Removing the front rubber engine mounts requires getting under the car and going up inside a hole in the subframe to remove the main bolt. And it can be a bear! I don't know who they hired to tighten these at the factory, but he must have been a brute. These hex bolts are usually in very tight, and you will need a heavy, strong, and tight-fitting 8 mm hex socket. In many cases, only a 1/2 inch drive will do. This is a 3-inch long special socket. You do not want to round out these bolt heads. New bolts can be purchased separately. See below:
Product Details
Super strong and sharp tip. 1/2 inch drive for extra torque.
This tool works on 123 126 DIESEL 240D, 300CD, 300D, 300SD, 300SDL, 300TD, and 126 gas V8 380SE, 380SEC, 380SEL, 420SEL, 500SEC, 500SEL, 560SEC, 560SEL 1977 to 1991.
This is how you access those bolts. Yes that is correct - way up inside that hole... ( note different wrench shown - now selling impact socket for extra strength.
Related Products:
OM616 and OM617 Diesel Engine Motor Mount Bolt Replacement Kit
PLEASE NOTE: DOES NOT FIT 1978-1980 W116 300SD Motor Mount Arms!