I did it just the way you described: lying on my back on the garage floor. It was not so bad. I raised the car onto jackstands at the front, so I had plenty of room. The engine is attached to each mount with only one bolt. Each mount is attached to the frame by 2 other bolts.

You will need 2 supersockets; 8mm and 7mm in my case, and a selection of extensions of different lengths for your ratchet. On my car, the passenger side mount was a breeze. Removing the old mount and installing the new one took only about 15 minutes.

Driver's side was easy with the exception of the bolt on the engine side that held the mount to the frame. That one was inaccessible from above and I did not have room to get a ratchet on it. I had to use an allen wrench to remove it and even then I could only move it one flat at a time. Since I could not see the head of the bolt, I spent most of the time trying to get the allen wrench into the hole. That part of the job was very slow and frustrating work, but not technical. You just need the patience to slog through the process. Overall it probably took me 2.5 hrs. to do the 2 front mounts, spread out over 2 evenings.

Perhaps one of the more experienced forum members can offer a tip on getting that bolt out more efficiently?

Thinking about the tools required, you also need a torque wrench to tighten the engine-to-mount bolts and a floor jack to lift the engine a little ways off the mounts so you can swap in new ones.

Since the factory manual says that the job should be done with the weight on the front wheels, I tightened engine-to-mount bolts only part way with the car in the air. I slid back under the car and torqued them to the final value once the car was back on its wheels and the jack was out from under the engine. That was a tight squeeze. If I had been a bit brighter, I probably could have blocked up under the front wheels while they were in the air and given myself some more room.

I also bought the rear mount. I noted that it required the removal of a frame cross-member near the back of the transmission. Since the forward driveshaft flex disk is right beside the mount and mine needs to be replaced, I will do those jobs at one time. Fortunately my rear mount appears to be in relatively good shape. I also plan to install a new engine shock on the passenger side. I could extend and compress mine by hand easily. It was obviously not doing much damping of engine motion.

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1985 300SD, 203,000 miles, dark blue

Lil Sarah says: "Poor old Grandma Blue Car...She's sad."