This is the normal jacking point for your car. Actually the jack holes that Mercedes installs. But whether you do the frame or the jack holes, you will produce the same affect on the subframe bushings. If they are "seperating" while jacking then I would believe the subframe bushings need replacing. It is a rather stout rubber unit that is designed to take the loads your puting on it. If it is separating then it is worn out. The front rubber on the car gets mushy and soft as it ages, then it usually collapses as it compresses, this is caused by the heat and fluids that get on it in the engine compartment. I have seen the subframe mounts just drying out and cracking.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car