One of the bolt holding the driver’s side engine mount is directly under the bracket holding the shock absorber. Only access was from the bottom. Have to use a rigged up tool to work on it.

Option 1:

Metric Hex Insert Bit 1/4" Hex Shank, 6MM Hex Size, 1" Length - McMaster Carr part number: 7389A26

¼” Ratcheting box wrench - McMaster Carr part number:5163A11

Option 2:

Cut-off a portion of the long end of a 6MM L hex key, 1.25 inch long and a 6MM ratcheting box wrench. For some reason, a 6MM replaceable bit is no longer available.

Hex key – McMaster Carr part number: 5984A47

Tool to cut the Key – Dremel EZ Lock: EZ406-02

6MM Ratcheting box wrench - McMaster Carr part number: 5163A22

Due to the blind installation, almost destroyed the threads of the nutplate and the bolt. Used an 8MM x 1.25 tap and die to chase the threads in the nutplate and the threads on the bolt.

Mileage: 292,390

Thank you for the clarification. The 240D was made in January 1981. The manual mentioned the engine stop, but the picture was not clear where it was located. There was a drawing for a self made gauge, but not sure where it is used. Was able to remove the driver’s side engine mount and shock absorber but cannot install the new mounts. Almost destroyed the oil pan trying to lift the engine, but the chassis comes up with the engine. Finally installed the old parts back and took it to a Mercedes mechanic. He was the one who showed me the engine stop located at the back of oil pan. The area was dirty and the part was not readily visible. Lesson learned: clean the area first.

Have to release the engine stop (part number: 123 240 03 65) to raise the engine and insert the new mounts.