step 5a), go ahead and remove the two side bolts (16mm), but you can't remove the trans mount yet BECAUSE you haven't jacked up the engine YET!!
7. Time to remove the rear transmission mount from under the car. PITA – 3. Two bolts 16mm wrench connect the mount to the transmission. Two bolts 13 mm wrench connect it to the chassis. All of them are easily removed. Slide out the rear transmission mount and install the new one.
Step 7a mod:
On the right side engine mount bracket, the bottom rear bracket bolt secures a cable harness loom, removing the bolt (E12) frees the loom and allows an extra inch of clearance when removing the engine mount.
Step 7b: On the exhaust pipe there is a hanger just past the coupler, this is to the rear of the CAT. There are two studs on the hanger clip, remove the two nuts and the clip. This allows the exhaust pipe to move upward with the engine when jacking it up.
Step 7c: NOW YOU CAN JACK THE ENGINE. Remember as you begin to jack up the engine, you are taking a load off the springs so the whole car will be moving upward at first, continue jacking it up slowly until you see about a 5/8" clearance between the bottom of the engine mount and subframe. You don't need an 1-1/2" clearance as stated in the writeup.
Step MOD 8: remove the right side top bolt with the 16mm or 5/8" flex head wrench from underneath, access will be forward of the mount. Metric fasteners on your machine but you can use a 5/8" flex wrench in lieu of the 16mm. THERE IS NO SLOP, so a 5/8" fits perfectly. 16mm = .063", 5/8" = .0625". Make sure the wrench is fully seated because you can't see it and you are going to be applying a lot of force to crack the bolt loose, you do not want to butter up the bolt head!! Wear a leather glove on your wrench hand, it will allow you to apply a greater force.
Step MOD 8a: remove the left side top bolt from the topside of the car with the long extensions and impact swivel, down along side of the top engine cover you didn't need to remove.
Both mounts are removed rearward/aft.
When installing the new mounts, put in the top bolts first making sure the pin is aligned into the groove. Just finger tighten top bolts to allow alignment of bottom bolts.
With the trans mount side bolts installed, lower vehicle until the bottom of the engine mounts have about 1/4" of clearance between the bottom of the mount and the subframe.
Finger tighten bottom bolts on ALL mounts, tranny mount included.
Lower the engine, tighten top bolts first, make sure the mount pin is still engaged in the groove, then tighten ALL bottom bolts (4 total).
Torque everything, 25Nm on the bracket bolt (E12), bottom bolts (13mm) 30Nm, top bolts 45Nm.
Replace bracket bolt (E12) and loom, and exhaust pipe hanger clip and the 2 nuts.
Install the bottom panels.
YOU ARE FINISHED!!! This job is not difficult if you follow the steps in order!!
WAIT, Close the hood and start your engine and put the car in REVERSE to pull off the ramps!!! AFTER YOU HAVE REMOVED THE REAR WHEEL CHOCK